Yikes! I have Gaps in My Hardwood Floors

Hardwood Floor Gaps

It’s nearly winter. That means that your hardwood floors are about to show cracks between the boards. If you’ve moved into a new house, these cracks could cause alarm. How could your brand new hardwood floors crack?

Gaps between boards, or cracks, if you will, are not the result of the wood floor failing or falling apart. They are the result of the wood planks shrinking as the relative humidity goes down and the wood floor loses moisture content. The air in the summer has a higher relative humidity than in the summer. This lets the wood flooring absorb moisture and swell. So usually gaps between boards go away in the summer. Then those gaps reappear in the winter as the humidity goes down again. If your builder had installed the floors with too little moisture content at the time of installation, when the relative humidity went up, the boards would have nowhere to swell or expand and they would push against each other causing the planks to cup and possibly rise. Flooring must be installed to allow this seasonal swelling and shrinking.

If you have standard, 2 1/4″ wide flooring, you should not have gaps wider than the thickness of a business card. However, sometimes two or three boards will stick together and move as a unit. This would produce one crack the width of the thickness of three business cards instead of three cracks, each the with the thickness of one business card. This would be considered normal. If you have cracks wider than that, chances are the floor was installed with too high a moisture content.

If your flooring consists of wider planks, your gaps will be proportionately wider. The wood will shrink the same percentage, but the actual dimension of the crack will necessarily be wider. Planks twice as wide will produce gaps that are twice as wide.

Engineered flooring shrinks less than solid wood flooring. This is because engineered floor has a solid wood surface, but the underlying wood is actually plywood. Plywood is dimensionally more stable because it is assembled with the wood grain of each layer running ninety degrees to the layer above and below. Wood shrinks across the grain and not much with the grain. So one layer reisist the shrinkage of the neighboring layer. If you want wide plank floors, take a hard look at engineered flooring. It will remain much more dimensionally stable than solid wood planks, yet the surface, the part you see and walk upon, will be identical to the solid plank.

Filling the gaps is merely a temporary cure. When the wood swells again as the season changes, chances are the filler will be squeezed out. My recommendation is to look around at older houses and observe the gaps in those floors. It’s likely you looked right past those blemishes and maybe even viewed them as part of the “patina of age” and thought they enhanced the charm of the house. Your house will develop it’s own patina and grow more charming every season if you let the nature of wood take its course. Your wood floors are a natural product that abides by the laws of nature. Swelling and contracting with moisture content is the natural behavior of wood.

I always welcome comments. Please feel free to post a comment and share your experience with the rest of us.

I hope this information is helpful to you. You might want to get yourself a copy of my best-seller, Designing Your Perfect House. It is chockfull of valuable tips and advice that will save you many times the cost of the book on your house building or remodeling project. You might also like The Well-Centered Home: Simple Steps to Increase Mindfulness, Self-Awareness, and Happiness Where You Live. It will show you how to make your home a happy place.

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Bill Hirsch | Architect

Bill Hirsch


  1. mannington wood floors on November 25, 2009 at 2:56 pm

    You really can save a ton of money buy installing your wood floors yourself. Most installers in my area charge at least $2 a square foot for installs. It is not that hard and the nail gun can be rented for like $40 per day.

    • Bill Hirsch | Architect Bill on November 25, 2009 at 5:05 pm

      Yes, you can save quite a bit of money if you are handy and have the patience to install the floor correctly. By the way, I was the architect for Mannington Mills executive office building expansion and the company fitness center. I designed those buildings about 25 years ago. They are a first class company.

  2. Jason on December 16, 2009 at 10:38 pm


    Your post was helpful. It is December, and we just had 5″ wide engineered hardwood floor planks installed in our home. We’ve noticed that there are several places in the floor where there is at least a business card gap at the seam where two board ends come together. Do you think this was intentional to account for summer expansion? The reason I ask, is that this spacing is not uniform across the floor. Most of the board ends come together at a tight seam.


    • Bill Hirsch | Architect Bill on December 16, 2009 at 10:54 pm

      Jason – Good question. The gaps in the flooring I was referring to occur along the long edges of the boards. Wood shrinks and expands in a perpendicular direction to the grain. Wood shrinks very little, if at all, in its length (with the grain.) So there should be no noticeable gaps at the ends of the planks. The gaps you have are probably a result of the planks not being installed tightly enough. It sounds like you have a legitimate complaint with your flooring installer.

  3. Sandy on January 6, 2010 at 11:34 pm

    Bill, we had 5″ engineered dark wood floors installed in Oct. Now in cold January, we see gaps along a slight rise or fall near the floor joists. We are very alarmed. The installers supposedly evened out a small dip in the floor from water damage with a tarpaper like material stacked in layers under the wood. The floors have creaked and been noisy since the installation. The floor guys said this was normal and that they would “settle”. We could live with the clicks, but can’t live with seeing the subfloor through the cracks. Our hardwood is a very dark santos red so the cracks really show. Can the floor people correct this?

    • Bill Hirsch | Architect Bill on January 7, 2010 at 10:24 am

      Sandy – There may be several things that might be going on here. I’ll try to cover each. Hopefully one will apply to your situation.

      All wood flooring will shrink and expand with the season. If you live in a very cold climate, the wintertime humidity level will be very low and the wood will shrink a lot. The wider the planks, the wider the gaps will be. Wood shrinks most across the grain and not in the long direction. But engineered flooring should shrink far less than solid wood planks. That’s because the direction of the grain in each ply (layer) of the engineered flooring is oriented in a different direction and the cross grains stabilize each other. If your gaps are very wide, a quarter inch or more, and don’t close up in summer, that is surprising and might indicate a structural problem.

      If you have numerous gaps wider than a quarter, that could be considered excessive. This could have been the result of the flooring being installed when its moisture content or the moisture content of the subfloor was too high. If you can actually see the subfloor, that is totally unacceptable. Are you actually seeing the subfloor or might you be seeing the unfinished tongue in the tongue and groove joint between the boards? Try sticking a business card into the gap and mark how deep it goes. Then compare it to the thickness of the wood flooring to see if it goes to the subfloor. If it does, I’d say your installer owes you a new floor. There is no remedy other than replacement.

      If you are actually only seeing the tongue and groove joint, the gap is no more than the thickness of a quarter, and the gap closes up in the summer then it could be considered to be “normal.” Dark floors show the gaps much more readily than light floors since the light, unfinished wood in the joints contrasts sharply with the dark surface finish.

      You don’t want to fill the gaps with wood filler. This will only be squeezed out in the summer. One suggestion would be to stain the wood within the gaps the color of the finish. You could use an artist’s brush and carefully dab in stain deep in the joint. Tape off both sides of each joint before you do this to keep from getting stain on top of you surface finish. It’s a painstaking process and it won’t cure the gaps, but they wil not be as visible.

      Sometimes the structure of a house will shrink enough to cause seasonal gaps in wood flooring. This usually results in one or two significant gaps located above primary girders or where an addition might have been built on to an existing building. I have a spot in my wood kitchen floor that shows a gap each year. It’s right over a girder. You see this often in older houses. It’s just the house “breathing” with the seasons and reminding you it’s built with wood, an organic material.

      I hope this helps. Good luck and let us know what the resolution ends up being.

      • Rick Malik on September 4, 2017 at 9:18 pm

        To hide the tongue from showing, take a seam sealer bottle (tape the tip and make a pinhole) filled with matching wood stain and run it down the gap. Let it soak in then wipe away the excess. 🙂

        • Bill Hirsch | Architect William Hirsch on September 19, 2017 at 9:36 am

          Rick – That sounds like a clever way to disguise any gaps and not see light colored, unstained wood in the gaps.

  4. Joe on February 3, 2010 at 8:11 pm

    Bill, Your posted reply on Jan 8th was very helpful. I have a New Home that was completed in August 2009 and I now have gaps in my hardwood also. They Run the length of my house everywhere that there is a girder. Some gaps are bigger than a quarters width. I also have some gaps against the grain on the long axis of the planks. The wood is 2 1/2 solid oak (not pre-finished)

    My question is, why do the gaps manifest over the girder and not uniformly throughout the remainder of the floor? Also will the usage of my gas fireplace cause an unusual amount of “drying out” of the planks and cause larger gaps?

    • Bill Hirsch | Architect Bill on February 3, 2010 at 10:35 pm

      Joe – I’m not certain why it happens there, but I have a theory. Every piece of wood in a house shrinks when it loses moisture. Most of the shrinkage occurs perpendicular to the grain. But there is still some shrinkage parallel to the grain (the long dimension) of the wood. The floor joists can shrink a little bit over their length. They usually have a lapping joint over the girders. They are not one continuous board from one side of your house to the other. So I believe what happens is the joists pull apart as they shrink a little. The movement occurs at this lapping joint. Since it is also the location of plywood seams for half of the sheets of plywood in the subfloor, it is more susceptible to movement than other spots.

      More and more we are using engineered floor joists that come in very long lengths. One of the advantages of this is they can actually run from one side of the house to the other. Combining that advantage with the fact that engineered lumber is not as prone to shrinkage ad “dimensional” lumber, and the chance for cracks is greatly reduced.

      I don’t think that using your gas fireplace will further dry the wood and exacerbating the shrinkage. Actually, one of the byproducts of burning gas is water vapor. So it is actually adding a bit of moisture to the air. Dry air problems in winter come from taking cold air that can hold fewer grains of moisture than hot air, and heating it up. Although the air has the same amount of grains of moisture, the relative humidity goes down. The larger the difference between the outside air temperature and the indoor air temperature, the more the relative humidity will drop when it is heated. Your gas fireplace won’t “dry” the air any more than your furnace will.

      Furnaces have to heat the air to a higher temperature than the room actually needs because there is a loss of temperature as the air is sent through the ductwork and delivered to the room. Because of this “over-heating,” the air in the house ends up dryer than it would be if you used a radiant heat system, such as an in-floor radiant system or good old fashioned radiators. The radiant systems only need to heat up the air just enough to make you comfortable. Thus they do not dry the air as much.

      The only cure for dry air in winter is to humidify it. Humidifiers are tough maintenance problems, sometimes. They tend to clog, grow mold if not cleaned regularly, and they can leak. I’ve had the best luck with steam humidifiers. A good humidifier will go a long way toward keeping the moisture content up in your wood and reduce those cracks.

  5. Joe on February 4, 2010 at 6:12 pm

    Bill, Thanks for the reply!

  6. jim on February 11, 2010 at 5:30 pm

    wood under my carpets? There is a large lump under my carpets that honestly feels like a metal rod about 4 feet long, which raises the carpet about 1/2 an inch in a 4 foot straight line. Could this be wood planks under the carpet that have swelled from moisture? Not sure what is under the carpets. You seem to be the expert on wood flooring, could this be possible? Does it sound like something that wood, or plywood might do? Any information would be helpful, thanks!

