In May I had about 1,000 sq. feet of engineered flooring installed (glued down over concrete). The installers did not adquately prepare the cement floor and I have many areas that are hollow sounding and squishy. I realize that the floor won't be perfect and some hollow spots will occur but how many are too many and need to be brought to the flooring store's attention. I would guess that I have at least 20-30 squishy areas. What can they do to correct these spots (injecting glue?)short of redoing some of the areas and is the cure worse than the problem? What will happen if these areas are not corrected. I live in the Orlando area and should have had Sean install it. By the time I learned about Sean, I had already put some $$ down with the flooring store but knowing what I know now, I should have cut my losses then!

I can walk into any gluedown and if Isearch long enough, I will find a hollow spot.

If I find more then a spot, and it becomes and area larger then 1 sq.ft. then it is a problem. Same as if I find many hollow spot is a problem. 1 per 200 sq.ft. no bigger then 1 sq.ft. each is not a problem.

If it flexes, that is a BIG problem.


Injection works if the guy injecting, knows what he is doing.

I have seen a messed up floor with drilled holes all over the place just to fill a small spot.

20 to 30 is 20 to 30 too many.
Hard to tell from here, but your description is that of a slab way out of tolerance for flatness. Not serviceable if you can see and feel high spots in the slab.