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04-12-2011, 12:08 AM
I have finally converted to Kerdi for my house and bathroom renovation. I have downloaded the e book and hanging the Kerdi on the walls seems easy, it's the soap / window area that has given me a little bit of fuss.

my observations -

inside corners with respect to the main piece cut in to fit the soap niche stay put, outside edges seem to want to creep back a bit forcing me to pull up the piece and add more thinset ( Laticrete 317 ) to re-secure and then re flatten with my drywall knife the piece down to minimize build up and bulge.

I am amazed how tough Kerdi is and how well secured the fleece is , as I was really pushing down with my drywall knife to ensure embedding into the thinset and to squeegee excess thinset out. I also did not like how quickly the thinset set up over the small bit and pieces of Hardibacker inside the soap niche and window area, the rest was 5/8" drywall, over that it laid down nicely.

As I left the bathroom tonight, I noticed small bubbles right on the outside corners. should i pull it apart tomorrow or make a small incision and fill it with Kerdi fix? or do you think it will progressively delaminate over time?

Also with the build up, especially over the soap niche area, how much thinset can you layer up to feather out the build up over the Kerdi, or is Kerdi meant to be a used in conjunction with a appropriate thinset layer ( respective to tile being set, in my case 10 x 14 ceramic tiles ).

Alfredo Alvarado
So Cal

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04-12-2011, 12:49 AM
Hi Alfredo,

Generally, here's what I'd do. In regard to your bubble, - depends on how big it is. If its like the size of a quarter, I'd just slit it and ooze some Kfix in there, squish it around underneith then a bit of Kfix over the small slit and your good.

If it is bigger or takes a bigger slit, then I'd just consider cutting it out and putting a Kerdi-band patch over it. Remember 2" overlap of any opening.

Specifically on your "right outside corners." . . . I'd have to see where your talking about the problem. Pic would be nice (with a fancy red arrow pointing to the spot). But in lieu of that maybe a more detailed description. i.e. "its on the curb, right on the fold at the top of the curb to the front of the curb, etc.

Main thing in my mind - if it doesn't suck into place when its first set and wet, leaving a bit of puckering, then when its dry it will be a floppy air-pocket with no attachment. So it needs to be attended to.

Ways to avoid that in the future (if there is a future Kerdi project) - pre-fold and crease the Kerdi so its formed to the curb (or whatever) before you set it in place. And secondly, you can stretch it into place and if it wants to slink back and pucker, you can use a few push-pins, nails or whatever to hold it in place. When I do that I always take my sharpie and circle the penetration right then, so that when I come back the following day I can pull all the pins, etc. and K-fix any pin holes. Usually not a big concern anyway outside the curb, but what the hey. The reason we're using Kerdi means were more conservative to begin with, so why stop outside the curb.

Good luck

04-12-2011, 04:33 AM
For outside corners, round over the substrate to about a 1/4" radius. All sheet membranes do not like making sharp corners, but seem happy with slightly rounded ones.