I installed 7" wide engineered floating bamboo floor over concrete. The floor was installed over a vapor barrier/foam padding. Certain areas of the concrete floor were not level and now the floor moves when we step on it because it is not contacting the concrete.

Can I drill some small holes through the floor boards and inject some expanding foam beneath these boards to fill the void?

Or is there another way to fix the problem?

Thanks

We used gorilla glue on one we went and looked were the installers missed as small area when leveling. We injected the glue and a little water to activate it, we placed a piece of tape on floor drilled through it and left it there to catch the excess glue as it expanded. It may not be the "right" way but it worked well.

Chances are the glue would not hold. The best fix would be to take it up, level the floor and relay.

Please realize that gluing is not possible as directly underneath the flooring is a layer of foam/vapor barrier and then the concrete under that.

That's why I thought injecting a little expandable foam would keep the floor from bouncing- the floor is level and is not coming up, just has a little bounce to it.

On a similar post on another forum....you don't want to use glue under a floater it will lock in the floor allowing no movement.

Best surfire way to fix would be to remove the flooring, level out the low spots and then reinstall flooring. Depending on where the low spot is, you may not need to remove all of the flooring to get to it. Drilling a hole to inject expandable foam may be a can you don't want to open!!Hope this helps. Or I guess you just live with it if it is minor

Eventually the movement will cause the tongue and groove to weaken, with traffic.

Pull the floor apart with a Board Bully.
Remove the planks over the low spot. Flatten the low spot with sand or filling compound( let filler dry thorughly).

Or put furniture on the low spots.