I am ready to do the shower pan pre-slope. Here is a pic of where I am at now à http://img78.imageshack.us/my.php?image=showerpanwdimensionszs3.jpg

I have been following Harry’s http://www.ontariotile.com/preslope.html

Questions are
1. What should thickness be for outer perimeter finish layer of Mud (above membrane)?

2. Inner perimeter(i.e. around drain) of Mud preslope (under membrane) - 3/8"- my problem here is that I installed the base flange according to oatey's instructions. This has the sub(or base) flange right on the sub-floor ply. So now when I add mesh a 3/8” mortar thickness will be above top of base flange. Is tapering down to top of flange for less than the 3/8” ok?

Thanks Andy

I wouldn't advise that. Another problem is that when you attach the liner, if the flange is significantly below the preslope, the liner will wrinkle quite a bit around and leading up to the flange.

From underneath, can you get to the plumbing and possibly extend the drain up 1/2" or so? If you have an inside pipe cutter you can do it from up top. You'll need a 2" union to put it back together.

Thanks for the reply Kman.

Should be no problem with the baseflange height. See this pic baseflange height . As you can see I am able to raise it up. baseflange edge is about 1/4" thick and pencil is also about 1/4" thick. I will put poly and mesh down so that they are both under the base flange and adjust height so that the top edge of the baseflange will be at 3/8".

Now for my question 1 in original post. I need to confirm the thickness the mortar should be for the outside perimeter's finished layer (i.e. mortar mix on top of liner).

I think of there being 4 thicknesses:
1. preslope(under liner) outer pereimter - 1 1/2"
2. preslope(under liner) inner (@drain) - 3/8"
3. finish layer(over liner) outer perimeter - ?
4. finish layer(over liner) inner (@drain) - 1 1/4"

My understanding is that the tiled slope should be 1/4". that is 1/4" slope for every foot for the water to drain properly. I would like to confirm from the experts what the thickness should be for #3 above.

Thanks Andy

PS. if it helps here is a pic of the entire shower subfloor and bench . It used to be a bathtub with surround.

Since the drain is not centered in the shower area, the proper slope will be harder to achieve.

Because you want the first row of tiles on the same plane, the thickness of the perimeter is dictated by the distance to the further wall from the drain. If the distance to the far wall is 4 feet for instance, then the perimeter needs to be one inch higher than the height at the drain. The problem in your case is that the distance to the left of the drain is much less than the right. The slope will be very steep at that side. Any chance the drain can be centered?

Andy
All slopes are calculated at the 1/4" min per foot of run. They can be more but never less.

I see from your photo that the drain is not centered so the furthest point, which is the corner to the right of the drain at the curb is where your run dimmension is calculated to.

The height you need at the drain is your starting point. Take your run length in inches and divide by 12. Multiply your run length times .25 Add that to your starting point height. That will be your finished perimeter height of the first layer at the farthest corner. From that point you need to maintain a level line around the perimiter. The same goes for your final layer.

The shorter distances to the drain from the wall will have a steeper slope than your long point dimension.

Also I would remove those pressure treated sill pcs and replace them with KD spruce. That pressure treated will be no end of trouble later once it starts to shrink big time and warp.

Thanks for replies guys.

Here is a pic of shower pan with dimensions

the drain location was about as good as I could get to centre because of the joist work below the area. The joists change direction right underneath this area and also sit on the walls below. I was concerned about the floor area becoming too weak.

I was hoping I could accomplish something similiar to Harrys work here

From reading in the forums here I believe I need a minimum of 1 1/4" thickness at drain. I assuming this is for proper structural strength for tiling around drain area. Is this the total thickness at drain or just the finish layer above liner.

This is what got me also wondering about the thickness for #3 outer finish layer.

Here is a pic of how I am visualizing it - Thicknesses graphic

Thanks Andy

Forget about the thickness at the perimeter. The key is to have the proper amount of slope, 1/4". You'll need that at the longest run, which is from the drain to the right front of the shower.

Using a level, you should make sure there is a roughly 1" of fall (maybe slightly less) for a 43" run. Everywhere else will have a steeper slope, since the perimeter should be at the same height all the way around. For instance, the 15" run at the front of the shower will have closer to a 3/4" slope.