Basement floors
Can a basement floor be coated?
Yes, and what decides it is what the slab reads for moisture, because a basement floor sits in ground that holds water against the concrete all year.
The short version
- A below grade slab is the hardest moisture case in the trade, because the dirt around it stays damp.
- Older basement slabs were often poured with nothing under them to slow water coming up.
- The slab gets tested before anybody picks a system for it, and the reading changes the system.
- Water actively coming in at a wall, a joint or a crack is a water problem first and gets solved first.
- This is a floor you live on, so texture, gloss and the edges matter differently than they do in a garage.
What the moisture reading decides
Concrete on grade carries water up through itself, and a basement slab has more of it to carry than any other floor on the property. The ground around it stays damp, and on an older house there is often nothing under the slab to slow that down. So the first thing anybody does in a basement is test the concrete.
What the reading changes is usually the system rather than the answer. A slab that reads low takes an ordinary build. A slab that reads high needs a system chosen to sit on a floor that is still passing water through itself, and that is more material and more time. Somebody who skips the test in a basement is guessing on the one floor where the guess shows.
When it is a water problem first
There is a difference between a slab that reads damp and a basement that gets water in it. A puddle after a storm, a dark line along the wall where the floor meets it, or a spot that darkens every spring is water moving through the house, and that is a drainage question before it is a coating question.
A coating is a finish. It is not a way to keep a basement dry, and putting one over an active leak hides the leak and then lets go where the water is. Have the grading, the gutters, the drain tile or the crack looked at by somebody who does that work, and coat the floor once the room is dry.
Finishing a floor you live on
A garage floor gets looked at standing up with a vehicle on it. A basement floor is a room you sit in, in socks, with furniture on it, so the finish is judged from much closer. That moves the flake size, the color and the gloss, because a heavy gloss in a room with small windows shows every footprint on it.
The edges are the other change. Where the floor meets a finished wall, a stair stringer, a floor drain or the doorway into the mechanical room, somebody has to stop the coating by hand, and those lines are what you look at every evening. Ask how each one gets finished before the work starts.