Hello,

I have a question with regards to installing a shower base pan. I framed up the walls for the bathroom and was getting ready to install the shower base pan (photo 1). There is a small gap between the face of the studs and the edge of the shower pan along the back wall (photo 2). The gap is about 3/16" wide, tough to get a good photo of the gap, it looks small in the picture. Should i split the difference of the gap between the front and back of the shower, or should i butt it up tight to one wall, and shim the other wall? What type of shims should i get? Do they make 1.5" wide shims that are as tall as the studs, so I can nail it up the wall full height?

Next question is with regards to installing the brass drain, (you can see it in middle of pan in photo 1). The concrete dap out that I have in the basement is shown in photo 3, it was made for a tub, but I am installing shower with right hand drain. The center of the drain line is in the bottom left corner of the dap out, and you can see in photo for the orange line I traced on the edge of the concrete, that is the edge of the brass drain, so I need to notch out that little bit of concrete in the corner, about 1/4" thick around that corner. What would be the best way to do that, concrete chisel and a hammer? Don't want to mess with concrete saw if I do not have too.

Thanks in advance,
Steve

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Hi Steve

Have you confirmed that there is a PTRAP in that box out in the concrete? If not, pull back the gravel and find or install a PTRAP so it aligns with the mark you made in the concrete.

In terms of the concrete itself, you need to hammer/chisel out about an inch or so wider than you have it marked out on the concrete... no getting around that! The fact that you are chipping on an edge should make it quick and easy.

Next, check the installation instructions regarding bedding the shower pan. If you "bed" the shower pan in mortar or srtructoite perlited gypsum you will have a better job!

Bedding the shower pan will also keep it in place so that you can equalize the space around the framing using shims, bed the shower pan, level it from left to right and from front to back and then, after all has dried, simply install the cement board (if tiling). Keep the cement board up about 1/4" above the lip of the shower pan and fill that 1/4" in with silicone caulking!

Mark

No ptrap, need to install it, that's why Im laying it out now, so I can get center of drain location for setting the trap. When I try to lay the brass drain in, it almost fits in, except it sticks up about one half inch since it hits that corner of the concrete. Why do I need to go an inch wider than I have marked? If the concrete were chipped down about 1/2" deep, and 1/4" or so wide, the brass drain line would fit, and then the pvc would fit within the drain. I need to notch the concrete for the brass drain, not for the pvc. Do you want to go wider, so that no concrete is touching the brass drain, or is there some other reason?

I was going to use structolite to bed the pan.

Was going to tile, and use backer board, you want the back board to go over the flange, but stay up 1/4" from the lip, and seal that, is that what you meant?

Do I need to install a vapor barrier behind the cement board? I have heard you should, since the tile, grout, and cement board are all porous and let water vapor through.

With regards to the shims. Do you shim the entire height of the wall? If I shim around the front and back of the shower pan, do I need to shim the rest of the wall along the front & back? Otherwise my face of wall will be 1/2" thick where the drywall is, and it will be 1/2" thick cement board plus the thickness of the shim at the front and back of shower

Hey, chipping less is always a good thing! I'll let you decide that...

Vapor barrier is only required with steam shower and when your tub/shower is on an outside wall... otherwise, not needed!

You can do the cement board either way:

Shim the walls to same thickness as the base flange and then cement board and keep board off the base 1/4" as mentioned, filling that space with silicone.

Cement board to the top of the base, minus the 1/4" and then fill the space with silicone. As long as the cement board itself passes the thickness of the base flange all is good here, i.e. tile can be set properly.

Be sure to keep your tile off the base itself... leave 1/8" and then fill that space with mildew-resistant, color-matched caulk for best result!!

Both ways will work depending on what person you talk to.

Mark