Kerdi layout question [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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04-06-2013, 11:39 AM
Hi - been a long time since I last posted. I've done a few tub surrounds using the Kerdi membrane with great success. Now I'm getting ready to do a full shower, 48 x 48 with walls on 3 sides. I have the Schluter kit on hand and am second guessing myself on how to best use the Kerdi that came with the kit. It is 108 sq. ft. and it seems they have probably calculated it down to the last inch. The pan will take 16 sq. ft. leaving me with 92 sq.ft. Then I have to allow enough for the curb which is 6" high, 4" wide and 48" long. I am hoping to take the membrane up to 78" or 80" on the walls. The membrane on the roll is right at 39.5 inches wide.

Has anyone done a layout like this? Any tips on the best way to cut the membrane? I am hoping to avoid having a bunch of thin strips left to try and piece in any gaps. I will be using the Kerdi Band for all inside corners and around the pan.

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04-06-2013, 11:53 AM
108 sq. ft. is 108 sq. ft..

you have 78-79 sq.ft. on your walls and 16 sq.ft. on your floor = 95 sq.ft

your curb isnt going to use 12-13 sq.ft. on it.

you also have the Kerdi band in your corners and it can be
used on both edges of the curb,

you'll be fine.

I pre-cut all my Kerdi prior to installation.


04-06-2013, 12:00 PM
Hi. You will have plenty of material there. I believe that is a 33' long roll at about 39" wide, right? Think of the walls first; it you peel off 48" and another 48" you can do one wall to a height of 76" (39 plus 39 less 2" overlap). That's only 8ft used so far. So 24 ft will do all three walls. (Actually if your wall width is 48", you will probably cut the kerdi at 47 to 47-1/2 so it fits nice, the kerdi band will cover the 1/4 to 1/2" on each side margin.)
You still have 9ft length by 39" wide to do the floor and curb. If you want to get higher than 76" you can add strips at the top from the leftovers.
That's the way I would do it; love to hear from others if they have a different approach!

As an aside, I do NOT worry too much about lapping the kerdi the way you would lap flashing. It's counterintuitive, but really it does not matter. It just depends on where you want to apply your kerdi and kerdi-bands first.

04-06-2013, 02:47 PM
FWIW, you can install the Kerdi-band first, then install the sheets - as long as things overlap at least 2", the seam will be fine. I think this hides the transitions better. Most inspectors want to see the waterproofing at least up to the height of the showerhead...any higher is your call.

04-06-2013, 04:49 PM
Seems like it should be enough. Butt your seams and Kerdi-band em to help maximize your roll of Kerdi

04-06-2013, 04:54 PM
.....if there is enough kerdi band in your kit

04-06-2013, 05:56 PM
I dont think the kerdi band comes in the kit.

I dont use the shower tray kits, but this is on the website.

In order to complete Shower installation you will need
following Schluter products:

Schluter KERDI-BAND KEBA 100/125/5M Waterproof
Strip Membrane - 5" x 16'5".

04-06-2013, 07:38 PM
Thanks everyone - some good tips to consider. Yes, the shower kit does not come with the band.

04-06-2013, 07:55 PM
I have just done a 48x48" Schluter Shower Kit (Canadian version maybe) and it came with Kerdi Band which I hardly used. My shower is 54x34x8' high.
There is plenty of material there; you will have no issues.

04-06-2013, 10:36 PM

I did find on the Schluter site the kit showing it does have it.maybe the old kits didnt have it? :shrug:


is an all-inclusive package containing each of the integrated family of components required to create
a watertight shower assembly without a mortar bed. This includes a prefabricated tray, which is available in different sizes, curb, KERDI
membrane, KERDI-BAND, KERDI-KERECK-F pre-formed corners, and the KERDI-DRAIN.

04-07-2013, 09:32 AM
kits i get in ohio have plenty of band in them. i overlap the sheets so i dont use much. prolly have 800 ft. in garage.

Bodie Powers
04-07-2013, 10:12 AM
108 sq feet for that shower is tight but doable.

You're starting with 33 lineal feet.

To cover the three 48" wide walls plus (I assume) two 6" jambs to a height of 78" will consume 26 lineal feet.

That leaves 7 lineal feet for the floor/curb.

You'll use 4.75 lin. feet for a 39" wide strip across the floor to the outside edge of the curb top.

That leaves 2.25 lineal feel to cover the remaining floor/curb section that is 9" wide by 4.75 feet. This will require some patchwork.

Yes, 108 sq feet is enough....but just enough. Given the exorbitant price they charge for that kit you'd think they could have thrown in an extra 3 lineal feet to avoid having to do the patch (and to give the installer a bit extra for niches). :wtf:??

04-07-2013, 08:46 PM
Thanks Bodie. I am using a Noble niche so it will not need to be lined.

04-08-2013, 06:02 AM
Thanks everyone - some good tips to consider. Yes, the shower kit does not come with the band.

My DOES come with the band, it was inside the box containing the drain kit.