HomeMy WebLinkAboutCOR-2000-Vapor Retarder - APR. -28' 00 (FRI) 14:01 ORB ORGANIZATION ING TEL:425-226-9115 P. 001
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THE ORS OS.GA3W=9:ATZOIhT, IMC_
w'31" a ARCHITECTS • PLANNERS • ENGINEERS
Anacortes Planning &Community Development Dept. 28 April 2000
Permit Center
P.O.Box 547, Anacortes, WA 98221
Attn: Don Measamer
Fax (360)293-1938
Ref: Repair and Renovation, 22°d&23`°Street Units
Vapor Retarder
Sir, ,
We were contacted today by Steve Jaffray of Anacortes Housing Authority regarding a question
asked during an inspection today by your office. The inspector apparently asked why we specified
a 6rad polyethylene vapor retarder to be applied over the exterior wall and roof insulation prior to
installation of gypsum board. He apparently felt that the kaft paper facing on the insulation was
sufficient and the poly was "overkiIr".
Kraft paper facing has a reasonably low perm rating but, unless all seams and penetrations are
taped, provides no effective vapor retardation. Polyethylene has an effective perm rating of 1.0,
with all seams raped, and is routinely used in this application,- The kraft faced insulation was
specified only for the convenience of insulation applicators, so they have something to fasten the
batt in with so that it does not shift before the wall assembly is completed. Without an effective
vapor retarder moisture will always migrate from the warn side to the colder side of an assembly
and will condense within the wall when it reaches its dew point, with resulting wetting and loss of
effectiveness of the insulation. Much literature exists on this subject, I would be happy to provide
you with some material on the subject.
Please feel free to call if you wish to discuss this issue further. pp
Sincerely,
The ORB Organization, Tnc.
John Patterson by r„1zW - �-� C� /J t u kc 4"
Project Manager /
CC: Steve Jaffray(360)293-8998
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607 SW Grady Way,SIIlIL 210,Benton,Washington 98055-2977/(425)226-3522/FAX(425)226-9115 - I