Re: [GBlist] RE: SIP roofs rot in wet climates

[Frazer Dougherty <fdougher@optonline.net>]

Mark - Builders do not install ceilings before the roof goes up & hopefully
they have weathersealed (shingled) the roof as well. And soffits are not
considered to be within the conditioned envelope so why would you want a
'warm-side vapor barrier' there ??

The point is that warm (& moist) air moves to the gaps in the SIPs thru
stack effect and begins to condense & eventually will grow mold, rot,
delaminate, etc the SIPs, OSB, etc.

So one has two choices - seal the shit out of the SIPs gaps or prevent stack
effect. We know that neither is really possible by itself  - so one has to
do both (the 2nd is ventilate right, but it seems we are all still looking
for the third possiblity). Check any reasonably good window or door &  you
will see 2 sets of weatherstripping, sometimes 3 or just look at your car
door next time you get in.
---------------------------------
Frazer Dougherty
North Fork Retrofit & Solar Options
Mail - Box 4016, East Hampton, NY 11937
Ship - 75 Industrial Rd, Wainscott, NY 11975
t.  631.537.1654
f.  631.537.1637
c. 631.645-3534
fpd@solaroptions.com
www.solaroptions.com
Insight '00, citrus yellow, 60.8 lmpg


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