Thinset Over Painted Floor

Not that they would endorse going over an oil based paint what you should do is scarify the paint off the floor.

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. First a surface more textured and solid must be applied over the painted concrete. Tile adhesive is expected to hold the tile in place not just for years but for decades without fail. The house was built in the late fifties and the slab floor has been painted at least once.

How to use thinset morter to resurface concrete. Paint used on concrete will not bond with the tile adhesive. It must be easy to work with and it must adequately fill in gaps between the tile and the substrate. A scratch coat will give the mortar something to hold on to instead of the layer of paint over concrete.

Tile cannot be attached directly to painted concrete as the thin set will not adhere well to the paint. Whether wall or floor tile that tile needs to thoroughly stick to its base surface demands placed on tile adhesive are both extensive and steep. Tile will stick to most rigid level surfaces including painted wood provided the correct preparation work is done to ensure the adhesive or mortar will stick to the floor surface. Cracks and gaps can be filled with portland cement based fillers.

It cannot cure too fast. Installing tile over painted concrete adds a few extra steps to your tiling job. Mapei ultrafor plus data sheet says to use their keraply latex admix in lieu of water when going over impervious surfaces. Otherwise you do.

This surface is called a scratch coat. All paint will need to be removed before you begin installing the tile. Unfortunately the tile cannot be adhered directly to the painted surface. Mortar cannot be installed directly over painted concrete itself.