[Greenbuilding] Insulated overhangs

Kat molasses at q.com
Thu Mar 10 14:45:43 PST 2011

Can't say as I've ever seen the problem you're describing, whether open 
or closed soffit... except maybe at the beach? Everything's water and 
salt-stained there - I couldn't tell you if it was the same problem, 
though. I haven't a clue as to how it would happen, assuming you're 
talking about mildew forming on the outside of the soffits? Are you 
saying the moisture is coming from outside? So moisture is condensing on 
the outsides of the soffits? Why does air sealing and insulation stop it?


> If you mean design with open rafter tails I have done that and it 
> doesn’t remedy the moisture problem under the eaves (exterior air 
> problem). If you mean open ‘the’ rafter tails as a means of foaming in 
> insulation – can’t do that easily with this building (hip roof big 
> continuous fascia w/ integrated gutters)
> /4465 UPHILL RD//,. DUNCAN, B.C. CANADA, V9L 6M7/
> /PH 250 748 7672 FAX 250 748 7612 CELL 250 246 8541/
> /terrain at shaw.ca///
> ------------------------------------------------------------------------
> *From:* smarbawa at gmail.com [mailto:smarbawa at gmail.com] *On Behalf Of 
> *Alan Abrams
> *Sent:* March 8, 2011 5:01 AM
> *To:* Green Building
> *Subject:* Re: [Greenbuilding] Insulated overhangs
> open rafter tails...
>     I’ve made it a practice in the pnw to air seal and insulate
>     overhangs – especially large overhangs or porches. It seems like a
>     waste but too much moisture and potential for condensation =
>     mildewy soffits. Builder neglected to do this on a project and now
>     the wood soffits are getting saturated and staining. I am looking
>     for a solution to recommend to the client short of removing all
>     the soffit material. I am considering removal of a few soffit
>     boards to allow for foamed insulation but don’t have personal
>     experience with how effective it could be to form an air barrier
>     or how well it can be done to fill the area. The soffit wood is
>     natural t&g so cannot reliably be sealed on the exterior.
>     Any thoughts or recommendations?
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