The image below shows details of the sub-pan, which will be below the plastic membrane and must have the proper slope (1/4" per foot). I have seen on-line instructional videos that neglect to slope the sub-pan. This will result in bath water that never drains out of the pan, and the festering problems therein.
The beginning of this process is to project the pre-pan slope outward from the part of the three-piece shower drain that fastens to the floor, to the wall. In my case the wall was not even, so I had to make custom-tapered guides for each side that were screwed to the edges of the floor. These guides then became the basis upon which the pre-pan could be properly shaped.
Tar paper was stapled to the floor, and mesh was stapled to the tar paper. The mesh reinforces the pre-pan and the tar paper provides som de-coupling that will allow for differences of shrinkage and expansion between the pre-pan and the floor.
The next step is to pour the pan (I used quick-set cement) and to form the slope around the shower drain, as shown below.
Here, William Hackerson is forming the conical pre-pan slope using a series of pieces of wood for the slope. It was necessary to use four pieces of wood for this process to allow for changing rqadius. This process was the first concrete we had ever mixed up, and the forming went quite smoothly.
We allowed the pre-pan to harden over night before proceeding to the next step...
Here we are installing the plastic pan membrane. There was a PVC material that was available that was quite inexpensive ($27) and tough, but I went on the web and searched out health concerns of PVC and decided that it would be wiser to spend $150 more for a non-PVC membrane than many tens of thousands of dollars later in health care costs. This membrane also requires a special glue to glue it to the shower drain. This membrane is not as tough as PVC, but once it is carefully installed with the sub-pan below and the pan above, it is eternal.
Notice that William Hackerson is not wearing shoes and is sitting on a folded towel pad to protect the membrane as he is working it into place. Cold membranes are not as easy to work with as warm membranes.
We were very careful to make sure NOT to use nails in the floor (over time they can work up and possibly puncture the membrane) and also to check by hand, every part of the floor and slope-guides for any debris or projecting screw head or other hazard to the membrane. After the thorough inspection, we vacuumed the floor very well... only then did we lay out the membrane.
It is suggested to allow at least 6" extra membrane to go up the walls as a capillary safe margin. We built the shower stall with corners that allowed the corner fold to go into spaces in the corner, and keep a smooth wall.
Also very important is to put in NO NAILS through the membrane below the capillary safe margin.
Below is a photo of the drain. There were several important steps that I wasn't able to photograph because I was so involved...
Once the membrane is adjusted and in place, it is very easy to find the drain. The drain hole is cut after the membrane is situated. I used a narrow bladed knife that was quite sharp and used the inside of the drain hole as my guide. The middle ring will be bolted through the membrane to the bottom ring, and there are bolt holes that need to be located for this. I used a rounded swizzle stick to locate the bolt holes and then I used a leather punch to make the holes through the membrane. I have seen photos of professional tile people using a matte knife and cutting an "X" over each bolt hole, but that seemed very un-professional to me. I like my method better.
Also not shown is the application of the special adhesive that bonds and waterproofs the membrane to the bottom ring. The adhesive comes in a caulk-gun tube and is extruded as caulk would be, with the exception that the special adhesive is VERY VISCOUS and comes out very slowly. The tip of the caulk gun is poked under the membrane and above the bottom ring. adhesive is applied around the drain hole, and a continuous bead of adhesive is required. I chose to use a little too much rather than too little.
If you look closely at the photo, you will see, just to clockwise, near the bolt holes, at the edge of the membrane, small grooves through which water that gets past the tile and into the pan, can finally drain away. Make sure that these grooves are not blocked by glue. I took my knife and cut away small bits of membrane above each groove.
Although it was not called for, I thought it would be an improvement to improve the above-membrane porosity by adding two layers of plastic screen (not aluminum... brass would also be ok) above the membrane and below the second drain ring.
In the photo above, the caulk was applied and the second ring was bolted down and then the assembly was left overnight. The the second ring was removed and the screens were added and the second ring was bolted down, this time forever.
As a final step, I came back with a drill bit and had-twisted it to remove any bits of screen from the drain grooves.
I tested my strategy by pouring a quart of water onto the membrane, and the water flowed out, first over the second ring, and lastly through the drain grooves and screen layers under the second ring and very quickly the membrane was completely dry. Proof positive.
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Not photographed was the water test, which consisted of plugging the drain with an expanding drain plug and filling the shower floor to a depth of two inches and letting it stand over night. If the membrane is leaking it will be evident pretty quickly.
If you check it in the morning and there is no leaked water runnin on the floor, or on any surface below, and if the water is at the same depth, only then have you won and is it OK to proceed.
I won!
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Not photographed in the process below was the top ring of the three-ring drain assembly. It has threads and can be screw-adjusted to the anticipated level of the top of the mud bed + thinset + tile thickness. In the photo below, the ring has been put in place and the drain has been taped shut.
In the photo below, the tar paper has been nailed to the walls (NO NAILS BELOW THE CAPILLARY MARGIN) over the membrane margin and down to the top of the sub pan. Then the mud bed is mixed up and applied over the membrane, it is a very stiff sand mix.
The sand mix is not troweled into place, but rather pounded into place because it is so thick. Slope (1/4" per foot) most be observed as well as straightness and level of the edges. The sand mix is not quick set, so there is plenty of time to keep pounding and scraping until the proper shape and slope is achieved.
The general practice is to allow the pan to set over night before proceeding. I discovered an alternate procedure, after the fact, which is to apply the thinset and the tiles to the wet mud bed, then use small boards to check the slope and evenness of the tiles and to tape them via the board to make the floor tiles perfectly sloped and even. I wish I had done it the second way.
So after sitting overnight, it was time for tile, I used flat river stones that were glued to mesh, it was a bit tricky handling the mesh, but it worked out. Best to thinset one panel at a time.
After the thinset set up, on went the grout...
We tried a number of different grouting tools, but for the stones, pushing the grout in with the heel of the hand worked best.
Turns out that there in a 'sweet spot' during the grout drying when it is set up enough to provide strength to the tile (or stones) but is still pretty easy to rub off.
Buffing the stones with a damp cloth reveals the floor...
(to be continued...)