    • Bill Hirsch | Architect Bill on February 12, 2010 at 10:22 am

      Jim – It sounds like one edge of the plywood sub-flooring or underlayment has warped upward. Plywood is four feet by eight feet in size. If one edge has pulled loose, it could rise like this. Sometimes you can nail it back down by driving finish nails (nails with tiny heads) right through the carpet and into the wood. Because the nails have small heads, they slip right through the carpet and don’t stick up. But this solution is usually only a temporary fix. Finish nails don’t have a lot of holding power and even if they did work to pull the plywood back down, they can pull loose easily and the problem may return.

      The best solution is to have the carpet pulled back, screw the edge of the plywood down and/or grind off the ridge, and re-stretch the carpet. If you don’t fix this soon, you will develop a worn spot on the carpet and even when you fix the issue underneath, the carpet will still show a line. Good luck.

  7. Ken on March 1, 2010 at 6:17 pm


    My house is 3 years old was built using 3 each 2″ x 10″ nailed but not glued girder running left and right with 2″ x 10″ floor joist on ledger strips spanned 15′ 7″ of Southern Pine running front to rear. Our 3 1/4″ white Oak strip flooring seperates over 1/4″ during the months of December thru April and closes completely in May (we can fit 5 dimes in the crack in places). The subfloor was laid and the seam is over the girder and the installers also changed the floor direction with an unglued spline over the same seam over the girder. I believe this created an expansion joint over the girder. The floors were not acclimated before installation and the HVAC unit was not running when installed. Do you have any suggestions on how to correct the seperation problem?

    I believe that the OSB subfloor should have spanned the girder. I am not sure if the seasonal movement is in the floor joist or the subfloor sheeting, I do not think it is the Oak floors but what they are attached to. We do have the normal small cracks throughout our floors. By the way we are located in South West Virginia.

    • Bill Hirsch | Architect Bill on March 2, 2010 at 10:43 am

      Ken – It sounds like you have the “Perfect Storm” of floor cracks. You are correct in thinking that changing the floor direction right on top of the girder and then having a seam between the sheets of subflooring does create a natural expansion joint over the girder. Now all the little cracks gang up in that spot. To compound the problem, it sounds like the flooring was installed when it had the highest moisture content and was the most swollen. When you say that the installers changed directions for the hardwood at that point, do you have flooring that runs parallel to the floor joists? If so, this is a big mistake. that leaves many planks of the wood flooring supported only on the subfloor. Wood flooring should always be installed perpendicular to the framing below so the planks span from joist to joist. The only way to install it parallel to the framing is to install additional blocking between the joists to support the wood planks.

      I doubt that the OSB board it the culprit. It does not expand as much as regular pieces of wood. That’s because it does not have a directional grain. If some strands want to shrink in one direction, opposing strands resist the shrinkage. This is the same principle in plywood. It shrinks a little bit, but not nearly as much as your floor planks will. If the wood flooring planks had straddled the girder, you would have less of a problem. If the installers had not created such an effective expansion joint over the girder, you would have had numerous smaller cracks between several of the other planks. Instead, you see all of the shrinkage of each of the planks manifested in one spot.

      As for a cure, this is a tough one. I talked with my friend, Bill Campbell at Select Forest Products to get some expert advice. Here’s what we came up with. If the flooring is installed parallel to the joists on one side of the girder, I would first recommend installing solid, 2×10 blocking beneath it at 24″ on center to support the floor better. If you have a crawlspace beneath this floor, you might want to have that crawlspace sealed. This will stabilize the humidity and the seasonal floor changes will be less. You need to check the moisture content of the wood floor before doing any repairs. Your builder or a wood flooring installer will have a moisture meter. Check the size of the crack when the flooring is at an 8% moisture content. That’s when you can fill the crack. My guess is that when the crack completely closes now, the moisture content in the floor is more like 10%. So i’m suggesting making hte repair when the floor is at an optimal, mid-range moisture content.

      To do the repair, remove the first piece of flooring running parallel to the crack and replace it with a wider piece of wood. This new piece should be cut with a vertical grain (a quarter sawn or rift sawn piece). That way it can absorb the compression if the flooring expands some more. It should not cup when the floor expands, but it might rise slightly in the middle of the summer if the humidity is really high. Gluing it in place is a great idea, too. In the winter, if the moisture content of the floor drops below 8%, you may still see cracks, but they should be much smaller than what you are experiencing now. One other suggestion is to keep the humidity in the house higher in the winter months. This would mean installing a humidifier. For those, I would recommend a steam type humidifier. They are easier to maintain and seem to work better.

      I hope this helps.

  8. Ken on March 3, 2010 at 4:34 pm


    The strip flooring is installed perpendicular to the floor joist with the flooring running left and right, what I mean is the male part of the strip flooring on the rear of the house points to the rear and the male part for the front flooring is pointing to the front of the house. The two female grooves join over the girder and are joined with a spline that is not glued.

    Do you think it would be better to remove enough strip flooring and sub flooring to span the girder 4′ on each side and then replace the flooring.

    I am on a crawl space and intend to seal it up, I have been advised by a HVAC company a humidifier is not possible on our system, I’m not sure why.


    • Bill Hirsch | Architect Bill on March 4, 2010 at 12:16 pm

      Ken – I see what you’re saying now. Yes, you do have a perfect expansion joint.

      Altering the subfloor so it spans the girder will certainly help. When you replace the portion of wood flooring, try to use vertical grain pieces to reduce the shrinkage. Also, be sure the moisture content in both the wood flooring and subfloor are around 8% when you install them. There is no way to totally eliminate seasonal cracks. But you should be able to greatly reduce the problem you now have.

      Now I’m curious why the HVAC company says you can’t put in a humidifier. I don’t know what sort of system that would be. If you send me the particulars on your system, including the kind of ductwork you have, I’ll do a little checking and see if I can confirm or refute what they are telling you.

  9. engineered oak flooring on March 10, 2010 at 2:39 pm

    Some interesting comments above. I have been involved in the joinery world for over 35 years and my family date back as joiners to 1853. I have noticed a lot of talk about the engineered flooring in the above articlles. We do sell our own engineered flooring. When we started in engineered flooring I was insistent apon it being on a multi laminate ply wood (ie the ply had to be top quality with 10 layers). This gives the stability and the constant width that does not change with the climate conditions. The top layer in our case is 6 mm of solid european Oak. this gives the flooring its lasting qualities. Nowadays to cut cost many companies have cut back to a thinner top layer and a very poor quality ply. In Bills case useing a solid wood floor it is impossible to stop that movement with the different cclimate conditions that he has to live with.

  10. " class="url" rel="ugc external nofollow">darren montano on June 7, 2010 at 11:35 pm

    I need help how do you fix wooden floor underneath carpet. Plus I need to put the carpet back to the original place. It’s a 1983 mobile home. Please help me out with some info.

    • Bill Hirsch | Architect Bill on June 8, 2010 at 8:43 am

      Darren – I don’t know what kind of repairs you need based on your comment. Most wood floor repairs beneath a carpet require the carpet to be removed and then reinstalled after the repairs are done. If the carpet is in good condition, a good carpet installer can remove it carefully and reinstall it just as it was. If the problem with the wood floor is that it squeaks, sometimes you can drive finish nails right through the carpet to tighten the floor. However, I am unfamiliar with mobile home construction and unsure how the flooring is attached to the house frame. The flooring might be attached with screws or glue to a metal frame. In that case, the carpet will have to be removed to make repairs to the wood floor.

    • James Carson on March 31, 2019 at 9:10 pm

      We built a new house last year, builder installed 3/4” x 3.25” red oak flooring. Wood was brought one day and installed the next. It was very humid and had been raining for weeks. Long story short, floors ended up with 5 different sections having to be replaced, approximately 150-175 sq/ft. Due to extreme gaps in excess of 3/16”. The problem we have now is the rest of the floors are showing crowns. I’m not sure what we should ask our builder to do to resolve. We have approximately 1600 sq/ft of total hardwood flooring. Thanks

  11. cory on August 4, 2010 at 11:00 am

    My floor has this gap and bowed upward poblem in a small part of the floor. My gaps are getting larger everyday in about 10×10 square. Do I have a moisture problem under my floor?

    • Bill Hirsch | Architect Bill on August 4, 2010 at 11:21 am

      Cory – It sounds like you do have a moisture problem. Is it possible something is leaking and water is getting under the floor? Can you access the area below the floor to check the moisture content of the subfloor below or to look for visible moisture? It might be possible to repair the floors. But first you need to stop the moisture. I would suggest calling a good flooring installer and have them look at it.

  12. Dallas Hardwood Floors on August 23, 2010 at 10:26 am

    However, because of construction and installation constraints, not all wood flooring are as easy to install as they seem. Some types of wood flooring and wood floors require a little bit more expertise in handling and installation.

  13. TipTopFlooring on August 25, 2010 at 9:39 am

    Hello, thanks for posting this article, the gaps in the hardwood floor always are problematic area. The hardwood is a “living material” and the changes in the humidity and moisture will live an impact on it. Sometimes as a solution for gaps removing can be siding the boards back but also to add some glue to the end of joint, and to leave the space block, in order not to cause other problems.
    Agree, “the swelling and contracting is the natural behavior of wood”, and sometimes the gaps can appear spoiling the general look of the floor, but the gaps can be polished and smoothed out, so, there is no need to replace the whole hardwood floor.
    Best regards

  14. Kyle on October 10, 2010 at 1:04 am

    Hi Bill

    I would appreciate your thoughts regarding the following.

    I am a timber floor installer here in New Zealand.

    I installed a solid wide board timber floor over joists in a house during summer 9 months ago. Not long after the install the owner complained of cracks appearing on some of the boards approx. 1 inch from the edge of the boards. We agreed to uplift and replace those particular boards including the re-sanding, staining of the entire floor.
    The interesting thing I must point out is that when I went under the house to place a couple of nogs between the joists as support for the boards I was placing in there was a large presence of moisture on the dirt. So much so that my trousers were wet when I came back out.
    I have now been emailed saying that the same problem is now happening to other parts of the flooring which is very frustrating.
    I carried out the neccessary moisture checks of the flooring and the joists, framing before installation and was confident that the readings were correct for the environment.
    I would appreciate your comments regarding this as I am in a difficult situation.
    I note that I did not supply the timber flooring. The owner supplied it.

