Proper Backer Boards for showers in Pittsburgh, PA
Mtcummins you seem to be a little slow understanding the TTMAC and ANSI Specifications.
Neither of the industries top organizations include drywall in shower construction. When drywall is referenced it makes further notation to include the words "Dry Area Only".
In the shower receptor drawing details as well dry wall is not listed.
So to repeat.
You can use water poofing over drywall, Kerdi, Hydro Ban and Aqua Defence etc. - just not in showers. Schluter does have men working in these orgaazations and if drywall was accepted in a shower they would have included it in the manuals. But they didn't because it is not accepted.
Your in Pittsburg, PA - in Pittsburgh your local Bureau of Building Inspection - (412) 255-2175 can offer you more guidance on proper shower construction procedures. I spoke with them this morning and Pittsburgh follows the International Building Code. The International Building Code removed drywall from acceptable backer boards in showers a few years back - I guess you missed the memo. If you order that code book you will not find drywall listed under shower backer boards. Maybe try emailing the building department and asking them if it is OK. BBI_DPWRequests@city.pittsburgh.pa.us
I got a hold of Eric in the Inspection Burea and we discussed this. I was told that in Pittsburgh a single family home would fall under the IRC. Under showers and tubs it mentions something like a non-absorbat backer board material is to be used.
Dry Wall is not non-absorbant. We discussed vapour barriers and his take on them and at the end of the call I asked him what he would use in his own shower if building new. Eric said cement board or wonder board.
I would think this very loose text in the building code would open the doors up to many crazy designs.
If you read this Document from Gypsum Nexus you might fell a bit better about not understanding all the new code changes. At the bottom of the first page on the right it makes mention that Green Board (water resistant) drywall is permitted in a bathroom renovation but not in the "Wet Zone".
So you have the people that make drywall say No - drywall is not allowed in wetzones of showers.
You have the International Building Codes change to exclude drywall from the Wet Zones
You have TTMAC and ANSI repeating the fact that drywall is not to be used in wet zones
You have the IRC stating a non-absorbat material is to be used.
And you have Schluter (and others) saying drywall is an approved substrate. Of course they say that because sometimes people like me like to waterpoof more than just the wetzone and we bring our membranes out past the backer boards.
I hope this helps.
Kerdi does wick water as you can clearly see in these pictures
That is a Schluter install book. Not a code book. You must then think it's OK to build a shower curb out of 2"x4" 's and drywall as well I'm thinking. If you kerdi it of course. I heard about a hotel in Las Vegas that tried that. They failed and replaced them with Noble Showers, or so I'm told.
The book (Schluter Shower Handbook) also shows water beading on Kerdi when it actually wicks.
Here is a picture of drywall and Kerdi Board wicking water. I find it interesting that the kerdi Board wicks water more than drywall. Don't you?
Look how Kerdi wicks the water above the flood line.
Someone posted once Kerdi is Magic and it doesn't leak even with a pinhole. I tested this theory as well and to be fair tested Noble Seal TS - guess what? They both leak when poked with a hole.
Did you can your inspector to find out if you can use drywall in Pittsburgh, PA? I emailed them for you in case your too busy.I'll post the info once I hear back. Can't wait to hear what your local inspector thinks. Probably tell me "No".
How many showers have you build in Pittsburgh with drywall? Did you mud and tape the seams? Can you use Kerdi over drywall mud or does it just have to be the plain paper? http://www.nationalgypsum.com/resour...pWallBoard.pdf Great Dry Wall resource. Funny no mention of Kerdi and a shower detail??? Seems like the only place that says you can use drywall in a shower is in the company handout? Odd. Imagine if you followed the advice and built your curb with drywall over 2"x4" studs? What a recipe for disaster.
Checking with Building Departments and Building Bureaus first before selecting backer
Kerdi is not approved over drywall. Only Schluter states this.
If your local building inspector allowed it once does not make it acceptable. I'll check in on a few bureaus in New England and ask Jim's inspectors if they allow it.
Promoting shower's build with drywall is crazy. If 10 people purchase cement board and flood test their shower build - I've already made a difference. I've helped dozens of people flood test their own showers in the past year. Most of whom live in another city and another country - Yours.
People want to build better. People are tired of paying for crap and paying well for it.
Mtcummins and Jim you have sent me off on a new baby mission. Lets call around a few cities and ask the building departments what they allow. No offence to you men but I doubt any of you have even build a shower in the last 24 months let alone waterproofed one. Can either of you show me some install pictures of a shower build with drywall and a flood test report signed off on by an inspector? I won't hold my breath. While you sort that out I'll keep calling for flood test inspections and sharing inspector reports. You keep selling the drywall angle and I will call a new city each morning and will do a survey of sorts.
Can dry wall be used in a shower - Does the TTMAC ANSI approved it?
MTCummins when you install tile and want to check your coverage rates you left a tile up to see. You want at least 80% coverage.
The simple act of lifting a tile causes suction. Like a shop vac pulling on one spot.
