Ceramic Tile Advice Forums - John Bridge Ceramic Tile

Welcome to John Bridge / Tile Your World, the friendliest DIY Forum on the Internet

Advertiser Directory
JohnBridge.com Home
Buy John Bridge's Books

Go Back   Ceramic Tile Advice Forums - John Bridge Ceramic Tile > Tile & Stone Forums > Tile Forum/Advice Board


Thread Tools Search this Thread
Unread 09-20-2021, 04:42 PM   #1
Registered User
Join Date: Sep 2021
Posts: 2
Drain height, subfloor preslope question

Hi everyone, I apologize for the redundancy of this question but this is my first shower floor and I'm having some trouble communicating with my plumber.

We took out a shower/tub combo and plan to build a shower; the plumber centered the drain for us but left the drain base level with the subfloor. I have reinforced the subfloor with 1/2 in plywood (so it looks a little different from the photos) but I want him to raise the drain base so it's another 1/2 in off the subfloor and still level. This is so my pre-slope can be 1/2 in thick minimum at the drain base.

Everything I have read, every diagram I have seen on JohnBridge and everyone I have consulted seems to be in agreement with this, but the plumber is having a lot of trouble understanding why I am requesting the drain base be raised. He said everyone else he works with just places a liner right up to the drain base. I really want to do this right and have a solid foundation upon which the shower is fabricated. Looking for more reassurance that this 1/2 in elevation is necessary in order to “pour” a preslope with an adequate minimum thickness.

Thanks in advance for keeping me pointed in the right direction.

Attached Images
jllinny is offline   Reply With Quote
Sponsored Links
Unread 09-20-2021, 05:45 PM   #2
Moderator emeritus
cx's Avatar
Join Date: Jul 2001
Location: Boerne, Texas
Posts: 93,820
Welcome, Jen.

Your plumber is, unfortunately, in the majority of plumbers who don't know that the shower pre-slope and liner are part of the drain system and are their responsibility. Also unfortunate, is the fact that there is no actual requirement for how the pre-slope must be constructed. The requirement is that the waterproof liner must slope a minimum of 1/4" per foot to the drain.

The tile industry standards also require the waterproof membrane of the shower receptor be sloped properly to drain, but it's still a plumbing code requirement and is, technically, to be done by, and is the responsibility of, the plumber. Good luck with that.

If you are planning to do the pre-slope and liner yourself, and if that is permitted in your code compliance jurisdiction, you'll want that drain set such that the minimum thickness of the deck mud for your pre-slope is 3/4ths of an inch. You'll add a cleavage membrane (moisture barrier) and expanded metal lath to the plywood subfloor prior to placing your sloped mud bed.

But you are correct that your plumber is apparently ignorant of his own professional standards in this case and he should re-set the drain to the required height.

My opinion; worth price charged.

cx is online now   Reply With Quote
Unread 09-21-2021, 09:01 PM   #3
Registered User
Join Date: Sep 2021
Posts: 2
Hey CX, thanks so much for the response and the context, that helps a lot. Plumber is coming back to tomorrow, keeping my fingers crossed. Best, Jen
jllinny is offline   Reply With Quote

Stonetooling.com   Tile-Assn.com   National Gypsum Permabase

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Preslope / Shower Drain Height bgouin Tile Forum/Advice Board 1 08-13-2021 09:16 AM
drain height in subfloor RonBlake Tile Forum/Advice Board 3 11-21-2012 07:31 PM
Proper riser height for Kerdi drain and insulation question. jas_il Tile Forum/Advice Board 5 11-02-2010 05:24 PM
Matching Height, Subfloor, Thin Set Question awiese Tile Forum/Advice Board 2 05-05-2010 09:36 AM
Drain and preslope question RonT Tile Forum/Advice Board 27 09-10-2007 07:14 AM

All times are GMT -6. The time now is 08:13 PM.


Powered by vBulletin® Version 3.7.4
Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.
Copyright 2018 John Bridge & Associates, LLC