Vapor Barriers in Phoenix?

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phoenix

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Remodeling a house in Phoenix. Our framer didn't install a vapor barrier or house wrap between osb sheathing and the exterior siding (t-111). City inspector is requiring it because "you do not want water penetrating from the outside into the wall cavities because it will rot the insulation." Inspector says I can install felt paper in the wall cavities to pass inspection. A few questions. 1. Do I need a vapor barrier in Phoenix? 2. If yes, will installing felt paper in the exterior wall cavities provide an adequate vapor barrier? The reason I ask is, I want to use open celled foam as my insulation, and that stuff is like a sponge I guess. Any thoughts or recommendations are appreciated.
 
Welcome to the site.
Rules will be different in Phoenix so I will leave that to others.
BUT this is a pretty dumb mistake, even a framer should know about house wrap and it leaves some other questions like flashing and door, proper installation of the doors and windows. I would want a redo at no charge.
 
Sounds like a bunch of trouble to me, but it's your house. Open cell foam depends on what your climate is as to whether or not you need a vapor barrier, which is not to be confused with an exterior weather barrier.
The tar paper should not be used in between the studs..it defeats the purpose of the weather barrier which needs to be a continuous piece which is overlapped at any seams.
Learn a bit more about the differences, so you can talk to your building official and possibly educate them about the differences. I don't think they understand.
 
Well. depends on your humidity and rainfall . how big are the overhangs?
The reason is splashing on the siding, and t-1-11 is really an outbuilding siding.It never works well with window installation and penetrations.
Short of redoing, there really aren't any good options. Usually it is sided over with vinyl at some point, and the t-111 is treated as the plywood underneath.

Here is some information.
http://bct.eco.umass.edu/publicatio...-felt-paper-and-weather-penetration-barriers/
 
Thanks InspectorD. Reading the article, it says "Your local code may not require you to use felt or housewrap, but unless you live in an extremely arid climate — you need to use it." Phoenix is pretty arid. I have been researching alternatives and saw some moisture barrier paint. What about using a moisture barrier paint? Also, I said I was using t-111 cause that's all I know. I think it's actually called smart siding.
 
Welcome to the forums! No other options, IMO;

Under 2006 IBC; http://www.cmdgroup.com/building-codes/arizona/

WRB and flashing, as said above; http://publicecodes.cyberregs.com/icod/ibc/2006f2/icod_ibc_2006f2_14_par010.htm

" 1405.15 Fiber cement siding.

Fiber cement siding complying with Section 1404.10 shall be permitted on exterior walls of Type I, II, III, IV and V construction for wind pressure resistance or wind speed exposures as indicated in the manufacturer’s compliance report and approved installation instructions. Where specified, the siding shall be installed over sheathing or materials listed in Section 2304.6 and shall be installed to conform to the water-resistive barrier requirements in Section 1403. Siding and accessories shall be installed in accordance with approved manufacturer’s instructions." Bold is mine, from; http://publicecodes.cyberregs.com/icod/ibc/2006f2/icod_ibc_2006f2_14_par058.htm

From manufacturer; "27. Can LP® SmartSide® siding be fastened directly to the studs?
a. Certain LP SmartSide products can be attached to framed walls without sheathing such as Precision series siding. Refer to the LP SmartSide installation instructions for the specific type of LP SmartSide siding you are using. Note that a code-approved breathable water-resistive barrier is required between the siding and the studs." from; http://www.lpcorp.com/Resources/Lit...Sales_Sheets/LP_SmartSide_Trim___Siding_FAQs/ Bold, again, is mine.

The building paper/house wrap is the exterior water barrier after the siding, draining the wall- covering the stud/plate faces. An interior vapor retarder is recommended for your location, but not a true "vapor barrier" (Class 1) mirrors, foil wallpaper, etc. to stop exterior water vapor and condense in the stud cavity with the AC on; http://www.buildingscience.com/documents/reports/rr-0410-vapor-barriers-and-wall-design

Kraft paper (asphalt) faced insulation batt is fine; Fig.#6; http://web.ornl.gov/sci/roofs+walls/staff/papers/143.pdf

Gary
 
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