Questions about Kerdi [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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Jay Bosak
02-22-2008, 01:32 PM
Hi my name is Jay I am new to this forum and I am doing an addition onto the back of my house with a master bath. I ordered the kerdi shower system (48x 48) and I'm gonna give it a shot. I have a few questions though. Does anyone know the life expectancy of this stuff? The tray and the membrane. Will using faced batts of insulation on the exterior wall cause a problem with vapor lock? And finally is using wonder board acceptable? Has anyone here used it under the kerdi before and did they have a problem if so.? Thanks in advance for your help. Jay

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02-22-2008, 01:42 PM
welcome, Jay :wave:

a Kerdi shower will outlive the guy who builds it.

you should slice the facing of the insulation behind the shower

do yourself a big favor and use drywall - much easier to work with and there's no penalty over CBU


02-22-2008, 01:46 PM
I'm not sure I'd like to leave the stuff sitting in the sun for a long time (UV exposure), but once embedded in a wall, it should outlast you and your kids.

I'd take a razor knife and make some slits in the facing of the insulation.

Never used WOnderboard, so can't say. It really is just easier to use drywall, cheaper, too. Believe me, if you get the 2" overlap, nothing is going to get through the seams. A a class I went to, they'd taken a cardboard box, lined the inside with kerdi and thinset and had been using it as an ice bucket for iced drinks. Even with the flex of the cardboard, the thing held gallons of liquid water by the end of the day, and the cardboard was perfectly dry all over. They'd been using it for months. If you take a square, roll it into a cone, even though there's no overlap at the point, fill it with water, it won't leak out. The stuff just repels the water.

Drywall is plenty strong enough once you have the two layers of thinset, the Kerdi, and a layer of rigid tile. You'll have fewer seams, too.

02-22-2008, 01:51 PM
Jay, welcome to the forum.

And what Art and Jim said. :)

Jay Bosak
02-22-2008, 03:32 PM
Thanks for the help I appreciate it, I'll keep you posted on my progress.