Should I level my basement floor if installing a subfloor?

Question

I'd like to install a subfloor in my basement including that dimple stuff to allow moisture to dissipate. Currently, it has sheetrock walls and trim with painted concrete flooring, but that's it.

A month after we moved in, our sump pump failed, and I got to see where 1-2" puddles of water collected in the basement.

This told me the basement flooring is not completely level. As far as I know, most basements are supposed to have a slight slant toward the main drain, but mine had a few puddles in different spots and one larger area notably dry. These weren't all aimed at the main drain so I don't know what to do.

Should I level the concrete or just install the subfloor and not worry about it? Are there any issues I could run into by installing the subfloor without leveling?

Answer 1

How old is the house?

This sounds like an old house given a 1-2" deep puddle and painted concrete.

You should consider that : - the slab is probably too thin - inadequate drain rock under the slab - no insulation under slab - lack of radon / vapor barrier under slab - the exterior perimeter drain may be clogged - sewer service pipes in slab may be close to lifespan - consider a backup sump pump on a hydrocheck HC6000v2 (non mechanical float)

How long do you plan to keep the house and how large is your budget and timeline? Doing this properly can be expensive.

Quick and Dirty would be to level it to within 1/2" over 4'. Certainly fill any depressions. Choose a waterproof vinyl plank flooring. I like the 6mm duraclic from lowes. You probably want to put down a 6mm poly vapor barrier under the flooring and tape seams to keep out radon. Having gone down the high end path before quick and dirty appeals more and more to me.

If the house is newish and all the above items to consider are good and you have budget you could take the pro approach and flood the entire floor with self level. This will yield the best result but is the most expensive option. Have to worry about door heights, etc.

Answer 2

I probably would fill the low areas to prevent trip hazards but also probably would not put anything down other than indoor/outdoor carpet a power outage or another pump failure and then any new material other than designed for wet dry will hold more water even with a proper slope . So yes fill the low spots , but reconsider any type of structure that another flood would ruin.