SFA: What's the Answer?

We do a lot of showers. We insist on doing the prep work where we use a Mapelastic waterproofing. On the ceiling and walls we like to use a high-quality, non -lump, or LFT (Large Format Tile) thinset and usually apply with a 1/2" U-notch trowel and a backparge skimcoat on the material. Have pre-cut 2x4's to support around the perimeter and edges. What is really important is that you have the proper slope on the ceiling panel which is normally sloped to the back of the shower. This prevents water droplets from accumulating on the ceiling and just hanging there. Mike Schott Onslow Stoneworks Inc.

Yes it is a skimcoat. When you make a small mix for your skimcoat, it resembles essentially a really loose, thinner-than yogurt thinset mix. What this does, other than creating a surface for the best adhesion, is that it allows the water to penetrate the substrate better than a thicker mix. So when it dries it creates even better adhesion. This coat is like a whitewash almost. As thin as a sheet of paper. No issues with airpocket. With the 1/2" trowel ("U" notched) and the LFT, it spreads beautifully. A point to remember though is that your comb needs to be in the same direction and not all swirly. Parallel lines will allow the air to escape during installation. For ceilings the direction should be in the direction of the slope and your walls should be vertical. You do not want a solid monolithic coating on the back of the material. If and when the material condensates, this gives the vapors somewhere to go. Which is also why we apply the Maplastic waterproofing to the entire area. Vibrate no, but we call it the install shimmy. When the thinset is mixed properly, it will mush right into place. Please use LFT or non-slump thinset. We use Mapei. When mixing, it is really good practice to mix thoroughly for a few minutes and let is stand for a few minutes (called slakeing) and thoroughly mix again. When you find the right water/thinset ratio for your liking, always be sure all subsequent mixes use the same ratio/slake time/mixing time.

Love panel handlers. I remember the years without them. As you know, the challenge is with fragile marbles. Now with the thin ultra-compact material it's much different and easier. We've had plenty of jobs where there was not enough room within the room to stand the material up so we had to put a horizontal seam. Customers would initially balk at that, even though they were asking to defy physics, or just remove walls which they were not willing to do. We did a good job supplementing that conversations with pictures. We explained to put a seam down low and in line with a bench, seat or some other fixture, it visually was nearly not present. Seams can be a pain but we started using large-format-tile levelers across the seam and they held those pieces just perfectly straight and gave the perfect joint space to fill. When we did mechanically anchor, we cut kerfs into the stone and epoxied stainless-steel wire into the stone and wrapped it to a fastener to the wall. We learned this from the old Italians in New York doing building cladding. Insert all of the disclaimers in the world right here!!! Unless you have the most bizarre situation, shower panels are so locked in, they don't just fall. By the time the plumbing trim, glass and other hardware is installed, it's fastened. I have had some bigger walk-ins and I suggested they put up grab bars which we said we'd install and we did.