Questions & Answers

Project Background

• curbless shower 34.5'' by 57.5''

• originally was going with schluter pre-slope pan and switched to mud pan plan

• height difference between bottom of shower subfloor and outside subfloor is 1 1/8'' (I used 1 1/8'' plywood outside shower)

Dilemma

• trying to figure out best heights for proper slopes

I've heard the principles:

• minimum 1'' mortar under schluter drain flange (from Schluter video)

• minimum 1/4'' slope per 1'

However, I'm having trouble getting the long slope to 1/4'' per foot without raising outside floor significantly

For example, if I go 1'' drain height, 1/4'' slope over 4', then i need to find an extra inch outside the shower. Here are some alternatives:

• add 1/4 inch plywood to existing plywood to get differential of 1 3/8'' from bottom of shower subfloor to outside subfloor, with 1'' drain height, or 3/8'' slope over 4' (in sufficient 3/32''/ft. slope)

• add 1/4 inch plywood to existing plywood to get differential of 1 3/8'' from bottom of shower subfloor to outside subfloor, with 3/4'' drain height, or 5/8'' over 4' (5/32''/ft. slope, but insufficient mortar under flange)

• add 3/8 inch plywood to existing plywood to get differential of 1.5'', drain height 1', slope is .5'' over 4', or 1/8''/ft.

• add 3/8 inch plywood to existing plywood to get differential of 1.5'', drain height 3/4'', slope is 3/4'' over 4', or 3/16''/ft.

Essentially, the question is whether the minimum mortar under drain flange or shower slope are "flexible" and which is better to compromise, if either.

As to the 1/4''/ft. rule, it doesn't look like Schluter pan even abides by that DIV-22 Spec Sheet - Shower Trays.pdf (sccpublic.s3-external-1.amazonaws.com) as it only has 1% long slope, which is only 1/8''/ft.

Thanks.