# Back-to-back shower valves on a rated party wall?



## Yikes (Jan 29, 2010)

I have a floor plan (California Building Code/ IBC) that shows accessible showers with pressure-balance mixing valves installed back-to-back between apartment units (fire barrier - 1 hour rating).

A lot of the valves that I see in brochures require a large circular cutout in the wall membrane.  Normally I would "box out" with Type X gyp behind such a large cutout to preserve the fire rating, and offset the valves into different stud bays.  However, the sate approved accessible shower stall only gives me an 8" wide area in which to place the valves, probably not enough to offset them.

Does anyone now how to maintain a fire rating at a shower valve?  Or where I can find a shower valve that does nto have such a large cutout?


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## D a v e W (Jan 29, 2010)

Re: Back-to-back shower valves on a rated party wall?

Yes, tell the designer to correct and submit the change for approval. Do not design it for them.


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## Yikes (Jan 29, 2010)

Re: Back-to-back shower valves on a rated party wall?

Well, thanks Dave, but I AM the designer; I'm not a building official.  Before I redesign the plans, i'm just asking if anyone's seen an acceptable alternative method of doing back-to-back shower valves.


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## north star (Feb 1, 2010)

Re: Back-to-back shower valves on a rated party wall?

*Yikes,*

*You might to contact the BO in your locale to see if there are other alternative types*

*of construction / fabrication that s/he would accept.   Something customized*

*possibly...  maybe enclose the shower mixing valve with a custom made stainless*

*steel, fully sealed enclosure box thingy. :?:*


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## JBI (Feb 1, 2010)

Re: Back-to-back shower valves on a rated party wall?

Yikes - Do you hav enough room to move the stall over and keep the valve assemblies for each unit inside the rated wall? BTW, I'm confused... is this a 'party wall' as the topic implies? Or just a rated assembly - fire wall, fire barrier... ?


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## fw. (Feb 1, 2010)

Re: Back-to-back shower valves on a rated party wall?

Build another wall in front of the fire wall and install the shower valves in that wall.


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## Yikes (Feb 1, 2010)

Re: Back-to-back shower valves on a rated party wall?

JD - my apologies for using the word "party wall", I forgot that in the IBC "party wall" has a very specific code meaning.  (I'm still saying the long goodbye, finishing construction on projects under the old UBC, where "party wall" was justa colloquialism.)

No, it's just a unit separation wall - -a fire barrier.

I was hoping somebody would say, yes I've seen a mixing valve that doesn't require a 6" dia. cutout in the drywall.

My first instinct was to flip the roll-in showers in alternate apartments so that the valves would end up in different stud bays.  However, I will end up with other clearance issues.

* Originally, the project was designed for bathtubs, which require 4' clear adjacent for wheelchairs... and the plumbing on the non-rated end wall of the tub.

* The owner changed it to roll-in showers, which require 5' clear, and in the current design, that means about 8" of clearance borrows kneespace from under the nearby wall-hung lavatory.  That's fine facing in one direction, but if I flip the shower on the other side of the wall, a person in a wheelchair won't reasonably be able to use the fold-down seat, because the BACK of the wheelchair can't use the lav kneespace.

Sorry to turn a plumbing question into an accessibility issue, but it's all interrelated.


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## cda (Feb 1, 2010)

Re: Back-to-back shower valves on a rated party wall?

how much space is there between the two valves???


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## cda (Feb 1, 2010)

Re: Back-to-back shower valves on a rated party wall?

http://www.gp.com/build/PageViewer.aspx ... 3&pid=6263


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## Yikes (Feb 2, 2010)

Re: Back-to-back shower valves on a rated party wall?

A typical pressure balance valve requires about 3 1/8" from the face of finish to the back wall of the water pipe.

The fire barrier (STC 50 sound) wall is 2x6 studs, plus 1/2" resilient channel on one side, plus 5/8" X gyp on each side, plus at least 1/4" for finish surface each side (perhaps Kerdi + thinset tile), total 7 1/2" wall thickness.  That means if I do back-to-back, I have 1 1/2" to spare for a 1-hour wall.


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## cda (Feb 2, 2010)

Re: Back-to-back shower valves on a rated party wall?

maybe use the calc thing to achieve the one hour needed, just at that point

721.2.1.4 and table 721.2.1.4(2)  2006 IBC


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## Batwood (Feb 17, 2010)

Re: Back-to-back shower valves on a rated party wall?

They do have listed water resistant, Fire Barrier Intumescent Putty pads. I’ve never seeing them applied in this application but you could get an engineering judgment for it and submit it to the AHJ and see if they approve it.


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