Op Editorials
Cementitious Water Damping Products Help Prevent Failures
Let’s talk about tile and why it’s important to install a flexible cementitious water dampening product behind it. Concrete cracks including shotcrete whether dry or wet. Dry is less likely to crack because of the low water to cement ratio but it will at some point crack. Most cracks are due to shrinkage because as concrete cures it expels moisture and changes volume and gets smaller and something has to give. Shrinkage cracks in pools are not an issue.
The American Shotcrete Association addresses shrinkage cracks in pools and the proper way to fix them. There are damp proofing manufacturers that have specific protocols to fix them. When it comes to tile especially glass tile there is a reason why manufacturers require a cementitious flexible membrane.
After waiting the 28 day cure time before applying tile the concrete is still curing and changing volume. In addition to allowing the tile to flex a membrane allows flexibility so if you incur a crack it will not affect the tile. Take for example the pool in the pictures attached to this post. I was called out to look at water dampening this pool because the owner felt the shrinkage cracks in her negative edge wall was a signal the pool was failing and needed extra help.
This was the least of her problems. Besides the abhorrent shotcrete job and hydraulics the tile was popping off on the edge wall right where the shrinkage cracks were due to the tile installer not installing a membrane to allow the tile to flex as the shell was losing volume. Concrete can take decades to fully cure which is even more reason to install products that will make your tile installation counteract the curing process. As the pool sat and cured with the tile installed and shrinkage cracks appeared it popped off the tile and led to a failure of the tile.
It’s important to follow TCNA protocols and those from the manufacturer.
Grant Smith
