Bill,
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

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.

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?

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

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. 🙂

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.

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.