Thinset Over Painted Floor

This surface is called a scratch coat.

Thinset over painted floor.

Whether you have cracks chips or just a stained concrete slab thinset helps cover the old surface and create a new problem free area. Thinset tile mortar has a smooth slippery consistency similar to mud. Apply a coat of sanding sealer or tile prep sealer to the floor with a paint roller. A latex based thin set adhesive should be used over the latex based paint.

Paint used on concrete will not bond with the tile adhesive. Mortar cannot be installed directly over painted concrete itself. Installing tile over painted concrete adds a few extra steps to your tiling job. Thinset is a mortar that is made of portland cement silica sand and moisture retaining agents.

The floor is a 4 inch poured concrete slab over an unheated utility room. The thin mix is laid over. The house was built in the late fifties and the slab floor has been painted at least once. Unfortunately the tile cannot be adhered directly to the painted surface.

The painted surface has to be cleaned properly to ensure an adequate bond. A scratch coat will give the mortar something to hold on to instead of the layer of paint over concrete. Thinset mortar is your default tile mortar for most indoor and outdoor applications. If the paint is not well attached then as the thin set adhesive dries and shrinks it might pull the paint loose.

Only use epoxy and latex thin set products that state they can be used for bonding tile to paint. First a surface more textured and solid must be applied over the painted concrete.