Can tar paper be used as underlayment for tiling on a concrete slab, and what affordable adhesive would be best for this project?
Asked by Addison Jackson 
3 months ago
Last Updated: September 29, 2024
Hey everyone,
I’m about to tackle tile work in my guest bathroom for the first time, and it’s on a concrete slab.
I have a few questions.
Would tar paper work as a good underlayment for the tile, and if so, what adhesive should I use to stick it to the concrete?
I’m also trying to keep costs down for this project. Thanks in advance!
Skip the underlayment and install the tile directly on the slab. Make sure to use a high-quality thinset mortar that needs to be mixed
If I place the tile directly on the concrete, wouldn’t the tile or grout crack if the concrete cracks over time?
New text: If I put the tile directly on the concrete, would the tile or grout crack if the concrete cracks over time?
Do you happen to know how old this concrete is?
1979
If the membrane is not cracked or shifting currently, it is highly unlikely to do so unless there is an earthquake. Unless you are working in a wet area and require water containment (use schluter), underlayment is not needed.
When it comes to attaching tile to concrete, there are three methods you can use. The best one is installing the tile with an uncoupling membrane in between. Another option is placing a CBU or cement board on the concrete before tiling. The least recommended method is attaching the tile directly to the concrete.
Hey Robin, do I have to use adhesive spray to make the membrane stick to the ground? Or does it just float freely?
Hey, who was asking about that product? Ditra, right?
Just make sure to stick to the manufacturer’s instructions
https://www.schluter.com/schluter-us/en_US/Membranes/Uncoupling-(DITRA)/Schluter®-DITRA-&-DITRA-XL/p/DITRA?language=en_US
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It’s applied with unmodified thinset by an anonymous participant.
Have you thought about using an uncoupling membrane?
Do I have to use adhesive to make the membrane stick to the floor? Or is it supposed to float?
Participant using schluter style should apply thinset.
It’s just a bathroom, so you don’t need to spend a fortune on an uncoupling membrane. For instance, two decades ago I tiled a basement laundry room with inexpensive tile on a concrete slab that had small cracks. I applied tile backboard tape over the cracks before tiling, and I haven’t had any cracks show through the tile since then.
You have the choice to tile directly onto concrete or utilize a membrane such as Ditra.
Why use tar paper? I’ve always just used thinset and started laying tiles.