Cracks and gaps can be filled with portland cement based fillers.
Tiling over concrete block wall.
For tiling over tiles in bathroom walls you ll need to set up sheets of waterproof membrane in between the concrete wall and tiles.
The safest way to approach questionable concrete is not to cover it over with cbus but to fix the concrete.
You can get this from construction or hardware stores.
Tiles come in a variety of natural and man made materials and they make durable attractive surfaces for both walls and floors.
A completed tile job is extremely heavy and requires a substrate sturdy enough to support the weight.
The key to a long lasting and attractive tile installation is proper substrate preparation.
Cinder block wall preparation first the cinder or concrete masonry unit block needs to be prepared correctly.
Installing tile over concrete walls is possible but presents some unique challenges.
Tile cannot be attached directly to painted concrete as the thin set will not adhere well to the paint.
Id board it mate quicker and you can tile straight away.
Apply commercially made filler that is made specifically for cinder or concrete blocks to create a smooth surface to which the tile can adhere.
Ventilate and dehumidify the area before during and after the installation because basement walls are usually susceptible to moisture.