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I’ve been setting tile for a while and I usually build my shower pan out of mortar just like Mike Byrne does in his book. Most guys seem to do the same. I first float a thin layer of mortar so that the shower pan liner has a slope to the drain and then I float a thicker mortar bed with wire screen built in for strenght. The curb is built around a verticle 2×6 so that the vinyl liner has something to go up and over. Here’s the question, one of the oldest tile setters in town says that this isn’t a good technique. He says he has torn up about a 100 shower pans (I believe this could be close to the truth)and that he has found that the 2×6 will usually be rotted and that the mortar will sometimes be broken up or otherwise not intact. He says that the only way to build a shower pan is the same general method but to use concrete and not to use any wood in the shower curb. He does the same thing with sloping the shower pan, etc. What do you think? Is there any reason not to trust mortar for this application? Have you found rotten wood cores in the curb. He makes it clear that he is building these things to last a lifetime, not just 5 or 10years. Thanks for the info.
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I found most of the tear-outs I have done had the same conditions. But all of the tear-outs also had lead pans rather than vinyl. I think if the vinyl is laid correctly, you will have no rot. Nontheless, I started using plastic or vinyl lumber a couple of years ago after scounging it off a fence job. Since then I've put the word out to fellow deck and fence builders that I'll take all the 3' plus scraps they have. Have not had to buy a stick. Anything to avoid concrete!!
*I do all my pans in concrete including the curb. I run the membrane up the wall at least 1 foot. I set the floor tile and curb with Hydroment Ultra-set and have not had a problem yet.Steven "knocking on wood" Blumenthal
*Paul:My guess is all the pans the "old man" has torn out did not use dam corners in combination with the pan membrane. It only takes a pin hole, and this is the most likely place to get a leak.Dave
*The real issue is rotted wood curbing, which has little to do with the type of pan mud you use. Using concrete, however, defeats the "system" that is the shower pan. Pan mud is porous and is designed to allow excess water to pass through it to the pan liner, or membrane. If the substrate is pre-sloped, this excess water should run to the weep holes in the flange of the drain collar/strainer, helping to keep the pan dry. Concrete is made with a Type S portland cement and aggregate that may be considered water-tight when dry. I would also imagine that it's more difficult to float than a dry-pack bed. The way to prevent rotted lumber under the curb is to use PT lumber and avoid making nail holes in the membrane that rides over the curb. Also, ensure that the corners of the curb at the base of the shower entry door are sealed using a poly-vinyl, pre-formed dam.
where does one purchase poly vinyl pre formed corner dams.
for mortar bed shower pans
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I've been setting tile for a while and I usually build my shower pan out of mortar just like Mike Byrne does in his book. Most guys seem to do the same. I first float a thin layer of mortar so that the shower pan liner has a slope to the drain and then I float a thicker mortar bed with wire screen built in for strenght. The curb is built around a verticle 2x6 so that the vinyl liner has something to go up and over. Here's the question, one of the oldest tile setters in town says that this isn't a good technique. He says he has torn up about a 100 shower pans (I believe this could be close to the truth)and that he has found that the 2x6 will usually be rotted and that the mortar will sometimes be broken up or otherwise not intact. He says that the only way to build a shower pan is the same general method but to use concrete and not to use any wood in the shower curb. He does the same thing with sloping the shower pan, etc. What do you think? Is there any reason not to trust mortar for this application? Have you found rotten wood cores in the curb. He makes it clear that he is building these things to last a lifetime, not just 5 or 10years. Thanks for the info.