    • Bill Hirsch | Architect Bill on October 14, 2010 at 11:06 am

      Kyle – It sounds like the homeowners have a moisture problem that is not your responsibility. If there is enough moisture in the crawl space that your trousers get wet when kneeling on it, then there is definitely too much moisture. The subfloor and the wood floor itself will absorb that moisture easily and will expand. The top surface of the wood flooring would tend to be drier since it is in the conditioned space of the house. My guess is the bottom of the flooring is expanding as it absorbs moisture and the fibers in the top of the wood are not expanding. The upper surface is getting pulled apart by the expanding bottom surface. I would also guess that the wood flooring looks cupped as this differential expansion is occurring. You should also check the moisture readings for the floor joists and subfloor in the crawlspace and compare those to the moisture reading of the top of the floor. If there is a big difference, that will ocnfirm the problem.

      The moisture must be controlled if you hope to correct the situation. Otherwise the floor will continue to crack.

  15. carol on October 21, 2010 at 9:45 pm

    Hello. I’ve recently had a solid walnut wood flooring installed in my hallway and kitchen during the summer months. The installers brought the wood to the house the day before (to climatize I believe they said) and then proceeded to install it for the next 3 days. It’s a beautiful floor but it also has developed cracks in between the planks, some the size of a dime or so which I guess is normal from what I read here. My irritation is the creaking noise that my floor is starting to make in some areas. One area is in the corner near my sink and stove and the other is right by the cabinet which leads into my dining area. These are places we step on often. Creak, Creak!! Is this normal? Only installed 2 months ago. My friends tell me the creaking is not normal.

    • Bill Hirsch | Architect Bill on October 23, 2010 at 9:38 am

      Carol – One day of acclimatizing the wood was not enough. One day would have allowed it to get to the right temperature, but it is not long enough for it to change moisture content. Did they check the moisture content of the wood flooring and the subflooring with a moisture meter? Probably not. It sounds like your flooring or your subflooring had too high a moisture content when it was laid. The largest cracks in wood flooring will appear in the winter, when the relative humidity is at its lowest inside the house. If you have substantial cracks now (mid Fall), then they will likely get worse in the winter. This can also lead to the creaking you are hearing as the boards are no longer tightly locked together. The creaking could also be caused by improper nailing or the structure under the floor flexing. Your flooring installer owes you a repair or possibly a re-installation of the flooring. Sadly, wood floors get installed with improper moisture content far too often. Good luck with this and I hope your contractor is reputable and fixes his work.

  16. What Direction Should Hardwood Flooring Run? on October 23, 2010 at 10:04 am

    […] you notice the direction hardwood flooring runs when you walk into a house? It can make a big difference in how it looks and how it behaves […]

  17. […] you notice the direction hardwood flooring runs when you walk into a house? It can make a big difference in how it looks and how it behaves […]

  18. carol on November 12, 2010 at 7:44 pm

    In your reply to my last message…I was wondering…what kind of repair should I expect. If some gaps are normal due to the moisture content going lower in winter, then I guess mine would be fine right? There would be some gapping between the wood no matter what in Wisconsin due to our weather conditions?

    What kind of repair should I expect him to do to the areas that are creaking? There is one piece of wood that moves up and down pretty badly but a couple of other areas just have very slight creak noises. I guess I should ask, is some slight creaking noises normal if the floor flexes? Or should this be a major concern. Of course we had a flooring place put it in with them subcontracting out the work to another guy. Now the flooring place says to talk to the subcontractor since he’s the professional installer. The subcontractor is willing to fix the major spot and has been nice but he says a lot of what we are experiencing is normal in the winters out here with our type of hard wood which is solid walnut. No one can give us an answer as to what the warranty on the installation is. What and who should I expect an answer from in case the creaking or loose boards happen to get worse in the future?

    • Bill Hirsch | Architect Bill on November 12, 2010 at 8:58 pm

      Carol –
      Your floors should NOT creak. As wood dries, minor creaks can develop. But they can be fixed.

      A properly installed wood floor should have no gaps in the summertime and the gaps in the winter should not be big enough to stick a dime into. Ideally, none of the gaps would even be that large and would only allow a couple of playing cards to fit in. But often a couple of boards will move as one and a gap may be a bit wider. Walnut should not behave any differently than oak. So don’t let them give you a line about the species of wood being the culprit. And don’t let them blame the Wisconsin weather. Remind them that the creaking and cracks showed up in early fall when the relative humidity was still high. And if you have a humidifier in your house during the winter, you shouldn’t have cracks in the floor even then.

      None of the boards should move noticeably when you step on them. This is an indication that the flooring was not properly nailed down. The creaking could be caused by nails moving slightly in the wood when you step down. Or the noise could be a result of the floor planks moving against the subflooring below. Or it could be because the subflooring itself is moving. Nails have a habit of working their way loose. Nails that were improperly installed in the first place are going to creak a lot. And it sounds like you have a number of those.

      Minor noises can be cured by some additional nailing from above (face nailing), right through the surface of the wood. The nails should driven into the floor joists and then countersunk and the holes filled. They will then become nearly invisible. But nailing can work loose again in a few years. Screwing down the squeaky spots will work better. The screws can be countersunk and filled with a wood plug to disguise them. For the spots where the boards visibly move, you will need to have those boards removed and reinstalled with proper nailing.

      There should have been a red rosin paper or building felt laid down on the subfloor before the wood floor was installed. This acts as a sort of lubricant to prevent the wood floor boards from rubbing against the subfloor. If this was not installed, you should ask them to at least install it in the areas they need to reinstall.

      Regarding whose responsibility this is, it will depend on who your contract was with. If you bought the floor through a retailer and they hired an installer, either an employee or a sub contractor, to installed, then the retailer is responsible. You should not have to chase down their sub contractor. Your agreement was with the retailer, not the sub. They hired the sub, not you. You hired the retailer to supply AND install the floor.

      I hope this helps. Maybe you can send me a couple of photos of the problem. And if they give you a hard time, suggest that they speak with your architect…ME. Sometimes just the threat of an architect stepping in can get things straightened out. They won’t be as inclined to give you the “brush off” answer. Let me know if you get satisfaction from the flooring retailer. If not, we can add their name to this blog post so others can be warned about your experience.

  19. Trent on December 6, 2010 at 1:12 am

    Bill, I am in the process of having my first house built. I am thinking of putting in 350 sqft. of Brazilian Tiger Mahogany(emerald floors) in my kitchen and dining areas. First is this a good type of wood flooring? It is solid 3/4″ thick and 4 3/4″ wide. Also I would like to know things that I should know before they install my floor so I don’t have these problems that I have read on your site. My house is being built in Wisconsin and the floors will probably be done in late feb. or early march. I am assuming that the way I would like my floors laid will put them parallel with my floor joists. Will this be an issue? And last is there a solid wood floor that doesn’t expand and contract with the humidity? Or am I better off going with a laminate floor? Thanks for your advice.

    • Bill Hirsch | Architect Bill on December 6, 2010 at 3:50 pm

      Trent – If you run the floor boards parallel to the floor joists you should install solid blocking between the floor joists at least every 24″ to support the boards that would otherwise only be resting on the subflooring. Most often the flooring would run perpendicular to the floor joists to give it proper support and help reduce squeaks and gaps. Before the flooring is installed, it should be placed inside the house to acclimate to the humidity and temperature. Then the flooring and the subfloor should be tested for proper moisture content before installing.

      Solid wood flooring will move with the humidity more than an engineered floor. But a 4 3/4″ wide plank, if installed with the proper moisture content and temperature, should not shrink excessively. Personally, I would rather have minor gaps in a solid wood floor in the winter than a laminate floor. Wood looks and feels so much better.

  20. Kristin on January 15, 2011 at 5:45 pm

    Is it not recommended then to pull up the solid wood floor to put back down closer together? My wood floor is solid yellow pine and some of the cracks are wider than 1/8″ and in places 1/4″. We thought we acclimated the wood long enough prior to install, but we have a log home and we think that it was impossible to properly remove moisture from the floor when the logs were still moist. My husband is adamant it cannot be done, but my Fein knife can slice under the t&g to cut the nails, but would I be causing more problems with swelling since its dead winter now? The cracks definitely do not go away in the summer though. I also wondered if I can put wood hardener on the floor after install and resand, the cats are doing a number on it. Will that work?

    • Bill Hirsch | Architect Bill on January 15, 2011 at 6:22 pm

      Kristin – If you have gaps as large as you say and they do not close in the summer, the only solution may be to pull up the floors and reinstall them. It’s not possible to know if you’ve acclimated the wood long enough simply by judging the time it spent acclimating. The weather, the initial moisture content of the wood, and the moisture content within the house will affect how quickly wood will dry. What you really need to do is to check the wood with a moisture meter. Ideally, the wood flooring AND the subflooring should be in the 6% to 9% moisture content range when the flooring is installed. If your wood moisture content is within that range now, then the reinstallation can be done now. If it is drier than that and you reinstall it, there is a risk it will swell enough to buckle in the summer. The timing for the reinstalling should be determined by the moisture content.

      Yellow pine is notorious for moving and shrinking as it dries. Old growth, reclaimed heart pine has a tight grain structure and will not shrink so much. That kind of pine makes a nice flooring. But new pine has more space between the tree rings and can shrink a lot. And the wider the planks of wood, the wider the wintertime gaps will be. New pine is also a very soft wood. It will get marked and scratched easily. You can apply a polyurethane finish to make it a bit tougher, but the wood itself is so soft, pet claws will still damage it. I usually recommend using a harder species of wood flooring if my clients have pets.

  21. carol cooney on January 16, 2011 at 11:17 pm

    Bill. The retailer is finally going to send the sales rep out to look at our flooring soon. He is giving us a hard time about the creaking and seperating saying we are the only ones who have had a problem with this. We said too bad, there’s a first time for everything (but I’m sure we’re not the first. My next question is…what would be acceptable at this point. There are creaking areas in numerous spots around our kitchen floor and more wide gaps in different areas. Can you pull a wood floor up and reinstall like you told the last gal Kristen or should we demand a new wood floor? I really don’t think they gave it enough time to climatize. They delivered it one day and installed it the next. I would attach photos but I need to recharge my camera. The retailer won’t come look at it but he’s willing to resend out the floor installer (he’s been out once and repaired two small areas by nailing from above) and the sales rep he got the wood from. I don’t want a bunch of nail repairs done as I think that makes the floor look tacky. I paid big $ for it and want it done right. Would pulling up the existing floor and restalling it cause lots of damage? By the way we got it from Mitchell carpets in Kenosha wisconsin. we thought we were doing right by picking a smaller retailer. He had nice quality flooring. Our carpets came out great, the wood floor not so great.

