- Tub surround tile work: $2,000 flat.
- Kitchen backsplash tile work: $1,000 flat, labor.
- Tile floors: $3 per square foot labor, or $2 per square foot labor on jobs of 2,000 square feet or more.
Why tile cracks in Central Texas
The soil here is mostly clay. When it rains hard, the clay soaks up water and expands. When we go weeks without rain, it dries out and shrinks. That constant push and pull moves the concrete slab your house sits on. The slab does not crack evenly. It tilts, lifts, and settles by fractions of an inch. Tile is rigid. It does not bend. So when the slab moves under it, the tile has to give somewhere. That is where the crack shows up.
Most of the time the crack runs straight across the floor or follows a line from one corner of the room to another. It might appear a few months after the tile is set or it might take a full dry season. The pattern tells you what kind of movement caused it. A straight line usually means the slab cracked underneath. A stair-step crack that follows grout lines often means the whole slab is shifting. Either way, the fix is not just replacing the broken tile. The fix is giving the floor room to move.
Perimeter and field movement joints
A movement joint is a gap left in the tile that lets the floor expand and contract without crushing the tile against the wall. There are two kinds. Perimeter joints go around the edge of the room between the tile and the wall. Field joints cut the floor into smaller sections inside the room.
Most houses in Central Texas do not have enough movement joints. Builders often skip them because they are extra work. But on a slab that sits on clay, skipping them is why the tile cracks. A proper movement joint gives the floor a place to breathe.
- A perimeter joint is a 1/4 inch gap left between the tile and the base of the wall, filled with a flexible sealant instead of grout.
- A field joint is a similar gap cut through the tile every 12 to 15 feet in each direction on a large floor.
- Both joints must go through the tile, the thinset, and stop at the slab or the uncoupling membrane underneath.
- If the joint stops at the tile but the thinset is continuous, the crack will jump right across the gap.
Crack isolation membranes
A crack isolation membrane is a sheet or a liquid layer that goes between the slab and the tile. It is not a waterproofing membrane, though some products do both. Its job is to let the slab crack and move underneath without pulling the tile apart. The membrane bonds to the slab on one side and to the thinset on the other. When the slab shifts, the membrane stretches and absorbs the movement so the tile stays whole.
These membranes are not a cure for everything. If the slab is heaving more than the membrane can handle, the tile will still crack. But on most residential slabs in this area, a good crack isolation membrane buys you years of trouble free tile. The trick is putting it down right. The slab has to be clean and dry. The membrane has to be rolled or troweled to the right thickness. If it is too thin, it tears. If it is too thick, the tile will not bond. We have been using these membranes for a long time. We know what works on Central Texas clay.
Changes of plane
A change of plane is any place where the tile surface changes direction. That includes inside corners where a wall meets a floor, outside corners where a countertop meets a backsplash, and the edge of a shower curb. Every change of plane is a weak spot. The two surfaces move at different rates. The floor slab settles one way. The wall frame settles another. If the tile is grouted tight in that corner, the movement has nowhere to go. It pops the tile loose or cracks it.
The rule is simple. Every change of plane gets a movement joint. That means a gap filled with sealant, not grout. On a shower floor where the wall meets the pan, we leave a 1/8 inch gap and fill it with a flexible silicone that matches the grout color. On a floor to wall transition, we use a 1/4 inch gap and a sealant that stays soft. It is not pretty if you look close, but it keeps the tile from breaking. A lot of cracked tile jobs we see are just missing these joints.
Reading a crack pattern
When you look at a cracked tile floor, the way the crack runs tells you what happened. A single straight crack that goes across the whole room usually means the slab cracked underneath. That crack will open and close with the seasons. A stair step crack that goes from grout line to grout line means the slab is shifting as a whole block. A crack that starts at a corner of a tile and runs diagonally often means the tile was not fully supported. A pattern of many small cracks all over the floor usually means the thinset was mixed too wet or the slab had a lot of moisture.
We look at the crack pattern before we quote a repair. It tells us whether a movement joint will fix it or whether we need to pull the whole floor and start over. Sometimes a single crack can be saw cut and turned into a movement joint. Other times the damage is too wide and the tile has to come up. If you call us, we will come out and look at the floor. We will tell you what the crack pattern means and what it will take to stop it from happening again.