Using a scraper and a wire.
Tile on concrete slab with cracks.
Concrete is similar enough to tile in terms of expansion and it doesn t flex so you don t need crack protection just use a decent polymer modified mortar.
In some cases i ve seen cracks that are almost 1 4 in.
If you watch them tile a commercial center or office building which are always concrete floors you never see them use crack prevention.
Applying tile in these situations is really quite simple.
Concrete can support a lot of weight in compression but is weak in tension.
If the water soaks in you re good to go.
For small narrow cracks that do not show signs of moisture use concrete filler which can be.
But larger cracks especially those that are higher on one side than the other may telegraph through the tile and cause it to crack.
If you are placing tile on the slab it s important the control joint line up with a control joint in the tile easier said than done.
Instead of a crack transferring from the concrete to the tile the crack isolation membrane absorbs the crack energy and spreads it over a large area preventing telegraphing through the tile.
Before you install any flooring material over a concrete slab it is important to inspect the slab for defects.
Cracks in a concrete slab are a problem that i run into frequently.
Let the primer dry and then apply the membrane photos 3 and 4.
In some cases the crack may instead occur in the grout joint.
With the cracks patched apply a latex modified crack resistant thin set.
Cracks are nothing out of the ordinary.
Dips bulges and cracks occur frequently as concrete cures and ages.
Small cracks caused by shrinkage usually do not present a problem.
Cracks in concrete floors or slabs occur in poured concrete slabs may be found both in basement and in slab on grade or patio home construction and have a variety of causes and cures that we discuss here as we explain how to repair cracked concrete floors and as we describe slab on grade construction or patio home construction cracks and as we review the diagnosis of cracks in ceramic tile over concrete slab floors.
Cut the membrane so it s 1 1 2 times the width of your tiles.
Then prime the concrete see photo 2 with the recommended solution consult the membrane manufacturer s literature.
Tom meehan a tile installer and owner of cape cod tileworks in harwich massachusetts replies.
The drying would cause shrinkage or compaction of the dirt possibly enough to create a void under the slab followed by the slab cracking and settling over the area of the void.
How to lay tile over cracked concrete cleaning the concrete.
To find out if a concrete slab is clean pour a little water on it in spots.
So random cracking might be a better approach for tile.
If tile were set on.
