Normal temperature for the finishing

Q: I’ve just had an underfloor radiant heat system installed under my existing and newly rewoven/patched oak flooring. The reweaving/patch was due to interior walls being removed. A low gloss oil based polyurethane was applied to the floor. Some nails that were protruding below the subfloor were cut so that the radiant pipe wouldn’t be damaged. They had to refinish the floors a second time because they were rough. Now the edges of some planks are peeling, especially in the hallway.

The contractor claims this is occurring because the nails were cut. But it’s happening in a room that didn’t have nails cut. The radiant system hasn’t been turned on yet. It was cold, about 50 degrees in the house when they polyed but about 30 outside. I don’t know if they used a sealer. What should he do to fix the problem?

A: 50F is far too cold to be applying a floor finish. There is no way any of the coats could have been dry enough before applying another. I am very surprised the finish didn’t wrinkle. I would have the area at normal temperatures for at least a month and then have the floor vigorously buffed and coated again. Fingers crossed, hopefully this will fix the problem.

Follow-up Q: Thanks for responding. I had noticed that they had just brought the poly in from the truck. I guess that it should have reached a normal temperature also. In your opinion what is a normal temp? I think they may have used a sealer before the poly coat. They also just used clean(?) rags with,I believe, turpentine to clean the floors. It seems that tack cloth isn’t something they use.

I guess you think, as I do, that the grinding of the protruding nails was in no way the cause of the edge peeling.

A: “Normal” temperature for the finish would be 70F or warmer. If it has been left out in a truck in freezing weather, it would take probably a full 24 hours to get it up to where you would want it. I would suggest wiping a floor down with either a micro weave mop or a towel dampened or squeezed nearly dry. Wrap it around a push broom and go up and down the floor. Make sure the water is dry before coating. Here is a heads up I only recently found out about. Products such as mineral spirits/varsol and I assume turpentine, might be recycled and contain contaminants that will cause adhesion issues. Buyer beware. Poloplaz, the company I now purchase my floor finishes from sells “virgin mineral spirits”. To avoid all this, tack with damp towel or appropriate tack cloth.

No, I wouldn’t attribute grinding the nails to the edges peeling. what can happen however, is that the nail head is totally sanded off and no longer supports the board to keep it stable. During intercoat buffing, the board may flex and not get buffed at all, and you stand a chance of loosing adhesion on any areas like that. If there is a lot of flex between boards, I could see the finish stretching and cracking off along the edge, but not peel. It won’t peel if there are no contaminants and the previous coat was abraded or scratched.

Similar Q: What tempature does a wood floor need to be to apply polyurathine? This is in a room built off a deck, not yet insulated. I’m about to put polyurathine on and it has been 40 deg at night.

A: As close to 70 F as possible. 40 F isn’t going to cut it.