Re: need help

Started by Amanda_931, July 19, 2006, 09:34:35 PM

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I'm thinking for me that I want space between the metal roof (which may or may not be self-venting--the ag style roof without the foam under the ridge is, but for other reasons you don't want ag style) and my insulation.

possiblities include:

sheathing with OSB or something similar.  putting the roofing on with or without purlins.

and/or those plastic foam channels,

somewhere John has posted instructions for venting the top of most any kind of roof--from Core-A-Vent?--that or one of its competitors.

Then put batts or one of the foam insulations or damp cellulose or.....  then the ceiling of the kind I have down at the barn--half-lap joints in any of several widths of rough-sawn boards, I'm thinking that three different widths would be nice.  That I may get around to whitewashing one of these years--barn sure hasn't been done yet..

Icynene and some soybean derived foam are the hot choice.  The latter is supposed to use water as the blowing agent--nice if you might be sensitive to the blowing agent in Icynene (severe asthma when I worked near leaky paint booths do not exactly make that a welcome choice, although for most people since it must be professionally installed, there'd be none left after came in that night to inspect)  I expect that the soy-derivitive is even more expensive than the Icynene.  Both need professional installation.


How deep are your rafters and are you using an inside ceiling -- the metal roof ribs should provide venting I would think unless you put seals at the top and bottom -- may at least want to screen the ribs for critters though.

You could just staple the insulation low enough on the joist to leave air space above if the rafters are deep enough.