Shower membrane

Last post I showed you the installation of the dry pack mortar bed.

This time I have the next step: the membrane.

Is it just me? I can't say "membrane" without singing ♫ Insane in the membrane* ♪
Just me? Hmm. Ok. then.

A shower pan membrane is a thick sheet (40 mil) of PVC rubber/plastic. You can buy it as a kit from the depot, and I strongly recommend that you do, if you're planning to build your own shower. More about that later.

The membrane is the main water barrier between your shower floor and the rest of your bathroom. You measure it to the size of your shower plus 6 inches up all sides - and possibly more for the part over your "curb" or shower lip. Measure twice. Membranes don't come cheap and you don't want to screw this part up. I won't lie to you: this part made me nervous.

Once you've measured and cut your membrane, you want to let it acclimate. We did this part on a really cold day (it was 18 C in the cottage) and I found myself wishing we had done it during a heat wave. The warmer temps would've allowed the creases in the membrane to soften so it would lie nice and flat.

With the membrane roughly in place, the next step was to prepare the drain. We carefully pulled back one side of the membrane to get a the drain insert. We didn't want the membrane to shift out of position at this point! I put the screws back into the drain insert and a bead of silicone caulk was applied around the top of it before the membrane was carefully lowered over top. With the membrane back in place I could feel for the screw heads, cut small Xs in the membrane, and pop the screw heads through.

Next I put the orange-y drain ring sandwich-y thinger dinger (yes, very technical terms here... try to keep up!) on the drain and twisted it slightly to catch the screws in the locking holes. I could now trace the drain opening onto the membrane with a pen. Off came the orange ring so I could trim the membrane drain hole to size with a utility knife, and then the drain ring was reinstalled and this time the screws were tightened.

With the drain in and the screws tightened, the next step was to tack down the membrane onto the walls. You want to staple it in place 1/2" from the top edge of the membrane. If you go any lower you might introduce a spot where water can escape. And that leads to mould. Ick. the paint can and inverted cereal bowl were to hold the membrane flat while the caulk set. I was worried the folds and creases would introduce leaky spots.

The corners are a little fiddly because you need to do "hospital" corners, which means the folded seam (no cutting!!!) of the membrane is a smooth line from the bottom of the corner to the top of the corner, with the folded flap neatly tucked away behind the membrane. Long staples are a good idea; like, 10 mm or longer or they don't hold the three thick layers of folded membrane in place.

The final step is to seal up the corners at the shower curb. This is where it pays to buy the pre-packaged shower liner kit from the Despot. The kit comes with two cute little dam corners that are already molded to the shape you need. You just need to apply some Oatey X-15 adhesive (use the right stuff!!) to bond the corners to the membrane, and you're done! The X-15 is narsty fume-y stuff though, so be sure to have really good ventilation when you're working if you don't have a respirator handy (really... who does?)

I don't have any photos of me gluing in the dams... probably because we were so spaced on fumes we forgot.

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*It's a song by Cypress Hill.