    • Bill Hirsch | Architect Bill on January 16, 2011 at 11:56 pm

      Carol – Yes, the wood can probably be pulled up and reinstalled if it was not glued down. It’s a bit of careful work, but it can be done. I would ask the installer what the moisture content of the wood was when he installed it. He probably won’t know. Then ask him if he knows what it should have been. It should have been between 6% and 9%. Prefinished wood must have the proper moisture content when it is installed, just like unfinished wood. It’s not hermetically sealed and it will absorb and lose moisture just like any other wood product. Plus it’s only finished on one side. The other fivesides (the two edges, the bottom, and the two ends) are unfinished and unsealed and can easily take on moisture. The wood probably was at the proper moisture content when it was manufactured, but it could have absorbed moisture anywhere along the way to your house. It should have been acclimated for five to seven days and the moisture content checked before installation. So the retailer either does not know what he’s talking about or he’s lying, to put it bluntly.

      Don’t settle for a patched up job. You paid for the proper job and you should get the proper job. If it is as bad as it sounds, the retailer and/or installer owe you a reinstallation. If they ruin the flooring while taking it up and can not reinstall it, that is their problem, not yours. If they balk, it might be time to chat with the local consumer watchdog from the local TV station. Good Luck. Keep us posted on the outcome.

  22. carol cooney on January 16, 2011 at 11:19 pm

    Oh…forgot to mention the retailer told us it didn’t need to be climatized because it was a finished walnut wood. Is this true?

  23. carol cooney on January 27, 2011 at 8:32 pm

    It’s me again. The retailer and the flooring manufacturer’s rep came out to look at our floor finally together. This is the retailer’s first time out since we have contacted him with our complaints in October. The retailer originally sent out the installer to do a few repairs. As I said above, since then we’ve had more creaking, more gapping and another cracked piece of flooring. Both tried to tell us that the gapping was normal for this time of year. That wood will expand and contract. I told them that I find that much gapping unacceptable. Of course they were trying to blame us for not having the right humidity level in our house. We’ve been running a humidifer off and on throughout the winter. When the humidty gets to a certain point (it automatically turns off so it’s not too much) They tried to tell us it should be run constantly however it will run sometimes until the windows form moisture so I know it has humidity in our house.

    They basically didn’t tell us much more except that the flooring manufacturer rep is going to have an independant inspector come out to fill out a report and give us their determination. My husband asked what this meant and noone would give him a clear picture of what it meant. My husband told the retailer that he’s basically getting the feeling that they are not planning on doing anything about this and the retailer shot back that my husband was having an attitude and that they needed time to meet and discuss what was wrong. I found it funny that they couldn’t give us an opinion right up front as to what they thought. After they left I started wondering what exactly the independant was going to be looking for. I wanted to know the process as a customer so I called the retailer back to ask a few more questions and he told me not to push the issue and to wait for the report. He was not going to answer any of my questions so don’t call and ask him any more. It was out of his hands. The independant would be the determinator of the outcome. So I asked what happens if the report comes back that the installer did something wrong? He wouldn’t answer me. I asked what would happen if the report came back that the wood was bad and he refused to tell me. I told him that I had put my trust in him when I purchased this floor (for about $4,000 mind you) that it would be done correctly and with a quality product. He told me he was not going to give me any answers that might hold him accountable for something he didn’t do wrong.

    Therefore, I am now thouroughly confused. Do I trust this independant person the flooring manufacturer hires? Do I have someone come out on my side to be there too? If so, who would I call? What would be their title? Does the Better Business Bureau help out in situations like this? The manufacturer rep did mention that the independant will come out and measure moisture content in the house and do a full report but he didn’t say what the report would include. The problem is we didn’t know the moisture content of the wood when it arrived here so how can they compare this? Plus, they didn’t climatize the wood as you mentioned it should have been. Now the retailer changed his story and said the wood was in his warehouse for 2 weeks where the climate was similar to our house. This was a lie as he called us a day or two after he recieved it after ordering it 2 weeks earlier from the manufacturer. So the wood wasn’t in his warehouse for more than a day or two. No moisture content measurement was taken, the wood sat on our living room floor (IN A BOX) not even spread out only overnight and installed the next day. Do you have any advice for a customer that has been obviously screwed over in this case. I definitely want to protect myself and have things done correctly whether that means a reinstall or getting my money back. Your opinion would be appreciated.

    • Bill Hirsch | Architect Bill on January 28, 2011 at 9:54 am

      Carol – If the independent inspector can give you some credentials that prove he is truly independent, then you will have some assurance that his opinion will be unbiased. But if he only represents manufacturers and installers, his viewpoint might be biased. You may have to threaten to contact the Better Business Bureau, and/or a local consumer advocate like the newspaper or television station, and possibly a lawyer. You could simply tell the flooring guy that you will review the situation with your lawyer so you know what recourse is available if you do not get satisfaction.

      I don’t know what credentials the flooring inspector should have. It’s not a defined professional field. But there may be someone in your area with wood floor experience AND experience as an expert witness who might be deemed an expert and could give you an opinion on the floors. You might also look at http://www.hardwoodcouncil.com to see if they can steer you toward a hardwood consultant.

      Regarding the humidity, if you start to see moisture on the windows and you have double-paned glass, that’s too much moisture. It sounds like you are running your humidifier properly if it turns itself off at that point. The humidistat is doing its job. Any more moisture and you start to have a risk of mold growth. Naturally, you do not want that.

    • Bill Hirsch | Architect Bill on January 28, 2011 at 10:06 am

      Carol – One other thought. The “expert” they or you might find can not force the installer or supplier to actually correct your problem. If they dig their heels in and won’t fix or replace the floor, your only option might be the courts. In many places, a matter like this can go to a small claims court or a Justice of the Peace court for resolution. I had to do that once with a car repair. There was no need for a lawyer and it did not cost a lot. Fortunately I won that case. But even if I had not won, I would not have spent a lot of money on a lawyer only to ultimately lose. I’m no lawyer and not qualified to give legal advice. But I think many lawyers wuld encourage you in this direction, too. You might want to explore those kinds of options. But whatever you do, the installer and supplier need to know you are serious and you know what your rights and options are.

  24. carol cooney on February 1, 2011 at 1:01 am

    thanks Bill. will do. i have a wood flooring friend who is going to try to be here when the inspector comes out. i think i will pursue this in small claims if need be. what do i have to lose? plus, kenosha wisconsin is a small town. word will get around and he’ll lose some business. if they don’t do anything i will email you back so you can post their name here too like you mentioned. I appreciate your help!!

  25. Haylie on February 6, 2011 at 10:11 pm

    Hi Bill, I have a two-year old townhouse and the second floor has finished with hardwood floor. Recently I noticed this one area (about 1′ x 1.5′) on the floor has bowed. The bow is very gradual and smooth, not like those water damaged wood floor that shows up on google. It looks perfectly normal until you walk from a flat area to this area. When you walk through this area, it will squeak. When you jump on this area, it bounces and squeaks more. I looked at 1st floor ceiling (underneath the bowed hardwood floor), didn’t see any water damage.

    Any ideas? Is this related to the winter weather? Thank you for your any suggestion!!

    • Bill Hirsch | Architect Bill on February 7, 2011 at 9:26 pm

      Haylie – This is an unusual problem to have in the wintertime. Usually wood shrinks in the winter and you see cracks. This kind of bulging upward is usually caused by the wood swelling and trying to expand. With no room to expand horizontally, the wood can only go up and form the bulge or bubble like you describe. But because this is happening in winter, it might be caused by the subloor or the floor framing below the wood flooring shrinking and pulling the floor boards together. This should be easily fixed by an experienced wood flooring installer. Hopefully your builder will return to make the repair. If the bulge is not too severe, he might be able to screw down this section without removing any boards and then plug the screw holes so you don’t see the heads of the screws. If the bulge is too big for this remedy to work, he might have to pull a couple of boards and reinstall them with a tiny bit more leeway between them.

  26. Haylie on February 9, 2011 at 3:22 am

    Hi Bill, I appreciate your suggestion. Unfortunately, my builder and hardwood floor subcontractor are out of business (both 20+ year businesses) in this economic downturn. I will take your your suggestions to a hardwood floor store/contractor to see how much it’ll cost to fix.

    Your article is very educating. It is very nice of you to answer people’s questions for such a long time. Thanks again!

  27. carol cooney on February 28, 2011 at 9:50 pm

    I tried to call our retailer back 3 times to no avail. The independant adjuster never called back. I filed a BBB complaint. Checked the other day and it said closed and resolved on their BBB site. Finally got ahold of Jeff at Mitchell Carpets. I asked him what he planned on doing and he told me “What do you think?” I told him I wasn’t sure and he said he cancelled the independant since I made the complaint. It was clear however that he never planned on having the guy come out or do anything about it anyway. The conversation started off ok but he response to everything I said was that I was being hostile even though I wasn’t at that point. I guess that is his game. Tick the customer off by calling them hostile until they get to that point. Then he can claim that he “tried” to help but couldn’t because the person was hostile. I told him I’d see him in small claims court and he hung up on me. If that offer to put his name out there for bad business is still open…it’s Mitchell Carpets in Kenosha Wisconsin. The owner is Jeff Petersen. He refuses to give you the warranty information after the installation and he refuses to stand behind his products/services. I’m not sure but he may be buying closed out product from wholesalers. Maybe that’s why he is able to offer the deals he does? Buyers beware!! Sometimes deals are too good to be true. Thanks for all your help Bill.

  28. Sandy on March 7, 2011 at 1:21 pm

    Hi Bill,

    My home was renovated last year. Our entire home was gutted, and a second floor added as well as expanding our living space with an addition where our carport used to be. The entire home is 4.5″ Preverco Character Walnut flooring. The floors were laid over a month period, in the fall, September 2010.
    In December we began to notice a “gap” in our kitchen area, ironically where our addition begins. We have a 4 ft concrete crawl space that runs under the home, as well as the addition. The gap has expanded to about 1/4″ wide. My contractor is blaming this on humidity alone, and feels that it will “close up” come summer.
    Upon closer inspection of our addition joists, it was noticed that about 1/8″ was notched out of the joists during construction to reach “level”. Also, the gap is over the “wall” in our basement where the addition was attached to the home. Not to mention that this is also where they simply butt jointed the “exisiting” plywood floor to the new addition plywood floor.

    This is a complete nightmare…the gap runs under the island in my kitchen…and I’m afraid that my entire kitchen will need to be “torn apart” to redo the floor.

    If the contractor “adjusts” the floor joists back to the 1/8″ that they had notched out – do you think the problem will remedy itself?

    • Bill Hirsch | Architect Bill on March 12, 2011 at 6:32 pm

      Sandy – It sounds like the builder should have done a better job of tying the new construction to the existing construction. These seams where additions join existing construction are always vulnerable to pulling back in winter. But the gap should be no more than 1/8″ in the worst of the season and it should close in summer. A 1/4″ gap seems excessive. If it’s accessible, have the builder pull the floor joists back as tight as possible and then install additional joists that lap over the seam between new and old joists. This connection should be glued and not simply nailed. The idea is to get the old joists, the new joists, and the connecting joist to act as if they were one continuous joist with no joint. Without seeing your exact situation, it’s hard to tell you how he might go about doing this. But there should be a way.

