(Dirt) crawl space causing waves and humps in hardwood floor

Q: Our hardwood floors are wavy, and in some places have humps in them. We have lived in this house only 5 yrs. It was a new home and had no problems until last summer. I called and got advice and installed a dehumidifier in the crawl space. This thing runs all the time. Last summer water was dripping off ducts, no doubt it was moisture. So here is the problem: my floors won’t return to normal.

Rh in home is 53 and under home 55. This is Alabama, so it gets really humid. Any advice? Would a dehumidifier upstairs help? Should I run the AC more often? (we keep it at 75 to 77 most of the time.)

Is it time to sand down? Although the big humps may be from the subfloor, who knows.

A: If it’s a dirt crawl space I would definitely lay a heavy tarp over it and ventilate the crawl space so you can get air exchange in there. A dehumidifier on the main floor couldn’t hurt.

Similar Q: My grandparents home was built in the early 50’s, in southern Louisiana. It’s a wooden home built off the ground. The crawl space is only about 2 feet and the problem is the flooring. It is hardwood covered with plywood and commercial tile.

The tile is cracking, and the plywood is wavy. It looks like water damage, but it’s throughout the house. There was a leak under the house about a year ago. All the plumbing is under the house. There are no signs of additional leaks. The crawl space has been closed off on the North side of the house to help with winter heating. Parts of the ground are moist, some are not. What could be the cause of this flooring problem?

A: I’m not sure why someone would cover hardwood with plywood and tile, both of which are of less value than the hardwood floor?

You need to control the moisture from beneath the house. Heavy tarps over the dirt is a good place to start. Make sure the area is ventilated. I don’t know if the hardwood can be saved, but I would remove all floor coverings down to that and take it from there.