Hi all,

We had a water leak in our house and took the opportunity to remodel the entire first floor. The old floor was hideous 24x24 ceramic tile, and I always noticed some hollow spots under the tile. I thought it could be cracked cement slab under the tile. We removed the tile and the slab was in perfect shape - no cracks. They did say the tile came up pretty easy in some places, so I thought it was just installed improperly (many things in this house were done incorrectly over the years).

We selected a new engineered hardwood floor (wide plank) and they installed it while we were out of town. Once the baseboards went in, I noticed that there were some uneven gaps under some of the baseboards. We also recently had a new mantle delivered, and while it was sitting on the floor, I noticed that there were some gaps between the floor and the bottom of the mantle, which made me start to worry that there was substantial unevenness to the slab.

I couldn't get the photos to attach to this post, but they are viewable here:
https://paste.pics/GQK6W
https://paste.pics/GQK70

I am also now noticing that there are many very hollow sounding spots throughout the entire first floor. It is random, but I used a rubber ball and bounced it. Some areas sound fine, some sound hollow and some sound VERY hollow. In some areas, the ball didn't bounce as well, making me worry that perhaps there is some play to the boards in those areas.

I can't tell for sure, but there might be a board or two that might move slightly when I put weight on it. One board I can feel the slightly raised edge disappear when I step on it, so I am assuming that one is very slightly squishy.

I spoke with my GC tonight who said they used a lot of very expensive adhesive on this floor and that it should be fine. She also said that the cement slab wasn't perfectly level, but that they really couldn't do anything about it because it would require pouring cement to fix it, which doesn't seem right to me. From what I have read, they could have ground down high spots and floated depressions.

Anyway, I am hoping some of the experts here can shed some light on this and point me in the right direction. Should I get another flooring company or a flooring inspector out to take a look at this? I dread the thought of having to re-do the floor, but I want to make sure it is right and that this won't cause problems down the road before we begin to move furniture back in.

Does the perception of uneven flooring, uneven gaps under baseboards and hollow spots pose a big concern? Do I need to do more investigating?

Any advice or suggestions would be greatly appreciated.

Thank you,
David

Hollow spots may not have good glue contact, or no contact at all.. If the floor is supposed to be glued down the contractor needs to get some glue under the flooring so problems do not occur in the future. Mark the problem spots with sticky notes so the contractor can address these areas. Wide planks do not conform to an uneven slab as well as narrow planks, or short boards. This is always an issue when the slab is not as flat as is recommended. A thick layer of glue is not a good remedy for poor preparation of a slab. There is a recommended trowel for spreading the glue so it works adequately.
It is not unusual to have small gaps under tall base boards. A block plane could have been used to plane the spots where the base board touches a bump in the floor as the base is being installed which is better than trying to fill the gaps with caulking. The extra time required can make the difference in the cost of the job between making a profit or not. Often it is not in the budget.