One side of floor is heaving

Q: My sister has 3/4” hickory installed throughout her house. Only one side (west) has heaved horribly at both corners of the room. When I talk about this floor heaving I’m talking 6 inches to a foot at peak. Extending a good 8 feet long by 4 foot wide. One area 6 weeks ago and now the other corner area today.

Swamp cooler in smaller 1000 sf home. Subfloor remained in position on both ends (I’m The one that removed some wood planks). No moisture visible.

Here’s all the factors: The hickory plank does not appear to be nailed or adhered to subfloor. It does appear the planks were toe nailed together. Vinyl flooring remains on subfloor as it was original to home. No moisture barrier. Crawl space below entire home. Original foundation 1940’s, house was burned down and new ranch built using old foundation. The home is at bottom of high hill. This entire area was at one time a river bank. It’s an old neighborhood with a lot of newly constructed homes going on, all construction above sisters evaluation and on both sides of street.

She has had this floor down for a good eight years no problems tell now. What do you think is going on? Any advice would be greatly appreciated!

A: It may be water is running under into the crawl space. Perhaps someone needs to go under if possible and check the soil and the structure for rot. A heavy tarp over the soil can help as can water diversion if a hill is near that part of the house, directing water toward the building. Moisture has to be an issue because the floor planks are expanding. That is why the floor is heaving. You need two items to do some checking: a moisture meter for the hickory and sub floor. A hygrometer especially to test the temperature and relative humidity in the crawl space. The difference in moisture content between the hickory and the sub floor should not be more than 4%. 7-9% for the hickory would be good. When you start getting readings of 15% and above it indicates excess moisture and this is coming from beneath. There is of course another possibility. Water could be coming in for example around windows, running down the wall and under the hickory. That you don’t see water doesn’t mean it isn’t holding a lot of moisture.

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