  29. Chris Pratt on March 9, 2011 at 1:40 pm

    Hello Bill

    I had 900 square feet of engineered Cherry put down over a sub floor with radiant heat. Both Preverco (wood manufacturer) and the installer said this was a good fit with radiant heating systems. About three months after installation I started noticing 1/8′ gaps at the end seams in one specific area about 60 total square feet. Both the installing company and Preverco have no answers for me but just say its not the product. They both just keep making guesses at what it MIGHT be but nobody is giving me any real answers. I had a builder come out and he pointed out that right below the area where the gaps have developed is the heating room where all the radiant tubes come out. This room generate substantial heat and he thinks has dried this area out more then the rest of the house. Shouldn’t the flooring company or manufacturer have pointed this out before intallation? could this even be the problem? What would you do? Thanks for your help.

    • Bill Hirsch | Architect Bill on March 12, 2011 at 6:24 pm

      Chris – The builder your spoke to is almost certainly correct. Excessive heat will cause wood to over-dry. I think that unless the location of the heating room was pointed out to the wood flooring installer, it would be hard to expect them to anticipate the problem.

      But there are solutions. One would be to insulate the ceiling of the heating room to reduce the heat transfer to the floor in that spot. The other part of the solution is to keep your house humidified. Without the proper humidity, the moisture content of the wood will go down too much and it will shrink. Even the tightest flooring installation can not stand “super drying.”

  30. Sandy on March 21, 2011 at 3:38 pm

    Hi Bill,

    Thanks for your reply! My builder has come back to me with his “plan”, and it goes as such:
    “Upon inspection (by himself and a fellow worker), we concluded there is no evidence of any structural issues pertaining to the kitchen floor. The footings and foundation were constructed as stated on the plans provided and show no signs of settlement and/or cracking. We set up the laser level and found the floor to be exactly where it should be to match the existing home(he provided a hand drawn sketch). There is approximately 1/8″ difference at the area under the refrigerator where the 2 floors meet.
    We are proposing to jack up approximately 3 + feet of this area and install 1/8″ support. The biggest difference measured was at the stairwell area which is in the exisiting area. We also gauged the moisture level and found it to be 26.8 to 28.4% range. This is an extremely low reading and can have a negative effect on the hardwood flooring. The normal range (according to the retail store where the flooring was purchased) of moisture should be 45% to 55%. Therefore the moisture level in the homer needs to come drastically up. ”

    So that’s the letter and “plan” he proposed to us. At no time did he bring in an engineer or any rep from the flooring centre where our flooring was purchased.

    I am afraid that his plan to jack up my floor from underneath could create other problems structurally. Are my concerns justified? Should I be looking for a consult with an engineer? Help!!!

  31. Sandy on March 22, 2011 at 11:31 am

    Oh and I forgot to mention that my hygrometer is displaying a moisture reading of 40% +
    We have a humidifier on the outlet of the furnace, so it can only operate when the heat is ON and the furnace therefore is running. I will admit our humidity levels were low at times through the winter months, however not as low as he claims. Also, I can’t imagine running my humidity levels up at 55%, that would certainly be uncomfortable to live in as well as create moisture buildup in my windows. This is just craziness.

    Thanks in advance for your expertise…MUCH appreciated! 🙂

    • Bill Hirsch | Architect Bill on March 23, 2011 at 8:14 pm

      Sandy – It sounds like you need an architect or engineer to look at this, figure out if the new construction was properly tied to the existing construction, suggest a solution, and stand by your side. I agree that you do NOT wants 55% humidity in your house. If you humidify so much as to see moisture on your windows, there will certainly be moisture on your walls and WITHIN your walls. This, of course, will lead to mold issues. And those are much worse than gaps in the floor. Here’s a link to a good article from the Minneapolis Star Tribune that explains indoor and outdoor relative humidity very well. You will see their recommendations.

      It sure does not sound like humidity is your problem. Stand strong and hopefully you’ll get all of this fixed.

  32. Sandy on March 25, 2011 at 10:33 pm

    Thanks Bill! I’ll keep you posted on what he comes back with! I really appreciate all of your help! 🙂

  33. Sandy on March 29, 2011 at 3:30 pm

    Hello Bill!

    I wonder if you have any opinions on whole home humidifiers. With so many on the market I’m wondering which will be ideal. Our humidity is running quite low, hovering about 30%. We really need to bring it up to a healthier level. Our current humidifier is not putting out enough to keep up. We have a Bypass Humidifier, which is downstream of our furnace, and the humidistat control on the supply end to the furnace. Which means our furnace needs to be “running/heating” in order for the humidifier to be running, since the water supply solenoid only opens when the furnace comes ON.
    I’ve researched and I seem to find that the only system that seems to run “independently” from the furnace is the new Steam systems, for instance the Honeywell TrueSteam. Can you share any opinions in this area?
    I know that the humidity level is not the ultimate cause of my flooring issue, but it is definitely a problem that we need to address prior to taking any steps to rectify the situation.
    Any advice or info is so appreciated…more than you know!!! 🙂

    • Bill Hirsch | Architect Bill on April 30, 2011 at 9:56 am

      Sandy – Sorry to be slow in responding. I use steam type humidifiers all the time. They work the best. AprilAire is another good brand. Regarding the control of them and the aspect of running them run independently from the furnace, my concern would be the potential for building up moisture within the ductwork and promoting the growth of mold. But this is beyond my expertise. So I have referred your question to my heating, air conditioning, and indoor air quality consultant for an expert answer. I’ll post it just as soon as he gets back to me.

  34. Jim on March 31, 2011 at 11:01 am


    Our house was bulit in 2005 (new construction) and has hardwood floors throughout. The upstairs hardwood is in great shape. However, on the first floor (we have an unfinished) basement, there are several locations where there are gaps in the hardwood floor that exceed the “three business card” measurement and are almost five or six business card wide gaps. The worst location is in the kitchen, bathroom, front hallway and the entrance into the family room. There are several gaps that can hold a penny and one that holds a quarter (with room to spare).

    The gaps are there summer or winter.

    I have two questions. Why are the gaps so wide in these areas? Two, can anything be done to correct the problem?


    • Bill Hirsch | Architect Bill on April 3, 2011 at 8:10 pm

      Jim – Chances are the wood of either the flooring, the subfloor, or both were not in the preferred range of moisture content. If you live in a dry climate, humidifying the house will help. But if you live where the summers are humid and the gaps are still there during that season, then the only real “fix” is to take up the floor and reinstall it properly. Fillers can be used, but they are a temporary solution and usually work loose in a short time. Sorry I don’t have a better answer than that.

  35. Jim on April 4, 2011 at 10:49 am


    Thanks for the reply and the information; I was afraid of that. We live in Boston, MA and in the winter we humidify the house pretty well (two small children at home) but even in the spring, summer and fall, the cracks remain. One is so large now and exposed to foot traffic that the one board has started to splinter.

    One more question. Does the entire first floor need to be reinstalled or can we just replace the areas where there are the larger than normal gaps? If we “open” the floor and reinstall, does this cause a ripple effect for the rest of the floor and problems could occur later. Or are we better served replacing the entire room where we have the problem cracks?

    Again, thanks.

    • Bill Hirsch | Architect Bill on April 4, 2011 at 3:22 pm

      Jim – A good flooring installer could take out a few pieces in the bad areas and replace them with slightly wider pieces (that may have to be custom milled) and close the gaps that way. I would suggest that as a solution if the gaps are not scattered throughout the house. Good luck. Let us know how this gets resolved.

  36. Nicole on April 17, 2011 at 11:48 am


    We purchased our new townhome in June 2008 in SC. The first floor was built with Enginerred hardwood floors. We have started to notice that the gaps at the end of the planks have been getting bigger and bigger as the years pass. Each plank is 5 inches wide varying in different lengths. The gaps are measuring anywhere from 1/8 to 1/4. It can be a pain trying to keep the dirt out of these gaps. My husband is thinking of covering the floors with polyurethane aswell. Do you think that is a good idea with these type of hardwood floors? Are the gaps normal? Our home was built on a slab as well if that has anything to do with it? This home was our five year plan and are worrying that if we are concerned about the gaps that when new home buyers come in its going to be a concern for them as well.

    What are your thoughts and suggestions?


    • Bill Hirsch | Architect Bill on April 28, 2011 at 5:00 pm

      Nicole – I have never seen wood flooring shrink lengthwise like that, especially engineered wood flooring. My hunch is the engineered flooring was poorly manufactured and the plywood composition of the flooring was not the proper moisture content when the flooring was manufactured. But that’s just a guess. It also sounds like the wood flooring was installed when the humidity was very high and your heated and air conditioned house has allowed it to dry. And if the concrete slab below the flooring was not sealed and there is no moisture barrier between the concrete and the wood, the concrete slab may be acting like a sponge and continuing to draw more moisture out of the wood and shrinking it even more. Now the question is what to do about it. Have you tested the moisture content of the wood? There may be no permanent cure other than replacing the flooring. But before doing that, you might try wood fillers. They will not be perfect, but they may make the gaps less noticable and help prevent particles from settling into the gaps. Once the filler is in place, you may be able to apply a coat of polyurethane and cross your fingers that it all stays together and looks okay.

  37. Kyle on May 16, 2011 at 6:02 pm


    We bought a new towhouse in 2006 and are trying to put it on the market. We have 2 1/4″ hardwood and over the past few years huge gaps have developed at the ends of the boards. It looks like it is the result of a crack in the underlying concrete slab that runs the length of the house. Now we have a gap in almost every strip that averages about an 1/8″ and at some spots almost a 1/4″. Are shims a possible solution or is reinstalling our only good option?

    • Bill Hirsch | Architect Bill on May 25, 2011 at 8:26 am

      Kyle – Shims may be difficult to install since 1/8″ is a pretty small size to cut a piece of wood. Fillers may be a better option. I would suggest seeking the advice of an experienced flooring installer. He/she may have some clever solution for the problem.

  38. Terra on July 26, 2011 at 9:15 pm


    I’m in the process of having my first home built. Pre-finished hardwood floors were just put down and I want to make sure that the gaps are normal before it’s too late to have fixed. I have been reading the previous posts and the expansion in the summer, contraction in the winter makes complete sense to me. I’m just concerned that if I already have cracks in the floor during the summer it’s going to get a lot worse in the winter. I’m very new to this process and don’t want to fuss/worry over every little thing; however, I don’t want to be taken advantage of either. Does this sound normal?