In your "Code Book" or "Schluter Hand Book" to use a proper name Schluter mentions that tile can be installed right away. Have you ever vaccumed Kerdi the next day? The same day? Do you know what happens when you vacum fresh Kerdi? The Kerdi pulls away from the substrate.
Now because Schluter says it's OK to set tile right away I don't. Not because I don't think the Kerdi will fail this process, but because I know Kerdi will fail this process. How do I know? I installed Kerdi for a decade.
The Schluter handbook also lists a flood inspection if nececessary. They are.
Jim put up an ICS report that said Kerdi can be installed over drywall. An ICS report is used to get a IAPMO Certification. The IAPMO certification is key, not the ICS. Yet you need the ICS to obtain the IAPMO.
In no industry specification book does it show a shower built with drywall.
Yes you can set Kerdi or a liquid membrane over drywall. If it is for something other than a shower, is in a non wet zone and is interior not exterior.
I have found that thin set does not bite well to drywall that has been mudded? When we set tile over drywall we vaccum it for bond breakers, wash it gently and use a high quality modfied thinset. Some times we first prime the drywall. Schluter does not spec the process of the drywall and with this insane set up you have a gypsum board producer, a waterproofing membrane and a thinset company in the mix. If you wanted to go against all industry guidelines and use drywall, One would reason that using juts products from Laticrete, Custom or Mapei would make more sense.
I spoke the other day with my Mapei rep and he thinks drywall is a horrible idea in a shower. He warned me against moisture vapour building up and failing the back side of the drywall. We spoke a bit about what a poor building practice this is and shock are heads in disgust that this practice goes on.
Show me any tile organzation that endorses drywall as a backer board. Not a supplier, because they are selling you something. But an organaztion that's interests are to promote proper industry standards and industry best work practices.
Have to go. I joined the ASTM and this morning is my training class!
Is Dry Wall allowed in Boston as a backer board?
Jim I have tested all liquids with drywall and they pass flood tests as well. I make simple boxes to check new stock.
What you seem to ignore is that Schluter does not set industry guidelines. Even with some of their top staff on these organization boards you do not find drywall listed as a backer board in any organization. This is my point and the point you seem to skirt at every post.
Drywall is not an approved backer board in wet zones (TTMAC & ANSI). If it was it would be listed with an elevation detail. If you can show me a drawing produced by TTMAC or ANSI outlining this method I'll eat crow. I'll hold tight while you find it. Until then I will continue to inform people that Dry Wall is not acceptable because it's not listed as one of the approved backer boards in any industry guideline.
Jim would you use dryall over wood studs and then kerdi to build a curb? I bet that the outside edge crumbles the first time someone steps on it. Schluter says it's OK in their handbook - is it? Do you have any expanded details from Schluter? Perhaps a line drawing? Come on Jim....
Jim here is the Boston Inspections Service's contact information;
Plans & Zoning Division
1010 Massachusetts Avenue, 5th floor
Boston, MA 02118
Tel: 617 635 5312
Fax: 617 635 5399
I sent a request for clarification for you.
Schluter's requirements for Gypsum Backer Boards - do they include corner beads?
What level of drywall finish is spec'd Jim?
Originally Posted by jadnashua
Board and metal corner bead.
Board, tape, finish mud.
Board, tape, finish mud, priming?
Pretty grey area.
Does Drywall (Gypsum) have any place in a shower renovation?
I have had more than one setter tell me that Kerdi peels away if there is any drywall mud over the board.
I have see guys scrap it all off.
One guy uses Hydro Ban first to seal the drywall.
What is required to maintain a warranty from Schluter. So if it fails your covered.
Or will it be "Kerdi is not allowed over that type of drywall compound"
Can it go over Cement Fill from Synko?
Can it cover over 30 minute?
Do curbs need outside drywall corners?
When waterproofing over a CBU we always tape the seams first. This is a required step in CBU boarding.
The use of metal corner beads and such is also required with drywall. I would think you need to follow the manfactures guidelines???
If this is all approved with the TCNA why does it not appear in the ANSI Specification guide? The new one.
Your guide is outdated I think you said Jim.
Have you men really build a curb with wood and drywall? Can you say "Hack"
Inspired by Jim's posting of his favourite backer board "Dry Wall" I thought a new series of testing should be done at the SunnyCrest Lab. I broke out a sheet of plexiglass and cut it up into small stock. I then covered each sheet with DryDex and drywall spackling compound.
This "Drydex" is great stuff. When your painting sometimes you can sand too quickly a drywall patch. This product goes on Pink and dries white.
Yesterday I set the DryDex to the plexiglass and today I will skim these samples out with regular drywall compound (Synko - Classic Finish)
I'll let these new assemblies sit for a few days and then I will Kerdi a few and use liquid on the others.
I'm going to make some boxes - cover them tight and just sit back and watch. If any of the waterproofing measures do not work with drywall the water should leak to the bottom and reactivate the DryDex and turn it pink.
Seeing is believing, and this will prove to me with no doubts if waterproofing can be applied over drywall.