Schluter®-KERDI - Bonded waterproofing and vapor-retardant membrane. The Kerdi-drain has a bonding surface that allows the membrane to be attached at the upper surface of the floor mortar instead of underneath it. The tiles are than cemented directly to the membrane, which goes from the drain across the floor and all the way up the walls to the height of the shower head in one continuous run. The waterproof membrane isn't a substitute for the substrate. It is a topical waterproofing layer that is put over the substrate to keep water from getting to the wood frame and nails. My understanding is that Schluter-Kerdi, being a sheet topical membrane, recommends just going with regular drywall instead of cement board but you can certainly use cement board as the substrate.

First Kerdi can be installed on drywall or cement board. However if installed on drywall it is only protecting one side. The back side of the drywall fails and it is just as bad or worse than if it had an issue on the tile side. All shower/tub areas should have concrete board (I prefer hardiboard). Whether or not you need a Kerdi membrane is a factor of use.

In normal residential use I wouldn't worry about it. Backerboard plus a waterproofing membrane like Redgard is all that is needed for tub surrounds with thinset then tile. Kerdi really offers very little advantage over hardiboard plus membrane. There's a really great manual (with diagrams) that makes this all easier to understand. You absolutely need to include some sort of substrate (cement board, green board, regular drywall) with the Schluter-Kerdi waterproofing kit. The waterproof membrane isn't a substitute for the substrate. It is a topical waterproofing layer that is put over the substrate to keep water from getting to the wood frame and nails.

My understanding is that Schluter-Kerdi, being a sheet topical membrane, recommends just going with regular drywall instead of cement board but you can certainly use cement board as the substrate. It doesn't matter but you absolutely need to use both a substrate and a waterproofing membrane. The site is called floorelf.com. The manual can be found here: I would say unless you are experienced in working with Schluter-Kerdi waterproofing membrane kit, then I would say work with an easier waterproofing approach, either liquid waterproofing or a combination of liquid and traditional waterproofing (plastic covering the wood frame). Here is a video off the Schluter-Kerdi website that describes how to apply the waterproof membrane on top of the substrate (gypsum board in this case). Welcome to the site. #1 - Backer board has nothing to do with HD or any other big box.

Mike Holmes uses backer on his show. Actually if you watch any pros work (not on crappy shows) on TV you will see them use backer board 99% of the time. #2 - Your suggestion has plenty of merit though. Download Mapa Europa Igo 8.3 here. A mortar wall is better and can be customized easier.

#3 This is a DIY site. We don't expect people to master this and in fact I know maybe two guys in my area (live in big city) that could do this. #4 You could be adding a good 1000 pounds to your install too. – Jun 30 '16 at 3:25 •.

• Watertight and free from mold, this ceramic tile shower system is for you. Bridge (April 2004) Yep, I’m a mud man. I’ve been building showers and all sorts of things out of cement mortar for over three decades now. Nothing like mud. It’s so permanent.

I’ve run onto another method for building showers, though, that rivals the mud method. I like it so much, in fact, that I’ve been employing it with ever increasing frequency. Most showers I build nowadays are built using Schluter Kerdi, a membrane made by my friends at, the folks who subsidized the cost of producing my book,. Kerdi Installed Over Sheetrock Kerdi membrane being installed over sheetrock shower walls. The biggest single difference between a Kerdi shower and one built by other means is that it is completely waterproof. Moisture never has a chance to get into what’s underneath the tile and grout.