For those who use a mud base shower pan with backer on the walls, do you install the backer board first so that it runs down behind the mud base? or do you install the mud base and run backer down to it? Ive seen both, whats the reasoning?
Shower- backer board and mud base
JKRasku
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For those who use a mud base shower pan with backer on the walls, do you install the backer board first so that it runs down behind the mud base? or do you install the mud base and run backer down to it? Ive seen both, whats the reasoning?
I install the backer board first, holding it about an inch off of the subfloor. The reason being, since you can't place nails lower than about six inches from the bottom (you don't want to pierce your pan liner), the deck mud helps lock in the bottom of the backer board.
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I assume you are using a vapor barrier behind the CBU (which gets penetrated when the CBU is attached to the studs), right? So then what happens to any moisture that penetrates the CBU, gets stopped by the vapor barrier and then migrates downward?
This is a fundamental issue with using CBU & a mudbed. They were never designed to work together as a system.
This is a fundamental issue with using CBU & a mudbed. They were never designed to work together as a system.
Angus, the vapor barrier extends into the shower pan by an inch or so. The moisture goes into the pan.
Ditto on what HS345 said.
I will say that if you jack the board up too high and the mud doesn't meet it leaving an inch or so gap, water will tend to collect back there unless you fill it up. It won't leak, but the water puddle will cause the grout to remain dark at the bottom of the wall forever, possible causing a mildew issue and just being generally uncool.
Ditto on what HS345 said.
I will say that if you jack the board up too high and the mud doesn't meet it leaving an inch or so gap, water will tend to collect back there unless you fill it up. It won't leak, but the water puddle will cause the grout to remain dark at the bottom of the wall forever, possible causing a mildew issue and just being generally uncool.
Yep, I use 15# felt, fastener penetrations aren't a problem, after all, it works on a roof. Although, the average annual rainfall in a shower far exceeds the average annual rainfall a roof receives.
Having said all that, I really don't build "traditional" cbu/mud base showers anymore. Surface applied, and better yet, surface bonded sheet membranes are the way to go IMHO. That way, you don't have to worry about water, or vapor penetration beyond the tile and grout.
Having said all that, I really don't build "traditional" cbu/mud base showers anymore. Surface applied, and better yet, surface bonded sheet membranes are the way to go IMHO. That way, you don't have to worry about water, or vapor penetration beyond the tile and grout.
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I glue rubber roofing to a CDX base to line tile base showers, and I bring my backer over the edge of the rubber. Then when you pour your concrete, it'll lock it in. That way if the grout cracks, the water runs to the rubber and down to the drain. It absolutely does not let water through, even if the mud in the pan cracks (which will eventually happen if the house settles significantly.)
Ummmm, you're using rubber roofing as a pan liner?
You do know grout doesn't stop water, cracked or not, don't you? :whistling
Generally, concrete is not the mud of choice for a tiled shower.
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What about epoxy grout?
Epoxy grout is much less permeable than cementitious grout, but you shouldn't rely on any grout as a waterproofing.
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:thumbsup::rockon:
what is the cost difference in materials between tradtional mud base and somthing like kerdi?Having said all that, I really don't build "traditional" cbu/mud base showers anymore. Surface applied, and better yet, surface bonded sheet membranes are the way to go IMHO. That way, you don't have to worry about water, or vapor penetration beyond the tile and grout.
I watched a video on a kerdi installation, and I have a hard time believing that it is going to hold up better and have less leakage for years to come.
The cost difference is nominal.
Why do you have a hard time believing a Kerdi shower will hold up?
You should attend a two day Kerdi workshop, that way you can give the product an honest assessment. Where are you located?
I installed my first Kerdi shower about a year ago and I am convinced that their just isn't any other method that is more cost effective and easy to work with. First one took a few extra minutes to make sure everything was right but now we can install them in no time. Its a one step project and very easy to work with.
Its a very thin cloth, with a dozen different seams at the base. maybe a pvc liner under the whole thing would make me feel more comfortable.
Kerdi is not a cloth at all. It is a polyethelene sheet, with a bonded fleece on both sides.
A PVC liner wouldn't do you any good, there would be no way to make a connection at the drain. Besides, it's not needed, the seams of Kerdi do not leak. It has been extensively tested, and I personally have installed thousands of square feet of Kerdi, I've never had a leak.
A PVC liner wouldn't do you any good, there would be no way to make a connection at the drain. Besides, it's not needed, the seams of Kerdi do not leak. It has been extensively tested, and I personally have installed thousands of square feet of Kerdi, I've never had a leak.
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Kerdi has been out since the 1980's. Try and find a single, legitimate product failure. You won't.
Sounds like you are stuck in an old school mind-set when it comes to showers. In the past, showers were designed to take in water and then deal with it. You don't have to think that way anymore. Kerdi (or other sheet membranes) keeps the moisture IN the shower. You're not relying on a barrier behind the wallboard. You're not worried about penetrating the barrier with screws or nails. You're not worried about backer board that can't be attached for the bottom 7".
As for the seams, they are addressed with a smaller version of Kerdi called Kerdi-Band and are overlapped by 2" each way minimum. Water molecules physically cannot pass through the lapped fleece. Check out Kerdi's perm rating then check out how much RedGard you have to use to achieve the same rating.
If nothing else, you need to look at the Kerdi-drain. It is the BEST Schluter invention.
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It's not my goal to get into a pissing contest, but I just want to clarify.Ummmm, you're using rubber roofing as a pan liner?
You do know grout doesn't stop water, cracked or not, don't you? :whistling
Generally, concrete is not the mud of choice for a tiled shower.
1. Rubber roofing is identical to a standard pan liner in its composition and waterproofing properties. Also I can get it in a heavier thickness--60 or even 90 mil versus 40 mil for a standard pan liner.
2. Properly sealed and maintained grout will prevent water from getting behind the tile on walls, which is what I was referring to, and I've done plenty of repair jobs where tile falls off the walls because water got through cracks and destroyed the drywall (back in the days before backerboard
.) Yes, on floors you use a solid pan liner because grout can't be trusted versus standing water.3. Sorry, I typed concrete instead of cement. Sand and portland, bla bla bla.
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