Had a big problem with a glue down job in a Phoenix kitchen last month

I was putting down some sheet vinyl in a kitchen remodel, and the concrete slab felt dry when I checked it. I spread the adhesive and laid the vinyl, but the next morning the whole floor had bubbles and waves. The homeowner was really upset, asking me what went wrong. I pulled up a corner and the concrete underneath was still dark and damp. I guess the slab had moisture coming up from below that I didn't catch. I had to pull up all the vinyl, rent a big fan to dry the slab for two days, and then start over with a moisture barrier primer first. It cost me a whole weekend and ate into my profit. What's the best way you guys check for slab moisture before a glue down job?

2 comments

2 Comments

river_wright2d ago

Matthewbarnes has the right idea with the plastic sheet test, it's a solid basic check. The thing is, in a place like Phoenix with that dry heat, the surface can feel bone dry while there's still vapor drive from below. A plastic sheet alone might not give you a number. I use a cheap calcium chloride test kit for any glue down now. It gives you a real moisture reading in pounds per square foot. It's a bit more work but it saved my butt on a bathroom job last year where the plastic looked fine but the test showed high moisture.

matthewbarnes2d ago

That "dry when I checked it" feeling is the real trap. I've learned the hard way that a simple plastic sheet taped down overnight tells you way more than your hand ever will. It's cheap insurance against exactly this kind of redo.