Rushed new floor is cupping

Q: Last December ’16 we had a new subfloor and 3/4in oak floors installed in our dining room, to replace a floor that had buckled. Also in 2 bedrooms we removed carpet to find oak floors there too. We had a few boards replaced because they had been pulled up in the closets during previous remodel.

It’s Nov ’17 and about 4 months ago the new floor is cupping as well as the replaced boards in the other rooms. The older boards are smooth. I’ve read your other responses and was wondering if the new boards weren’t acclimated long enough and are perhaps drying on the top first, causing the cupping? It just seems odd that they replaced boards are cupping, but not the old ones.

The house has an open crawl space in Louisiana, so humidity can be an issue, but was not before. Should I contact the installer?

I am planning on getting someone out to confirm underneath is dry enough to install closed cell spray foam for a moisture barrier/insulation.

A: I would definitely contact the contractor. Did he do a moisture check on the sub floor, comparing it to the moisture content of the flooring? The readings should be within 4% of each other. Given your location I would likely have given the flooring at least a couple of weeks to become familiar with it’s new surroundings.

Follow-up: I don’t know if he checked the subfloor. We had flood damage in the August ’16 rain event in Louisiana. Our house is on 2 levels. One on a slab and the other, older part with the wood floors, is about a foot off the ground. The upper part didn’t have water on it, but there was water under it for about a week.

I’m afraid it was my fault to rush the job after the tear out, because we wanted back in the house by Christmas. Had I known I would have just thrown a rug over the sub floor and waited. He did put down a tar paper moisture barrier.

I bought a humidity gauge and moisture meter just yesterday. I want to determine if it is dry enough to refinish or if we need to wait. Do you have a suggestion as to the readings I should be looking for?

A: What are considered ‘normal’ moisture readings in oak are 7-9%. If you get readings of say 15, it is still excessive.

Follow-up: I am getting 9-11 reading and 62-66 on humidity in the house. Which is too high, but down here where outside humidity is in the 80s it’s gonna be hard to bring down. Hopefully when I get the subfloor insulated for moisture that will help.

A: The readings you are getting on your floors now are not bad at all, especially given the humidity levels there. It may be the floors were not adequately acclimated before installation. And if it was soaking wet in the crawl space, especially without ventilation, some of that moisture is going to work it’s was up through the bottom of the floor. Hence, the cupping. Many years ago I worked with a group of guys who prided themselves on how fast they could do a job, start to finish. We walked into a nice house on the Scarborough Bluffs, overlooking lake Ontario. We took the new, unfinished hardwood inside and installed it immediately, followed by sanding, staining and finishing. A couple of weeks later the call came that the entire floor had seriously cupped. It had to be sanded over from scratch. It’s a good lesson.

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