How to Build a Mud Set Shower Pan

Following the proper steps when building a shower pan is critical to avoid expensive leaks down the line. The following guideline is an industry best practice.

Difficulty: Moderately Challenging

Instructions

Things You'll Need:

• Skillsaw
• Drill
• Hammer
• 2x4 Lumber
• 2x10 Lumber
• 3/4" Exterior Plywood
• 1 1/2" Stainless Steel Screws

1. 
    

   Assuming you are starting with a bare plywood subfloor, install wooden blocking to create your curb at the edge of the shower pan. The curb is the elevated threshold directly beneath the shower door location. This curb retains shower water from overflowing into your bathroom. This is clearly shown in the picture above.

2. Install the curb by stacking 2x4 cuts of wood on top of one another and nailing them together. You want the height of your curb to be roughly 6 1/2" above the top of shower drain. This will provide for the typical 8" high finished curb once tile is installed.

3. Install 2x10 blocking all the way around the bottom perimeter of the shower. Screw or nail the 2x10's between the wall studs.

4. This step is critical: frame in the slope of your shower pan. Do this by measuring from the edge of the shower pan to an 1 1/4" below the top of the drain, leaving room for mortar and tile. The slope needs to be 1/4" per foot. "Rip" pieces of 2x4 using the Skillsaw to create wedge like strips in the shape of the slope. Screw these into the plywood subfloor with stainless steel screws.

5. Cut pieces of plywood to install over the 2x4 rips. Be sure your pieces of plywood fit together well and without any large gaps at the seams. Fasten the plywood to the rips with stainless steel screws.

6. 
    

   Call a roofing company and have them "hot mop" the shower pan. This is the only sure method of waterproofing shower pans. You may be able to use a membrane system, but sheet membranes can tear during mortar install and tar does not have that vulnerability. Further, some municipalities only accept a hot mopped shower pan, so check with the building department.

7. Once the hot mop is complete perform a 24 hour water test. Plug the drain and fill the shower pan with water to just below the top of the curb. You'll know right away if there is a real problem, but it will take up to 24 hours for small leak to show itself. If you have a leak, just call the roofing company to return and get the job done right.

8. Float the shower pan with mortar. This is fairly easy as the slope is framed in and all you have to do is keep an even mortar bed from the drain to the shower walls and curb.

[tileman]

on 7/22/2009 I disagree with this author......again. That is no way to build a shower. I have seen some other videos & can only say the methods are amateurish at best.

I recommend either a standard membrane method with pre-slope of course, or for a totally waterproof shower I would go with a Kerdi membrane & drain system.

The hot-tar method is a west-coast thing and works well. There are several other steps however that are not professional.

Jaz @ Tile 4 You Inc.