    • Bill Hirsch | Architect Bill on July 26, 2011 at 11:04 pm

      Terra – You should not have gaps in a newly installed floor no matter the season. And you are correct that any gaps that show now will only increase in the winter when the relative humidity goes down and the moisture content of the floor goes down, too. But you may not have actual gaps in your floors. Most prefinished floors have a beveled edge. These can be fairly large or quite small. The small ones are called micro-grooves. The reason these are there is because it is impossible for a prefinished wood flooring manufacturer to make each plank exactly the same thickness. There will always be some manufacturing tolerance. Very high end prefinished floors can use the micro-groove because they mill their flooring slowly and they can maintain better tolerances. Less expensive flooring will have a large groove because the mill the wood faster. The faster the wood is milled, the more variation in thickness there will be from piece to piece. Unfinished floors vary in thickness, too. But because they are sanded after they are installed, these variations are sanded out and the floor ends up smooth.

      Check to see if your floors have an actual gap or if you are simply seeing the tiny groove and the planks are actually tight together. Chances are they are tight together. It would actually be quite difficult to install wood flooring with a gap due to the way the wood is nailed (stapled) in place with nail gun that shoots the fastener in at an angle. The action of nailing the wood down causes the gap to close. But if you do have actual gaps, the floor might have had much too high a moisture content when it was installed and it has already shrunken some. If that is the case, the flooring was improperly installed and should be replaced.

  39. Mark on January 8, 2012 at 5:01 pm


    I live in southwest West Virginia. I recently had a water leak that caused me to have to remove part of my hardwood flooring and replace it. Once the hardwood was removed, we placed 3 dehumidifiers in the 10×18 area along with 3 fans. Seemed like overkill to me, but that is what the insurance company contractor said needed to be done. These were allowed to run for about 3 days, and the floor sat unfinished for about 3 weeks after that. I have 1×12 subfloor layed on 45 degree, then 1/2″ plywood on top of that with tar paper between the two sub floors. There was no damage such as cupping, turned edges, or ply seperation to the plywood. The first week of December, I re-installed the 2-1/4″ hardwood flooring. It is tavern grade flooring so there was a few very, very, very small gaps on the end of a few of the boards where the factory cut was not perfect but overall the floor was installed very tight. I now see several joints widening. Most are of the business card thickness that you talk about, others are wider, some maybe 3 or 4 cards wide. The puzzling part to me is none of the rest of the floor that was installed a couple of years ago seperate like this. (This floor was installed in April which would be a more humid time than December in my area). I stacked the new floor up in an adjoining bedroom for several days before I installed it to “season” it to my house. I did not spread it out, but stacked the 10 boxes up 3wide and 3tall with the 10th box stacked on top. Is it possible that the floor couldnt get air to it to allow the humidity to get out of the wood before I installed it? I am getting ready to install flooring in another adjoining room and wondered what I should do to make sure the cracks do not appear in that room as they have in my dining area. For the record, I do have a heat pump which I know sucks most of the moisture out of a house in the winter.

    • Bill Hirsch | Architect Bill on January 8, 2012 at 10:54 pm

      Mark – It sounds like either the moisture content of the wood flooring or the wood subflooring was still not correct when the flooring was installed, or the difference in moisture content in the subflooring and wood flooring was too great. When you are “seasoning” the flooring, you should place sticks between the boards to let air flow all around it. This is called “sticking,” as you might have guessed. Without sticking, the interior boards in the stack could take a very long time to dry. There is really no way to predict the exact amount of time the wood should “season.” It all depends on the climate conditions. You’ll only know it done by measuring the moisture content of the wood with a moisture meter. Shoot for a moisture content of 8% to 10%. But don’t stop there. You also need to be sure the moisture content of the subfloor is within three percentage points of the wood flooring. If the difference is too great, you’ll get differential movement that will cause cracks later on. Chances are you don’t own a moisture meter. But you could borrow one from a flooring company or a good builder, or possibly even rent one. It will be well worth the effort.

  40. Mike on January 14, 2012 at 12:01 pm

    We had hardwood installed in the summer of last year now that it’s cold we
    See alot of gaps n wood. We can see them along the side of wood and at top of wood in some spots. Is that normal?

    • Bill Hirsch | Architect Bill on January 28, 2012 at 4:53 pm

      Mike – Gaps in the winter are normal. Very large gaps are not. If you humidify your house in the winter you will reduce the size of the gaps and possibly the number of them. They should all disappear in the summer. It’s just wood “doing its thing.”

  41. aaron on February 23, 2012 at 1:44 pm


    I purchased a new home, it is now 7 months old, and my expansion joint opened up a substantial amount due to concrete shrinkage.. this was found out due to tile grout completely being pulled up by my weekly cleaning of the home, the flooring guy came in and pulled sever tile up in the bathroom and kitchen to investigate the “crack” they placed a “special” thin set into the expansion joint and put a fibrous tape down before re installing the tile.. now my wood flooring has pulled apart @ the end joints across this same line thru the entire house… the gaps are 1/4″ to 3/8″ wide and to me un acceptable… they stained the 30 plus gaps and now want to use putty this is a 250k home and 7 moths old.. also this flooring is glued directly to the slab no sub floor… I need help and advice on how to keep the pressure on these guys to get this resolved.. they aren’t interested in fixing this issue..

    • Bill Hirsch | Architect Bill on February 26, 2012 at 11:57 pm

      Aaron – It may be difficult to actually stop this problem from continuing. It’s unlikely you concrete has shrunken that much. If it did, the concrete itself would be cracked dramatically. It sounds like they did not check the moisture content of the wood before installing it and it was too high. Now the wood is giving off its moisture and shrinking. If they did not installed a proper vapor barrier beneath the concrete slab and seal the concrete slab, the wood will keep on “wicking” moisture continuously. If the cracks eventually stablize, you could have them cut out a strip of wood at the crack and install a narrow strip of wood flooring to fill the gap and make it look purposeful. Filling with putty is not a good solution. The putty will simply squeeze its way out before you know it.

      You might check to see if your contractor is a member of a professional builders organization. If he is, you could take your grievance to them. Otherwise, there is the Better Business Bureau. They should be responsive to a valid complaint and the bad press it would bring. Good luck with this.

  42. Michelle on March 18, 2012 at 11:49 pm

    I recently had an engineered hardwood floor installed. It was installed using a floating floor method. The company that did the install also gutted and installed a whole new kitchen. I pointed out as they were installing the floor that the kitchen didnt seem level with the rest of the living room and was surprised they werent leveling the floor. They assured me it was not enough to worry about. Since finishing an almost 1/8″ inch seam has opened up in the hallway leading off the kitchen/living area.
    They assure me it is the “cold snap” that happened just after the install. I can fit 4 business cards in the gap and cant see any adhesive. There is also a couple of soft spots in both the hall and kitchen. The wood is hard up against the drywall all over the place and there is about a 1inch change of height over 9ft in the kitchen. I had a friend look at it who also told me that there is “stepping” and that the install has voided the manufacturers warranty on the wood.
    The contractor is saying its not a problem and he will fix the gap. He wanted to fill it with hardwood caulking and wait for warmer weather. I told him no I wanted it fixed not covered up.
    He explained the lack of 1/4inch gap between floor and wall as his guys way of locking the floor in place until the baseboards go on, at which point they would cut it and lock it down with the baseboards. This is also meant to fix the inch of movement in the floor along the wall edge in a cuple of spots.
    Interestingly enough I was going to be installing the baseboards myself and they had mentioned no such thing and the lack of gap is all over my apartment including under the door jams.
    My contractor also directed me to this article to help me understand the gap in my floor.
    I would love to hear your thoughts on this as I am beyond angry and dissappointed, I paid a huge premium for what I felt was a quality company and now I have doubts.

    • Bill Hirsch | Architect Bill on March 24, 2012 at 5:14 pm

      Michelle – It is hard to assess your problem from afar. Small gaps between boards that come and go with the seasons as the wood swells in summer and shrinks in winter. And with a floating floor where the planks are all glued together to form one large slab of wood, the whole group of boards could pull back from the existing floor and create a larger than normal gap in winter. It probably would have been a good idea for them to glue the floating floor securely to the edge of the existing floor.

      A floating floor installation for an engineered floor is normal. And gaps around the edges are necessary to let the floor expand and contract. Without the gaps, the floor would buckle when it expands in the summer and presses against the walls. The baseboards and shoe molding will cover the gap and the flooring will slide in and out beneath it. When it is all done, none of the gaps should be visible.

      Caulking the gap is a bad idea. When the floor swells it will simply squish the caulk back out. In old houses, large gaps come and go and people get used to them. With your new floor, the large gap means the new floor was not adhered to the edge of the old floor. The soft spots sound like the surface beneath the wood floor was not properly prepared and should have been patched better. I don’t know what material is beneath the wood flooring, but regardless, a one inch slope is an issue with the construction of the building. That is more than a floor installer would be expected to correct. But filling of irregular dips is something they should do.

      I hope that helps.

  43. " class="url" rel="ugc external nofollow">Darlene Bloxham on March 27, 2012 at 1:24 pm

    Hi Bill
    We installed acacia floors in our main floor 4 years ago. We live in Alberta, Canada, cold dry winters and dry summers. The floors were installed in December. In the following summer we had the installer come back and he used a clear filler at the entrance to keep dust out of the cracks. It dried up and came out. The floors cover our whole main floor including the kitchen. Cleaning is a challenge. We have to vacuum using a crevice tool and a skewer to get all the gunk from between the boards and mopping is difficult because we don’t want water seeping down between the boards. We have gaps between every board from 2 to 10 business cards thick. Sesame seeds and rice can easily fit between some boards. We simply cannot afford to replace the floor. We haven’t even considered insurance because we figure it wouldn’t be covered. For us (me) cleaning is the everyday issue. Any suggestions????

    • Bill Hirsch | Architect Bill on March 29, 2012 at 4:01 pm

      Darlene – I’m sorry to hear about your troubles with your floors. It sounds like the wood had much too high a moisture content when it was installed. Humidifying in the winter can help, but it sounds like this is such a large amount of shrinkage, even that won’t help. I don’t know of any fillers that will not squeeze out when the floor boards swell. But there are some that advertise they will do the job. My guess is the two-part type will ne toughest. Two-part compounds work like epoxy glues. When the two parts are mixed together, a chemical reaction occurs and the material gets very strong. These types of fillers would be trowelled across the floor like tile grout and pressed into the cracks. Then the floor will need to be sanded and stained to color the filler as well as the wood. I have never used any of these products so I cannot endorse any of them. But put on your detective hat and search the market for something like this. Then try some out in a descreet place. It sounds like you have nothing to lose with an experiment. Please let us know what you learn.

