I have nearly completed building my custom shower floor. The lower vinyl-type membrane has been installed. After I finish the upper sloped surface will I need to paint on a second membrane?

Hi Wezum:

Here's how I do it...

You want to prepitch the membrane to begin with. Here, make sure the floor is structurally sound and then install a layer of tar paper (15 LB felt). Float a layer of a sakrete sand/mortar from 1" at the outer edges of the shower to nothing toward the drain. Let that dry overnight and then lay another layer of tar paper over that to prevent the vinyl membrane from coming into contact with the abrasive prepitched layer of sakrete.

Install the vinyl membrane to the proper vinyl membrane shower drain and fit the corners as needed to a minimum of 6 inches above the threshold height (this is debatable). Fit the threshold and attach round patches at threshold folds/cuts. No other membrane should be needed after the vinyl membrane is installed.

Install thick floor mud (or similar shower floor product... do not use sakrete here), etc. A real pro would also wrap chicken wire for the threshold... tying into floor and then shaping and nailing off outside the vinyl pan only when all was dry.

You'll also want to be sure you:

Install a few good handfuls of gravel around the weep holes of the shower drain. It is critical that these holes do not get clogged with the mortar from the shower floor!

Install tar paper to the walls of the shower running excess past the vinyl membrane.

Install cement board to within 1/4" of the shower floor and push thinset into this space when you thinset/tape all the butt and corner joints, etc. This 1/4" space will help to prevent a WICKING effect that can cause cement boards to break down at a much increased rate. DO NOT install screws into the cement board lower than the finished height of the threshold. The threshold should be the weak spot in the system in that the shower would have water flow out of the shower via the threshold, and not any screw holes or cuts in the membrane, etc.

Use alkali-resistant screws and tape for best result.

Anyway, that's a quick bit of information... questions? Let me know...

Mark

PS: You can also use a FAST SET cement for the prepitched layer if you want to move things along, but that is usually left for more experienced installers. Finally, I have presented an abbreviated version of how I do custom shower pans with vinyl. There are many others that do it different than me... give them time to pop in and see what they think, OK? Hope it helped!