[Greenbuilding] roof venting

[Frank Tettemer]

Hey Clarke, Here in Ontario there has been a cheap (but plastic!) 
product developped a decade back. It's a skimpy sheet of styro, like an 
egg carton thick, and factory-molded like an egg carton, to form a pair 
of ventilation throughways. These things get stapled to the underside of 
the roof, between rafters or joists, with the first one's "drip-line" 
outside in the soffit area. Each one staplled up is "shingled" in such a 
way that any mpisture above the styro, eventually drips out the 
un-insulated but Vented! soffit area.
At the peak of the roof, VicWest makes a fantastic metal box-like vented 
roof ridge, that carries ventilation from the soffit through and out the 
ridge.
Styro rafter vents are called Moore Vents in this area, cover about 22" 
x 32" area, cost about a buck each.
Put up batts, or blown in cellulose, those plastic vents do it.

( Aside: Twenty years ago, addressing this same concern for 
condensation, I made up a batch of "Moore Vents" out of scrap wood and 
card board.
Laborious. But no problems with it over it's life so far.
I pay the dollar for the store-bought ones now, gladly.)

Here's a picture of the VicWest Vented Ridge, on page two, very bottom 
left corner:
http://www.vicwest.com/sites/default/files/Res_SR_SnapRib_Ultravic_Install_Guide.pdf
Here's a simple video of a guy putting the Rafter Vents up:
https://www.youtube.com/watch?v=5DX25Vz2jDc

Frank Tettemer
Living Sol ~ Building and Design
www.livingsol.com
613 585 3661


On 21/01/2017 1:02 PM, Clarke Olsen wrote:
> I am building a 750 sqft building with two single plane (shed) roofs, 
> using 12" I joists @ 3/12 pitch.
> Can we just stuff that 12" with Roxul, or is ventilation needed?
> Clarke Olsen
> clarkeolsendesign.com <http://clarkeolsendesign.com>
> 373 route 203
> Spencertown, NY 12165
> USA
> 518-392-4640
> colsen at taconic.net
>
>
>
>
>
>
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