  44. Daniel on November 28, 2012 at 10:39 am

    Hi Bill,
    We just had 3 inch solid american oak installed in our floor: cement subfloor with radiant heating. They used the Sieka adhesive with sound barrier, a system that is supposed to permit natural movement. Immediately after installation and prior to sanding, we noticed gaps between the boards – enough for a credit card. In Buenos Aires, we have higher humidity now inside, but in winter with radiant heating, that moisture is cancelled. My worry is that if we start out with these gaps, we will be seeing enormous gaps come winter when the subfloor is heated. The contractor says it’s all normal, but I was still shocked to see a brand new floor already have gaps! There are also a couple soft spots where you can feel the boards flex downwards, as if there is space between the boards and subfloor. Again, this was installed a few weeks ago.
    Would appreciate any feed back.

    • Bill Hirsch | Architect Bill on December 8, 2012 at 9:10 pm

      Daniel – Did they check the moisture content of the wood before they installed it? They should have used a moisture meter with two prongs that are pushed into the wood. The Moisture Content should have been between 6% and 8%. If it was more than that, the boards will shrink excessively. A floating floor, as you describe, usually is installed with the boards glued edge to edge. That way the entire floor expands and contracts more or less as a solid entity. It is possible that your gaps will not enlarge with winter’s dry air. It may shrink as a solid unit without the gaps enlarging.

      There are too many variables for me to give you a definitive answer. See how things go when winter comes. If the gaps become really excessive, the only solution is to reinstall the flooring. And if you want to limit the shrinkage, use a humidifier to keep the relative humidity up in your home. It will actually make the house more comfortable and keep other things, like furniture and musical instruments from cracking.

  45. Tony on December 27, 2012 at 2:21 am

    Hello … my wife and I had a one-story home built this year and we moved in on November 11th. We live in Pennsylvania (east of Pittsburgh). There is a full basement and gas forced air … no humidifier. We had engineered hardwood installed and it makes all kind of noise … especially in the morning … sounds like your walking on sea shells and they are all cracking and breaking. Our Amish builder did not bring the wood into the house before installing. He stapled the hardwood but we don’t believe he did the job right. He has offered to come back and work from the basement to tighten the boards … but we have been told by a local contractor who lays flooring that our builder would not have much to work with since the thickness is only 3/8 inch. Would a humidifier take away the constant crackling or do you think that something else is wrong … and can it be corrected? Thank you. Tony

    • Bill Hirsch | Architect Bill on January 7, 2013 at 11:38 am

      Tony – Humidifiers always help wood floors. Keeping the moisture content in the wood stable will keep the wood from swelling and shrinking with the change of season. But some of your noise may be caused by the flooring not being glued down properly or with the right adhesive. I would suggest trying the humidifier first. And if that does not solve the problem, the only other thing you could do would be to pull the floor up and have it reinstalled with a better adhesive. Hopefully it won’t come to that.

  46. Dave on January 27, 2013 at 10:08 pm

    Hi Bill,
    Great site! I’ve gotten such an education today on hard wood flooring.
    I thought it would be easy to just buy, nail down and enjoy. I realize I have A LOT to think about and plan for. Almost all my questions have been answered except: when is the best time of year for me to install my 3 1/4 oak? I had planned on doing the job in Feb. We live in MA and have gas forced hot air. It does get pretty dry in the winter but for only about 3 months. During the summer, we have the AC on so the humidity is kept in check. I will go out and get a moisture meter and check the sub floor before I install and I know to keep the oak and the sub floor about the same. But what if the sub floor is too dry/wet and I can’t get it within range? Is there anything I can do about that? Thanks, Dave

    • Bill Hirsch | Architect Bill on January 29, 2013 at 2:47 pm

      Dave – I’m glad you like the website. Tell all your friends. 😉 The key with installing wood floors is to do it when the wood flooring and the subfloor have the same moisture content. That way they will move in a similar fashion over the seasons. It is best (easiest) to install wood flooring during Spring or Fall. That would be when the relative humidity is at its average point. But if the moisture content is controlled, you can install hardwood at anytime of the year.

      If your subfloor is too wet or dry, you can use a dehumidifier or humidifier to adjust the moisture content. This could take a week or two depending on the power of your humidifier or dehumidifier. And you should place the hardwood flooring planks in the space where they will be installed for several days or longer so they can acclimate to the humidity. That way they will match the moisture content of the subfloor no matter what it is. When you put the wood flooring in the room, don’t just put the bundled stack down on the floor as is. You need to open the bundle and put spacers between the planks to let the air get to all of the wood.

  47. Danny on February 8, 2013 at 9:27 pm

    Hi Bill,

    Great website! Lots of different information and this has me a little confused. I’ve read many of your replies and you keep saying not to fill the gaps, but I got to say I have cracks that are very thin and others where I can fit a penny without any trouble. The floor squeaks and I can feel it move down when I pass on some planks. Although the house was built in 2000, I bought it from the owners in 2010. It was not something we notice before buying, but on our first winter here, we notice shrinking and cracks. This year 2012-2013 the gaps are wider. Many sites say the shrinking will disappear with summer, but a good 20% of the cracks were still visible during the summer. Now my questions; should I fill the gaps during the summer? If I raise the humidity level will I get the gaps to close. I must say during the summer the humidity is low since we have are conditionning. Finallly, this question is not on the flooring, but the staircase, is there a way to stop the squeaking there too.

    Thanks in advance for your comments, suggestions and professional advice.

    Danny (Blainville, Québec, Canada)

    • Bill Hirsch | Architect Bill on February 9, 2013 at 1:08 pm

      Danny – It sounds like they did not have the right moisture content in the wood flooring when they installed it. The cracks would disappear in the summer, even with air conditioning, if the wood had not been too moist when it was installed. Now there is not much you can do to resolve the cracks. Keeping the humidity up in the house will help some. And if you fill the gaps with a filler, it is likely to work its way out as the wood moves with the seasonal changes in humidity. Very wide gaps can only really be fixed by replacing boards.

      The stair squeaks are caused by the parts of the stairs moving too much. If you can access the underside of the stairs, you could install shims, wedges, and glue to tighten things up. If the underside of the stairs is drywalled, it might still be worth it to rip out the drywall, fix the squeaks, and repair the drywall. If the sqeaks drive you crazy, fixing drywall would be a pretty easy solution.

  48. Danny on February 10, 2013 at 12:06 am

    Thanks Bill.

  49. Valerie on July 19, 2014 at 11:48 am

    Our home was constructed April through August 2013. It was a very rainy spring and summer in VA. Water and mold were present in the conditioned crawlspace prior to the completion of the house. Our wood floors were installed in late July. There were still moisture issues in the conditioned crawlspace. After moving in, we placed a humidity monitor in the crawl. It was in the upper 80 – 90s %. It took six attempts by the builder to repair the condtioned crawlspace in December 2013. He then ran a dehumidifier to try to dry it out for 8 weeks. The humidity level dropped to 20%. Huge gapping appeard throughout the house in the floors and moldings. The floor gaps were wide enough in places to insert 2 quarters and you could see the subfloor in places.Some gaps ran across the whole floor along the griders. Very noisy. Now that it is summer, the gaps lessened. However,the floors pop, crack, and move beneath your feet everywhere. Many boards have slightly popped up where they meet. There are sections over the girders that are bulging upward. Is there any advice you can give me. Tahnk you.

    • Bill Hirsch | Architect William Hirsch on July 19, 2014 at 4:33 pm

      Valerie – I’m sorry to hear about your floor problem. It sounds like the builder really messed up. Chances are there is no way to correct this problem without pulling up the wood floor and installing a new one properly. Your builder should be responsible for the cost of doing that. Hopefully he will stand behind his work and correct his error.

      • Valerie on September 16, 2014 at 12:35 pm

        Hello again Mr. Hirsch – Well, we paid for an NWFA certified inspection and he concluded that we have a pervasive problem with loose subfloors. The popping, cracking, squeaking and movement can be experienced in the carpeted, ceramic tiled and linoleum floored rooms, as well as the hardwood covered floors. He agreed with you that the only way to fix this properly would be to pull out the existing flooring, repair/replace the subfloors and then reinstall new flooring. He said that because the problem is so widespread, fixing it from underneath would be impossible- if you tightened one spot, you would just be shifting the problem to another area. I also spoke to an engineer from Weyerhaueser (the osb maunfacturer), and he said that what we experienced was the perfect set up for the osb to fail. He sent me their specs to back him up.
        We informed the builder and after a month they sent over two reps and a rep from the company that did the install. They claim that I unduly influenced the report by detailing the crawlspace problems.They are denying that the dampness and humidity issues are relevant and state that all wood floors have noise and movement because it is a natural product. No explanation for why we are having the same issues in the other rooms on the first floor. They are “working up a gameplan” to tighten it from underneath and claim that it will be fine. Your thoughts?

        • Bill Hirsch | Architect William Hirsch on September 16, 2014 at 1:22 pm

          Valerie – I’m sorry to hear that you are having so much trouble with the flooring and sub-floor. I don’t see how you “influenced” the report by detailing the dampness and humidity problems in the crawlspace. That is part of the overall conditions. Facts are facts. It is information that would be revealed if the case went to court. It is also something the subfloor manufacturer would certainly want to know.

          I disagree with the builder. All floors do not make excessive noise or have excessive movement. It sounds like you may need to talk to a lawyer about this. A lawyer with experience in construction claims might very well have run into this same problem in the past. I don’t see how the builder could possibly avoid his responsibility for this problem.

  50. Sandie Van Brederode on August 3, 2014 at 5:26 pm

    Hi there,
    I was reviewing on yours site about hardwood flooring having gaps over time. We have been in a new build for just over two years now and I am noticing random gaps in my flooring but they are at the ends of the planks. My house is usually pretty cool because of the air conditioning and we do use a dehumidifier if necessary. Should we run this in the winter time? Sould I be worried????

    • Bill Hirsch | Architect William Hirsch on August 16, 2014 at 3:37 pm

      Sandie – No. Don’t run your dehumidifier in the winter. In the winter, the outside air had very little humidity in it. When that air comes inside and is heated, the “relative humidity” goes down even more. So in winter, you would actually want to humidify the air and not dehumidify the air. By far the most shrinkage of wood occurs across the grain, not lengthwise. But some very, very slight shrinkage can happen in the long direction. However, my guess is those gaps at the end of the boards were there when the flooring was installed. You just did not notice them. Sometimes the ends of the wood were not cut perfectly perpendicular to the edges and the ends cannot come together evenly. But these kinds of gaps will not enlarge. I would suggest not worrying about them.

  51. Sue on September 14, 2014 at 10:24 pm


    This is my replacement floor, which my previous floor was installed with defects and show honored the claim . The new floor Anderson Casitablanca beveled was installed with same installer three weeks ago and now I started to see small gaps in many places, actually I am seeing the unfinished tongue in the tongue and groove joint between the boards. I am really scared as these gaps are more visible during the day time when direct sunlight come into my home and also in the night time for the light. This is a newly build home in Texas and I just moved in June 2014 and I went through so much to to replace this new floor.

