Filling voids under new engineered hardwood floor ??

[Perry Holbrook]

We just finished installing an engineered (plywood) hardwood floor. The sub floor was a combination of clay tile, tongue and grove 1 x 6 and OSB (2 additions). We were advised the warranty on the floor would not be honored unless we floated the entire floor.

I don't usually like the float application because they tend to make the floor a little springy when you walk on them. But on the OSB and T & G section the floor is very solid. The clay tile section was only 4ft x 8ft but had a slight slope and one large crack that created a bump across the 4 ft width. I used and underlayment skim coat to smooth that area and did the best I could to get it level.

However, I have a spot near the bump about 2ft wide that has a void between the floor and the tile, I would guess maybe 1/8" inch in the middle of the spot. It is in the highest traffic area of the floor so I want to fix that spot. The plan is to drill a small hole in the floor, inject something that will fill the void and then plug the hole.

I was thinking some type of epoxy that will flow into the cavity. My helper is suggesting the low expansion Great Stuff spray foam but I am afraid that could still expand too much.

Ya'll got any bright ideas?

[Wayne Lomman]

Avoid the spray foam. It is ok in static environments but your high traffic will cause it to fail after a time as the foam will break up. Inject epoxy or grout at intervals to simulate the joist spacing. Cheers

[Rich Engelhardt]

Is there any way to get at the spot from underneath?

[Perry Holbrook]

Is there any way to get at the spot from underneath?

Nope, afraid not.

[David T gray]

dritec makes a injectable glue worked great on my floors

[Lee Schierer]

Floating the floor means that the engineering product should not be glued or nailed down to the sub floor. The flooring needs to be able to expand and contract with seasonal temperature and moisture changes so there should be a gap along the walls all the way around so the floor can move. Minor gaps in the sub floor should not be a problem. Any humps or dips will be transmitted through the new floor so they should be eliminated as much as possible. Your 1/8" gap is too small to be of concern.