I have never used Kerdi-Board to waterproof a shower before but it was such an easy process. Here is how we waterproofed our shower using the Schluter Kerdi Shower System.
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How To Use The Schluter Kerdi Shower System
Securing The Kerdi-Board
Our shower was a bit more complicated because we decided to add a window as well as a shower niche which caused us to reframe some areas of the shower. Once the framing was complete we were ready to start waterproofing the shower. We used 1/2″ Kerdi-Board and secured them with the Kerdi screws and washers that come with the shower system. The screws were placed along the studs and seams of the Kerdi-Board. I used my Ryobi impact driver to secure the screws in place.
Kerdi-Board is easy to cut, you just need an exacto knife to make straight cuts. I placed a square along the line where I needed to cut and used the exacto knife to cut the section out. An easy way to locate the faucet pipes was to rub a piece of drywall on the pipe to leave a chalk mark then press the Kerdi-Board onto the pipe until it left a mark. I used a 1″ spade drill bit with my Ryobi brushless drill to cut a hole for the faucet.
Creating The Niche
We didn’t want to spend any extra money on a niche so we decided to create our own using the Kerdi-Board. For the niche measurements, we measured the back wall of the niche and subtracted half an inch from each side to account for the thickness of the sides when we folded the walls. We then took the measurement of the walls and marked them straight across the Kerdi-Board creating little squares in the corners of the board where it would be cut out. We also left a half-inch piece in the corners where the sides would be glued to each other. Once the measurements were all mapped out, we cut along each line until we were able to bend the Kerdi-Board without cutting through in order to keep it waterproof.
Waterproofing The Kerdi-Board
Once the Kerdi-Board was in place it was time to waterproof all the seams. We mixed non-modified thinset mortar with our Ryobi brushless hammer drill with a mixing paddle to a peanut butter consistency. I used a 6-inch drywall knife to add a layer of thinset mortar to the Kerdi-Board seam and placed the Kerdi waterproof strip onto the mortar then added a layer of mortar on top of the strip.
To seal the screws, I cut small pieces of the waterproofing strips and placed them on top of the screws with mortar just like the seams. You can also use Kerdi bonding compound to cover the screws as well as along the bottom of the Kerdi-Board and tub to seal any gaps.
To seal around the faucet and shower head we used a Kerdi pipe seal and used the same method as the Kerdi waterproofing strips. In order to seal the shower valve, we had to use the Kerdi bonding compound since there were no rectangular valve seals.