    Any advice on what can I do in order to resolve this?

    Please help.

    • Sue on September 14, 2014 at 10:27 pm

      Bill, please help me on this.

    • Bill Hirsch | Architect William Hirsch on September 15, 2014 at 11:50 am

      Sue – It sounds like they installed it wrong again. If gaps are showing this soon, I suspect the installer did not check the moisture content of the flooring before installing it. It is likely the gaps will only get bigger as you move into the heating season when the relative humidity goes down and the wood dries out more. I would suggest you contact the manufacturer directly and get one of their representatives out to see it in person. They should want to know about the problem. This installer is giving their product a black eye. Good luck.

  52. Philip on June 10, 2015 at 6:42 am

    Hi, I installed an oak floor a few years ago. I have excessive cumulative shrinkage during the winter season. Initially this was not too bad however since new cavity wall insulation it has gotten worse. The cause is my own. Bad advise it would seem to install it as a floating floor and glue on the tongue and groove. So a large number of boards have grouped.

    My question Is this. To save lifting and replacing. Could I face nail the boards in the summer season when the gaps closee to prevent the cumulative shrinkage? Would this hopefully return the boards to shrink individually and therefore not be noticeable.

    • Bill Hirsch | Architect William Hirsch on June 12, 2015 at 1:34 pm

      Philip – If you face nail the boards when they are most “swollen” with moisture, they will probably crack when the moisture content in the wood is lower in winter. I say that because most construction adhesives (glue) are actually stronger than the wood. So the seams between boards would hold tight and you would get irregular and unpredictable cracks and splinters. That seems too risky to me.

      Instead, try thinking of your problem as a moisture problem and not a temperature problem. The boards shrink in winter because the relative humidity is very low and that draws moisture out of the boards and makes them shrink. I would suggest installing a humidifier and try keeping your indoor relative humidity at an optimum level throughout the year. If gaps still remain all year long, you could have a flooring person install slender strips to fill the gaps. If the gaps are only present in winter and disappear in summer, don’t fill them. Otherwise the floor will buckle when the boards want to swell in the summer months. Good luck.

  53. KES on July 18, 2015 at 5:53 pm

    We had a contractor install 3/4″ handscraped maple hardwood flooring in 2011. Last fall one section pulled up away from the sub-floor creating a hump that is parallel to the grain over the width of about 4 boards. Each is 5″ wide. Don’t know why this happened and do t know the proper fix for this. The remaining floors in the house are fine. Any advice?

    • Bill Hirsch | Architect William Hirsch on July 22, 2015 at 11:45 am

      KES – If I understand you correctly, your flooring has buckled. This happens when the floor planks expand too much. There isn’t enough room for the expansion and some of the floor boards are pried up, kind of like the way the tectonic plates in the earth’s crust collide and buckle up to form the mountain ranges. The cure for this might be to control the humidity in the house and floor. The floor might shrink back to a smaller size and then could be reinstalled. If that does not work or is not an option, you could take out one of the boards, re-size it to be a bit narrower, and reinstall it. This would take some craftsman skills, but it really would not be too hard. You would only need to take a tiny fraction of an inch off to make this work. It would be so little you would never be able to see the difference in width without measuring. Good luck.

  54. Sue Hume on October 31, 2015 at 7:10 am

    We just had Kentwood engineered acacia installed in our home. The floor has only been down 3 days. We have cracking and popping sounds throughout. Our installer said it will settle down. I am having my doubts. He put down new plywood underneath and some type of paper for moisture. He is a reputable installer and floors are beautiful.

    • Bill Hirsch | Architect William Hirsch on October 31, 2015 at 11:56 am

      Sue – Your installer is probably right. Wood changes it’s size as it changes temperature and moisture content. Newly installed wood takes a while to find it’s temperature and moisture content equilibrium. The sounds you hear happen when the wood moves even less than the thickness of a piece of paper! If the noises persist for months, then you might have an issue. But do not be concerned if a sound or two happen once in a while, especially during the change of season. That’s just your house adjusting with the climate.

  55. John on April 24, 2016 at 12:50 pm

    Thank you for this info! My hot water heater busted and now my hardwoods are buckling throughout my entire house. A apparently it had been leaking for weeks before it flooded the kitchen. Problem is, my old little English Tudor was built in 1923 so. As was standard at the time, there was no subfloor installed. Just the really thick tongue-n-groove oak hardwoods. On other interesting part is that the hardwoods go right underneath the walls. So when I do get this replaced, they’re gonna have to rip out the old flooring (I guess just cutting at the walls) install subfloor, and then the floors themselves. I have about 1200sqft of floor that will need to be replaced. If I went with an engineered hardwood (cuz I don’t want to go through this again!) at say approx 2$-5$ a sqft…..could someone give me a ballpark of what kind of total cost I could be looking at? Any advice or input is welcome and greatly appreciated!

    • Bill Hirsch | Architect William Hirsch on May 11, 2016 at 8:39 am

      John – They have saws that can cut right along the side of the wall. so they could remove all of the damaged wood and leave the portion of the wood the walls sit on. sorry I can’t comment on the cost. It varies from place to place and with the particular job conditions. Good luck with your repairs.

  56. Marla on January 5, 2017 at 12:21 pm

    Hi Bill, what a fabulous blog to really help people. We recently purchased an apartment in Toronto, Canada and our tenants complained that the engineered hardwood was buckling and gapping. We just had our insurance company assess it and their flooring specialist said the following:

    “There are numerous areas affected and he indicates that in his opinion the floor appears to be shrinking on the end joints of many planks, leaving some gapping, and this generally occurs with engineered hardwood when humidity levels are not stable. However, in order to fully establish the cause he indicates that he would have to lift up a few of the floor boards to investigate further.”

    I read through many of your answers in the comments section above, and in one of them you said that engineered hardwood shrinks across the grain, not so much in length. I have 2 questions:

    1. Is it possible that humidity could cause such widespread shrinking in length like the situation described?

    2. What will they be looking for if we decide to have them pull up the floor? Will that determine the cause?

    Many thanks for your time.

    • Bill Hirsch | Architect William Hirsch on January 16, 2017 at 9:53 pm

      Marla – Sorry to hear about your problem. Solid wood will do virtually all of its shrinking across the grain and essentially none in the length of the grain. The reason is that the wood fibers do not shrink. But when moisture come out of the wood, the pores in the wood between the fibers shrink. That is, the spaces between the rings of the tree shrink. With engineered wood, each layer of the plywood core is turned ninety degrees to the previous layer so the fiber of one layer resists the shrinking of the layer beneath and above it. That makes the wood quite stable. I suppose that even with the opposing layers, if the wood had a high moisture content when it was installed, it could shrink later. So it is a bit surprising, but possible, that the flooring is shrinking lengthwise. However, normal conditions would probably not cause this problem.

      If the wood is actually shrinking, it would usually happen in winter when the humidity is very low. Installing a humidifier can help reduce the shrinkage. And the flooring would return to its original size when the humidity goes up in summer. Buckling would usually happen when the wood gets too wet and absorbs water. If you have buckling and shrinkage, it sounds like the floor might have been flooded at some point. Maybe a dishwasher sprung a leak some time ago, water at on it, got under it, and was absorbed into the flooring, thus the floor became damaged. That would be my first guess.

      When the inspector takes up the flooring, he might be looking for some areas of excessive moisture in the underside of the planks indicating that the flooring got water damaged at some point. But it could have dried completely by now. No matter what he finds, it is a good bet that the floor was once laying down properly and something made it move, buckle, and shrink. I’m betting on the flood scenario. Your only option is probably to replace it. If and when you replace it, consider the engineered flooring with a thick top flitch (layer.) These are a lot more durable than the ones with thin top flitches.

  57. Jeff LiPira on January 12, 2017 at 7:24 am

    Bill, I have been reading through most of the other posts and I think I may know what the problem is but don’t have a solution. I purchased a home that had a hump running through what I thought was just the family room wood floor, directly over the steel I-beam in the basement. After moving in, I noticed this hump extends through the entire house on both floors over the length of the Steel beam. The problem gets worse in the winter, but never completely goes away in the summer. I also noticed drywall repair along the support walls above the steel beam where the “hump” goes into the wall. I took a RH reading in the winter and it was from 21-25% when the temps were low enough for the furnace to run. Would a whole house humidifier help my problem, or does this sound like a structural issue? If some of this was the house initially settling, and the seasonal movement gets controlled, can a good floor installer level this out?

    Thanks! Jeff

    • Bill Hirsch | Architect William Hirsch on January 16, 2017 at 10:14 pm

      Jeff – This sounds like a classic case of the central steel girder having been set a bit too high. The subfloor is probably right down on the top of steel. It would have been much better for them to set the top of the steel a bit lower than the top of the wood floor joists. New wood framing always shrinks a bit after the house is occupied and the heat is turned on. So the floor joists shrink, but the steel does not. This leaves that small hump you describe. In winter it gets worse because the wood floor joists shrink even more as their moisture contact goes down. Then in summer, the moisture content in the wood goes back up with the higher humidity levels. So a humidifier would reduce the problem, but not fix it completely. You probably need to take up the wood flooring at the hump, cut out and remove or grind down the subfloor to level it out, and then reinstall the flooring. Good luck with this. I hope it works out for you.

  58. Cara on January 8, 2018 at 11:22 am

    HI Bill,

    I have a question. We just had 5″ Mirage engineered wood floors installed over hydronic radiant heat floors. We are on a slab with our hydronic radiant heat. The manufacturer said it was fine for our radiant heat. We are noticing long cracks in the length of some of the boards. Is this a manufacturer issue?

    • Bill Hirsch | Architect William Hirsch on January 16, 2018 at 8:55 am

      Cara – Even when floors are installed with the right moisture content in the wood, they will shrink somewhat in winter when the humidity is very low. You will have small gaps in winter. However, the gaps should not be huge. You should not be able to fit a coin into the crack. The gaps will disappear as the seasons change and the wood absorbs moisture from the more humid air.

  59. Anabel Puckett on February 18, 2018 at 10:25 pm

    Thanks for sharing such relevant information about gaps in hardwood floor.

  60. Paul on July 5, 2018 at 10:40 pm

    Very interesting article, keep up the good job!

  61. Aldwin Graham on September 28, 2018 at 12:29 am

    Thank you for this informative blog. Use wood filler or epoxy to replace any pieces of the desk that have broken or rotted off. Use a putty knife to apply filler to the area in question. Shape it with the knife, toothpicks, or any other tool that might come in handy. Allow the area to dry before moving on.

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