Filling a void under Hardwood Flooring

[Lauren189283]

Hi there,

I recently bought a home and there is a gap between the hardwood floors and the concrete foundation (where I assume a new slab was poured later on, looks like garage or carport converted to living space). The boards sag a fair amount when you step in the area. The hardwoods are super nice, and I have no Idea the brand, so ripping out the section and self-leveling would mean redo a lot of area, which we don't have the budget for currently. they are 3/4" x 3 1/4" boards.

I was wondering if drilling small holes are filling the void would be the best option. I have heard people mention Great Stuff, Epoxy, and Tile adhesive to help level the floors. I think Great Stuff (window and doors) would fail pretty quickly since it's a high traffic area.

If anyone has advice on this, it would be greatly appreciated!

 

[mike93lx]

IMO, something expanding is a bad idea. Self leveler is the ticket. How is the floor adhered?

 

[Lauren189283]

It's glued down to a padding. Goes concrete, moisture barrier, pad, glue, hardwood.

 

[larry4406]

I had this used once on engineered wood floor on wood sub floor to fix a hollow void.

They drilled a small hole at joint then injected it in.

 

[PugetDude]

Squeeze it in, step on it and watch the excess spurt back up out of the hole.
Mask and cover the floor surface....

 

[larry4406]

Squeeze it in, step on it and watch the excess spurt back up out of the hole.
Mask and cover the floor surface....

The one I was involved with, I don’t recall them stepping on the loose board. As they injected it in, it certainly came up in several other nearby seams which they wiped off.