Clean the concrete surface and apply a thinset compound to all of the low areas until the surface of the concrete pad is smooth and level.
Fixing cracks in concrete floor before tiling.
How to tile over cracked floors 1.
Mix the thin set mortar according to package directions replacing the water with latex additive to give the mortar.
To repair larger holes in cement undercut the area before cleaning and filling it.
Cut strips of fiberglass tape designed to cover joints in cement backer board to fit over the crack.
Using a scraper and a wire.
Ensuring that the cracks are completely clean before repair is key to ensuring that the repair work will hold.
Use a chisel and hammer to undercut the crack meaning that you cut it into an inverted v shape so that the base is at least 1 inch wider than the top of the crack which will ensure that the patching compound has a solid place to flow and bond establishing a stronger hold.
And at only 0 8 mm thick the membrane can be used under almost any tile floor.
The membrane which is bonded to the slab with the same latex modified thinset that i use for installing the tile absorbs any additional movement in the concrete.
How to lay tile over cracked concrete cleaning the concrete.
Force the thin set into the crack.
Allow the thinset to completely dry before you seal the.
I cut the membrane to extend at least two tile widths on both sides of the crack.