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 > Professionals' Hangout


Thread Tools Search this Thread
Unread 10-24-2015, 11:51 AM   #1
South land Tile
Registered User
Join Date: Oct 2015
Location: Greenville, Ms
Posts: 115
Priming hardi backer before applying kerdi

Im one of those guys that prefer installing hardi backer but as is a commonly noted problem the thirstyness of the stuff makes hanging kerdi a pain even with sponging it before troweling thinset on. Somwhere on the forum I remember somebody mentioning in a post the possibility of priming the hardi with something like quickcrete primer or something like unto it I called laticrete tech services yesterday and asked about using nxt primer and then hanging kerdi with their 317 thinset and got a absolute no but I guess I'd like to know why it wouldn't work.
South land Tile is offline   Reply With Quote
Sponsored Links
Unread 10-24-2015, 04:09 PM   #2
Jim Cordes
Registered User
Join Date: Apr 2014
Location: Pittsburgh PA
Posts: 728
My vote is to stop using the hardi. first off other then it being thirsty it can also get moldy in a wet environment(which doesnt matter if your using Kerdi).. cement based CBU's dont and they also don't have a problem with being thristy either.

I will assume the reason you prefer hardi is becuase it is flat? Now if thats what you want. It is perfectly fine to just use drywall under the kerdi as per warranty.

If you are worried about mold and want to over build it with something that cannot feed mold..then use regular cement board. If your wanting flat and ease of installation then use drywall.

There is really no advantage to using Hardi under Kerdi. and as you have discovered there are disadvantages.
Jim Cordes is offline   Reply With Quote
Unread 10-24-2015, 04:21 PM   #3
Veteran DIYer- Schluterville Graduate

STAR Senior Contributor

Join Date: Jul 2004
Location: Nashua, NH
Posts: 14,285
Hardie is thirsty enough such that it can benefit from a garden sprayer. As long as there is no liquid water on the stuff, you have not gotten things too wet.
Jim DeBruycker
Not a pro, multiple Schluter Workshops (Schluterville and 2013 and 2014 at Schluter Headquarters), Mapei Training 2014, Laticrete Workshop 2014, Custom Building Products Workshop 2015, and Longtime Forum Participant.
jadnashua is online now   Reply With Quote
Unread 10-24-2015, 04:57 PM   #4
Kman's Avatar
Join Date: Nov 2006
Location: NW Arkansas, Ozark Mountains
Posts: 11,822
If I was going to use Redgard over Hardi, I would prime it with a diluted mixture of four parts water to one part Redgard. I think that's the ration Custom recommends for priming.

But I agree with Jim that sheetrock makes good substrate for Kerdi.

The top ten reasons to procrastinate:

Kman is offline   Reply With Quote
Unread 10-25-2015, 09:48 AM   #5
Tile & Stone
Join Date: Sep 2002
Location: Northeast/Connecticut
Posts: 2,550
Every shower repair I do that has Hardie as the backer is a mold farm. For some reason this stuff sucks up the water like there's no tomorrow. I agree with Jim's advice.

CTEF Certified Installer
I lost my hero on 5-21-16 You will be missed. Semper Fi
tilemanct is offline   Reply With Quote
Unread 10-25-2015, 11:51 AM   #6
Tile Contractor
Join Date: Jul 2001
Location: Victoria, BC Canada
Posts: 1,540
I won't use it. One time I put it in a vestibule in a store. The panels were bent from sagging on the pallet. When I installed it on perfect framing there were high and low areas between the studs. Hate to screw into it. Hate cutting it; gotta score it many times with the T-headed cutter. It delaminates if you gotta break narrow pieces AND the moisture-sucking problem.

Sorry, but I just hate it.
Terra Firma Tile
Ron is offline   Reply With Quote
Unread 10-25-2015, 12:13 PM   #7
Registered User
Join Date: Feb 2012
Location: montreal.canada
Posts: 124
The primer we are speking of?

Does it contains latex/polymers? Kerdi and polymers is a no.

Also laticrete sells their own menbrane makes sence they would not recoment their producs to apply some one else's
Alexandre G.V. Hamel. Compagnon région de Montréal
alex.h is offline   Reply With Quote
Unread 10-25-2015, 06:36 PM   #8
Dan Kramer
Registered Tile/Stone User
Dan Kramer's Avatar
Join Date: Jul 2002
Location: Outer Banks, NC
Posts: 1,592
Laticrete doesn't warranty any of their products in conjunction with Schluter's stuff. At least thats what a Lati guy told me.

If you use Hardi, do as Jim suggested and saturate the board with a pump type lawn sprayer before spreading thinset. Just make sure there is no "standing" water before application of thinset.

Use sheetrock!
Dan Kramer 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
Prepping Hardi Backer for Kerdi digitalshooter Tile Forum/Advice Board 14 02-25-2014 09:52 AM
hardi backer? chich Tile Forum/Advice Board 4 06-20-2009 06:01 PM
problem with kerdi over hardi backer board jaseweil Tile Forum/Advice Board 7 03-29-2007 04:32 PM
Hardi Backer rickr01 Tile Forum/Advice Board 6 01-03-2006 01:59 PM
Hardi backer jazzyjeff1 Tile Forum/Advice Board 14 10-16-2002 05:29 PM

All times are GMT -6. The time now is 06:34 PM.


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