Marsha wrote:
We have an addition on a crawl space. The crawl space is about 3'
high. Underneath on the ground is rock dust with plastic sheeting over
top. The spaces between the joists are insulated.

We had hardwood flooring put in the addition. Within about 6months the
planks are cupping. It's very slight but it is noticable (at least to
me). What is causing this? Everyone I've asked always says "is their
plastic underneath covering the rock?" the answer is Yes. Then they
don't have any other ideas.

Does anyone out there have any idea what caused this? The worst
cupping is going on in the entry part of the new addition. There's a 6
foot opening to walk through. The flooring right in this obvious area
is the most noticeable. Most of the room is covered with an area rug.
What's under the area rug looks ok.


I think you should have a moisture barrier between the flooring
and the insulation. That will keep the humidity and temperature
on both sides of the flooring approximately equal.

That may be the case already, but you didn't say.

If the flooring is concave up, then the air in the room is drier than
the air in the crawlspace and vice versa.

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FF