I am interested in tiling over a concrete slab, which has been painted. Last year I ran into a similar project, where I used paint stripper to remove most of the paint, and then rented an orbital floor sander to clean up most of the floor. Is this necessary, or can I tile right over the paint?
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What kind of paint is it: Drylock, latext, polyurathane garage floor paint?
The paint is latex.
Read the directions on the bag of thinset. They ought to tell you what a suitable or unsuitable substrate/surface is. If not, then I'd contact the thinset maker and ask.
Tiling over slab.
Don't tile right over the paint unless it's well adhered to the concrete. If it is, start by pressure washing the floor to remove any loose paint and general dirt (make sure there is a floor drain....) Then, scrub the slab with a water and TSP solution to remove
grease, etc, and rinse very well. Let the slab dry properly. Check the tile mortar instructions - it may a require a specific primer to be installed over slab. This may be important as the slab (unprimed) may absorb a lot of the thinset moisture and cause problems with curing and adhesion.
Eric
Thanks for writing, Eric. The pressure washer is a great idea. Unfortunately, the area in question is a finished room, so there are no drains present, and the walls are drywall. Any other thoughts are greatly appreciated.
Be REAL careful with that pressure washer.
Maybe go back to what they had before pressure washers: stiff wire brush and elbow grease.