Building a Shower Floor from Scratch - In a Tiny House on Wheels - Light Weight Design Challenges 

Very nice work. I was glad to see you used the Kerdi membrane. When doing an RV don't use heavy Hardiebacker board, use Kerdiboard. It is lightweight and waterproof. Hardie by contrast crumbles with water contact. Wrong choice but the membrane saved it. The key thing about RV tiling vs house: 1. Use Polymer in the Thinset Mortar instead of water. 2. Use Polymer in the Grout instead of water. MAPEI is an Italian tiling company and Lowes carries their product. They make a very good Thinset Mortar and a Polymer which work together. They also make Grout and Grout Maximizer (polymer for grout). When you use these polymers instead of water, the rubber compounds make the thinset and grout more flexible so they won't crack and pop tiles under the constant vibration of a moving vehicle. They grab better too. The Grout Maximizer eliminates the need for sealant on grout lines, as it is built in. How nice! Lack of sealant means water penetration. Schluter makes a waterproof Kerdi membrane which you used. Schluter makes Kerdi board, a backerboard for tiling but very different. It is a type of dense, resilient foam encased in the Kerdi membrane. The advantage - much lighter than normal cement board, completely waterproof, and also provides cushioning for tile, so there is some springiness in the substrate and tiles withstand van movement better. A far superior backerboard. No, Wedi is not the same but similar concept. Kerdi is the best board and the priciest! Kerdi board does not disintegrate if water hits it all the way through. Most cement boards disintegrate with any water. Schluter makes a tile floating substrate called Ditra which resembles a waffle. It is a bit thick. But you would use it like a backer board and fill with thinset like butter in a waffle. The advantage is, that the tiles float on the surface and breakage does not happen. Good for larger tiles in an RV. Just so you know they exist. A pricey German line but where it counts, it should be used. Don't take shortcuts on sleeping bags and tents when climbing Mt Everest and similarly get the most leakproof thing when making a shower stall regardless of cost. When a job is done well, it lasts forever. My 1997 RV has undercoating that is still in excellent shape, amazing! They did a first class job on that. There is another great product I found: Innovera by Palram at Home Depot. These are vinyl tiles that clicklock into place on each other. They also sell a vertical strip for inside two corners and you can finish off with aluminum tile borders on outside. This comes in a few basic finishes and one of them is Carrera Marble. Lovely! You stick the tiles on - they are very light. Caulk between them if used in a shower stall. Only for walls not floor. Meant for home bathrooms and an easy remodel over existing tiles. I find them excellent for an RV bathroom. Low profile not thick, lightweight foam core with vinyl overlay, waterproof, easy to apply, easy to cut, done very fast. Stick with construction adhesive to the waterproofed wood walls, and caulk in between. These will match your marble tile on floor.

I'm so glad you didn't put nail holes in the kerdi .

The kerdi material is waterproof definitely, the problem is in the seams if you have to cut it. As in your case you could have done a closet fold in the corner similar to the rubber liner method and it would be fine. Tile coach channel uses a liquid membrane on top which I recommend as well so you know the cuts and glued parts are waterproof.

I like it, thats probably close to the way I would do it in an rv. You really do good work and its nice to see there are people out there that still take pride in their work, it seems all but lost nowadays. Everyone wants production over workmanship, quantity over quality. Keep up the great work sir.

Genius ! I hate schluter kerdi but I recently did same exact thing fir a curbless shower, the membrane is definitely waterproof, although I was still fixated on using a liquid topical membrane in all the seams and the entire area for that matter

Thank you for making this. I will definitely be trying this at home, won't blame you if I eff it up though

such a beautiful floor. Such bland walls I ve never build a shower. But I really want to. I really enjoy listening and watching here.

Looks to me like you did a awesome job!!! I can't see any place that will leak or give any problems.

I think I'll try that at home

Very nice shower floor! Looks strong, and waterproof. I'm sure it'll give them years of service. I am curious how you worked out the angle cuts at the ends of the 2x2's. The way I think I'd have tackled it, would be to set a speed square inside the frame on the floor on its flange side, the 90 degree side butted up against the frame, and the flange side pointed toward the drain. Then take a straight 2x2, slightly longer than what you'll need, and put the bottom corner on the edge of the wooden block around the drain where you want the top corner of the 2x2 to end up (may need to rest it temporarily on another 2x2, so the bottom corner is exactly at the edge of the block), and rest the other end on the frame, then draw a pencil mark on the side of 2x2 along the edge of the speed square, then move the speed square to the other side of the 2x2 and draw another line on that side. This gives the 'miter angle' (lines on the sides from top surface to bottom surface) to cut the 2x2 at the frame end, plus its length. Move the speed square to butt up against the block around the drain and draw similar vertical lines on the drain end, from the bottom corners up on each side, to define the sliver to cut (or sand) off of that end. Then to find the 'bevel angle' (lines on bottoms from left surface to right surface of the 2x2), draw a pencil mark on the bottom of the 2x2 from below, along the edge of the frame. Do the same on the drain end, referencing along the edge of the block around the drain. These procedures should end up giving accurate pencil lines on the sides and bottoms of all the 2x2's, on both ends, and then just cut with the saw following all 3 of these lines. Oh, and since the drain is surrounded by a block made from 2 pieces of 3/4" plywood (1 1/2"), and the 2x2 is 1 1/2" but at a slight angle, the surface of the 2x2 meeting up to the block around the drain is going to be slightly taller than 1 1/2" (which would also put the angles a bit out of whack), and so the bottom of that end of the 2x2 will probably need a bit sanded off to get its top surface to flush up to the top surface of the block around the drain. But as I say, I'm curious how you did do it, since yours looks very neat with tight joints.

I wouldve definitely used a foam shower system. Wedi makes a 3/4 inch foam pan that can create a curbless entry. All you have to do it recess 3/4 inch ply flush with joists. With wedi, its completely waterproof. There's fewer parts to create the shower assembly and it's a ton more straightforward. Good thinking though!

Things will flex a bit being in an RV, but that Kerdi should prevent any issues. You could also have used a liquid roll on membrane like redgard.

Really interesting... I'm here because I'm looking to do something similar in a cargo trailer conversion. So you just put up waterproof sheathing on the walls and are relying on the aggressive slope of the drain to direct water away from the bottom corners of the walls? What if there is a clog and water builds up in the pan? what if they like to kick water in the corners?

Hi. Are you available to build one? It's for a new van conversion so I need it lightweight. I do NOT want to use foam like someone suggested LOL, but mounted to the van properly like you did in this video. I plan to use 80/20 for the wall skeleton as it's super strong and you can add bolts anywhere needed. Please let me know if you're available for hire later this year or early next. Thanks

Should have went with the schulter drain. Best 100 bucks i ever spent.

So Long As It Remains Rigid. You should get longevity out of that. Longevity being 15 years maybe

You do know they make foam pans right lol

If the Membrane does not tare, should last.

That’s never been lightweight in the slightest 😂