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.
Fixing cracks in concrete floor before tiling.
How to lay tile over cracked concrete cleaning the concrete.
I cut the membrane to extend at least two tile widths on both sides of the crack.
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.
For small narrow cracks that do not show signs of moisture use concrete filler which can be.
Sweep the concrete floor with a broom to remove any visible debris.
How to tile over cracked floors 1.
Cut strips of fiberglass tape designed to cover joints in cement backer board to fit over the crack.
Allow the thinset to completely dry before you seal the.
Chisel the bottom of the hole until it is flat and enlarge it slightly so the bottom of the hole is wider than.
And at only 0 8 mm thick the membrane can be used under almost any tile floor.
To repair larger holes in cement undercut the area before cleaning and filling it.
Ensuring that the cracks are completely clean before repair is key to ensuring that the repair work will hold.
Mix the thin set mortar according to package directions replacing the water with latex additive to give the mortar.