Tenting Tile Cause and Repair

"It's important to realize not all tile tents. Your tile tented because the wrong clay was used to make your tented tile."

Tenting Tile Cause and Repair - Simple Physics

Tenting tile is a very common problem. It happened to Kevin, one of the subscribers of my FREE newsletter. Here's what he sent to me, including his photo above:

"Hi Tim, my name is Kevin and I am a long-term subscriber of your newsletter. I live in the Florida Panhandle and Friday evening while watching television I heard a loud pop/ping type of noise that sounded like a neighborhood kid had thrown a rock and hit my window.

About 30 minutes later I heard it again and did not immediately see any issues as I have a large area rug on top of my tile. Later after getting up and stepping on the rug I heard an odd grinding type noise and upon further investigation I pulled the rug back and noticed the tenting of the tiles running towards the exterior window.

My house is on a concrete slab and the tiles were in place when I purchased a home in 2002. A freeze here is rare but we did have two nights of temperatures in the upper 20s about a week prior. I was just wondering what your take on the situation."

The ceramic tile detaches from a concrete slab and creates a pressure ridge on your tile floor. My college degree is in geology and I know a thing or two about expansive clay, the clay used to make the tenting tile.

It's important to realize not all tile tents. Your tile tented because the wrong clay was used to make your tented tile.

Why Does Tile Tent?

Tenting tile is caused by expanding tile. This expansion causes a compressive force within the actual tile and a tension force between the tile and the concrete slab. Since the tile can't go down because the concrete slab is in the way, it releases the compressive force by going up. It's much like you squeezing, or compressing, an open bottle of ketchup. Squeeze it hard enough and ketchup squirts out the top of the bottle.

Why Does Tile Expand?

Ceramic tile is made from clay. Clay mineralogy is extremely complex and some clays expand and contract dramatically depending upon their moisture content. All you have to do is research expansive clay soils and see how they can cause large concrete slabs to crack and crumble. Expansive clay soils are abundant in Texas and some other USA states.

Ceramic tile made from expansive clay will be the first to tent. The underside of almost all ceramic floor tiles is unglazed and water and water vapor can enter the tile with ease. The water causes the tile to begin to expand.

Can Tenting Tile Happen After Many Years?

Tenting tile can happen at any time. It just depends on how well it was adhered to the concrete slab and what caused water or water vapor to suddenly start to move up through the concrete slab into the tile.

A well-adhered tile subject to tenting may never tent because the thinset used to bond the tile to the concrete slab is so strong it can resist the upward motion. The expansion of the tile in these instances leads to chronic crumbling and cracking of the tile grout.

How Do You Repair Tile That's Tented?

You need to remove the tented tile. Salvage as much as you can. Grind off the old thinset and seal the bottom of the tile with an oil-based matte urethane. Allow the urethane to dry for 48 hours. Seal all new tile the same way that will be used in the repair.

Install the tile back on the slab using the method you see in this thinset installation video. Do NOT SKIP the step of wetting the concrete slab before applying the thinset.

How Can Tenting Tile Be Prevented?

There are a number of ways to prevent tenting tile:

install an ASTM-1745 vapor barrier under the concrete slab
install a crack-release membrane between the tile and the slab
follow all Ceramic Tile Institute guidelines about tenting tile

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