Idea for a slip floor

[Chase Golombek]

Hello everyone. My name is Chase and i'm excited to be among the best. I hope to become one as well. I have been tiling for 5 years now, although I have only completed 8 jobs. I am a general contractor that does everything, but I want to dedicate myself to tile. So, I pick up whatever job I can to further my skills and portfolio. I will upload pictures of my work soon.

So, I do A LOT of reading. I know experience is better knowledge than books, so I hope you pros can help me with this one.
SLIP FLOOR. I had a client that tiled 400 sq ft on a manufactured home. Now, the dishwasher leaked and and caused the pressboard floor to swell. Insurance paid for an entirely new floor. His (the owner laid previous tile) tile that was set was 12x12 hard italian tile at 5/16 inch thick. was laid in grid pattern. There were no cracks!!!! Been down for 15 years. Now, here's the kicker. There was already vinyl under the floor. He put aquabar down, then screwed the 1/4inch hardiebacker to the subfloor WITHOUT thinset.

Here is my question. I'm wondering if this method acted like a slip floor. So here's my idea. Let's assume one has a floor, 3/4 in ply over joists 16 o.c. with spans adequate to accomodate the joists. Would it work to lay down aquabar or 15 lb felt, tack-hammered, then trowel 1/4x1/4 thinset under cement backer(I use durock) then screw it down. Install tile as normal.

Would this work as a slip floor to prevent cracking?

Thank you so much.

[cx]

Welcome, Chase.

Originally Posted by Chase

I know experience is better knowledge than books, so I hope you pros can help me with this one.

But only if the experience has been in using the correct methods. The books might also remind you to read and follow product manufacturers' installation instructions.

I don't know what a "slip floor" might be, but I'm guessing you intend to re-invent the wheel here and try to incorporate a crack isolation product and an uncoupling product and a CBU in a single, less expensive, combination. And you're certainly free to do that if you like, of course.

None of the CBU manufacturers, including USG, recommend or specify or even allow the use of Aquabar or similar products under their products. Each CBU manufacturer specifies the use of thinset mortar under their panels prior to fastening with mechanical fasteners. The mortar is not for bonding, but to provide a near 100 percent footprint for the CBU.

I'd recommend you follow the manufacturer's instructions if you want to use a CBU. If you want to use an uncoupling membrane, for which there is no tile industry standard, find one you like and install that per manufacturer's instructions. If you prefer a crack isolation product, for which there is an industry standard, find one of those you like and install it per its manufacturer's instructions.

I would not recommend you use the method you describe as having previously torn out just because it appeared to work successfully in the one application you witnessed, but you certainly can if you favor that and are willing to assume the risk involved with an untested method based upon anecdotal evidence.

[Chase Golombek]

Thank you CX. the thinset under the cbu does allow for a full coverage footprint, yes. I understand completely. I thought this would help if the client wanted to change tile in 20 years. I know that thinset will destroy a subfloor. By having a membrane underneath, i thought this would help with that. Since designs and fads are constantly changing.

I agree that products need to be installed to their manufacturers instructions. T

A "slip floor" is an old school term used to describe what is now an uncoupling membrane. My dad used to be a mason and he had used this method in the 80s.

[cx]

I was building houses in the 80s, Chase, so I speak some Old School, just never heard the term "slip floor" in my part of the universe.

Never been much of one for building things to make them easier to change, but we do hear folks suggest that here from time to time. Again, if you think you'd like the method you're proposing and are willing to accept the risk, use it.

[Chase Golombek]

Cleavage membrane? Is that the appropriate word?

Thank you so much for the advice.