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Im bidding a job to install a custom tile shower in a basement. Concrete slab foor. Block walls covered with plaster. Plaster has areas that sound hollow when tapped on. The floor already slopes nicely to an ugly floor drain. I want to have the plumber remove this drain and put in a standard two piece drain assembly. I also plan to install a CPE membrane and float a new shower floor. Standard procedure for my tile showers. Im also planning to fur out the walls and hang backboard as I feel the plaster to block bond is bad. The plumber has told the owner that this is unecessary, and now they’re questioning me. Mostly on the membrane and float. ( Marignal cost in my opinion) Im conerned about possible leakage under the curb and the possibility of mold and mildew from a continually damp subfloor. Feedback? Thanks.
Dave
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Yep, gotta' love those guys who take what they think they know to the owners instead of the guy they hired for the job. Ignorance is contagious. The membrane is an integral part--actually, it is made mandatory by bldg. depts., archs, and the industry--of a wet area installation. Without it, you will have lots of problems with water damage. Like mold & mildew, decayed plaster, tiles poppig of the wall, carpet damage in the adjoining room... oh, it's endless.
I'm right there with you thinking the plaster won't stand up to the job. There are other reasons why you don't want to have the plaster walls as part of your new shower. The plaster is probably not very flat, so you'll have a heck of a time trying to make the new tile look good. Also, plaster doesn't bond very well with portland cement based products. Besides, it is a wet area, so you better make sure you are doing it right. I believe plaster is pourous enough to transmit large quanties of water through the walls.
I was going to ask of what material the dam is made, but I realize it doesn't matter. Instead, I am interested in how you plan to finish the furred out walls at the pan membrane. Seems to me you would be carrying the backerboard right down to the finished floor HT. This goes over the pan which runs up the wall a minimum of 3" above the finished dam HT. What backerboard do you think you'll go with?
As far as your concern for leakage and mildew, if you install the pan, and install it correctly, you will not have any problems.
BTW: If your customers are still hesitant after you explain the importance of a pan membrane, just refer them to a copy of the TCA Handbook.
If they still don't go for it, run, don't walk away from this job. Impress them with the assuredness of your knowledge
*Rich:I plan on furring out the walls 3/4", with continuous "blocking" around the base extending up at least 12 inches. This should allow my membrane to extend at least 3 inches above the top of my dam. I usually use a CPE membrane from the Noble company for my pans, and attach it to the blocking with a few staples along the very top edge before floating my walls and shower floor, or installing backerboard. For this job I plan to use a 15# felt moisture barrier and Durock on the walls. I've tried Dens-Sheild and really dont like it. Seems to fall apart when it gets wet. I'll hang the Durock so it extends down over my pan material, no screws in the bottom 12 inches!! The shower floor mortar will secure the bottom of the Durock. Sound workable?BTW: My option to run is always open!Thanks....Dave
*Not my area, but a question out of curiosity...Do you advocate running the durock backer right down to the finished floor, or would it make sense to hold it off an inch or so (depends on tile size)and let the bottom course of tile bridge the backer board "gap". I'd think that cementitious backer board in contact with the floor would wick any moisture that happened to get through the seal at the floor/wall junction.Worth consideration, or an uneccessary worry?Thanks, Mongo
*Mongo, you said what I wanted to say, but couldn't put the words together. I was thinking, that once the absolute finished floor elevation is determined, the backerboard would start at some fraction of an inch--maybe even a whole inch--above that. The reason for this is exactly as Mongo had mentioned. Thanks, bro.