Q: I installed bamboo engineered click flooring on my garage floor that was converted to a media room. Floor wasn’t completely flat in a couple of spots…there is a cushion of air that you feel about 2′x3′ in diameter and about 2′ from the edge of the floor. would a humidifier help the floor conform to the concrete, maybe some weight on that area? I also think i might have installed a couple of warped boards…only about 2 of them…my end gaps keep appearing after the floor is walked on. thanks for any help.
A: Before we get into the problem occurring let me first stress that you do NOT use a humidifier in this room. Adding moisture to the floor will cause it to expand and most likely begin to buckle or warp if it absorbs too much water, getting above about 8-9% moisture content. Also, I would not suggest putting weight on the floor sitting over this valley in your subfloor.
The right way to fix this problem would be to remove planks of flooring (which is much easier since it is a click) until you uncover the 2′x3′ valley in your subfloor. Then, level this area out using a self-leveling compound. Once this compound has cured, reinstall the bamboo planks.
The gap you are encountering is happening because the floor is flexing down into the cushion of air you describe. This area is larger and deep enough to cause enough movement when weight is applied to the floor that it is flexing and creating this gap. The only way to actually fix this problem would be to fix the subfloor by leveling it out, or to get a shimming material into the valley to help support the floor.
Here are a couple of photos that were sent a long to illustrate the gap that is happening:
In this photo you can see the gap in the center and the substrate below the finished bamboo surface.
Here in this photo you can see where the floor is flexing over the valley in the subfloor being described. The two lighter colored planks below and to the right of the gap can be seen slightly lower than the rest of the floor.
