Kerdi membrane over concrete basement wall - Ceramic Tile Advice Forums

Dan Woods · 03-14-2009, 05:58 PM

I was wondering what is the best way to install the kerdi membrane over concrete basement wall. The wall is a little bumpy and not exactly even. I was wondering if I could use portland cement to install cement board directly to the wall and then install the kerdi. If not, any ideas would be greatly appreciated. Would it be better to skim coat the concrete walls to even them and then put the kerdi directly to the concrete wall?

jgleason · 03-14-2009, 06:33 PM

I think fastening furring strips to the wall and covering with a suitable substrate - drywall or CBU, then Kerdi would be better.

Dan Woods · 03-14-2009, 06:54 PM

The only problem with that is that we already set the drain and adding furring strips would throw off the measurements for the drain. 2 walls are on concrete foundation walls. Do you think it would work if it's set on to conrete?

Lazarus · 03-14-2009, 07:05 PM

If it's not too bad, you might consider "flash-patching" it with morter and going over that. Just a thought.

jgleason · 03-14-2009, 07:14 PM

Just how bumpy are we talking here? Skimming it out could work but I don't know enough to tell you exactly how that should be done.

crete51 · 03-14-2009, 07:14 PM

problen with sticken stuff to basement walls is makin sure it really bonds. forms used to pour concrete are almost alwys coated with oil to aloww easy removal when concret sets ...result nice smooth walls and a little oil residue left behind. wal needs to be cleaned ...acid etch or grind then bonding agent then skim coat then follow schluter requirements..been slingin pooky on concrete walls long time

Dan Woods · 03-14-2009, 07:38 PM

There is a concrete seam that sticks out a little. Could that be grinded down?
Other than that the walls are pretty even. The house is 50 years. I will definately use that acid to etch it. It wouldn't have to be evened to much. Thanks for the help.

cx · 03-14-2009, 07:41 PM

I'd recommend grinding the ridge and scarifying the rest of the wall, Dan, and not the acid etching.

My opinion; worth price charged.

Dan Woods · 03-14-2009, 08:08 PM

I'd be glad to but I'm not exactly sure what scarifying is.

Dan Woods · 03-14-2009, 08:19 PM

I just bought the Joh Bridge book on kerdi. I could use all the help i can get. I really appreciate all the help from his site. I use it all the time. Thanks to everyone who replys on here. Even if I didn't post the questions I still get plenty of anwers.

cx · 03-14-2009, 08:59 PM

Scarifyin' is just grindin' on it to make it clean and kinda roughed up, Dan.

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