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<body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div>Clarke;</div><div><br></div><div>I trust that you would do a competent job of air-sealing and building a good roof but $#!+ happens and water in all of its forms is amazing in its ability circumvent/overcome humans' efforts to exclude it from their structures.</div><div><br></div><div>Low slope, unventilated I-joist roof in a heating climate in snow country ? I'd say that's like playing Russian Roulette with five bullets in the magazine of a six-shooter.</div><div><br></div><div>One scenario that could throw a curveball into the good intentions: -- large accumulation of wet snow on the roof during an unusual weather event causing excessive deflection in the relatively skinny I-joists stressing the painted taped joints in the drywall compromising the integrity of the interior air barrier. Same snowfall results in ice dams and or ponding subjecting the roof cladding to conditions that it was never intended to deal with.</div><div><br></div><div>That's just one possible scenario leading to moisture intrusion into the framing cavity jammed full of Roxul. The Roxul would be fine... eventually... once the moisture drains out of it and gets cooked off ... but the gumboard webs of the I-joists and gumboard roof sheathing would likely be an unholy mess of black flakes in time.</div><div><br></div><div>As that wonderful woman Meryl Streep once shouted out , after she and her two co-stars had belted out some disco-era tunes while the movie credits were rolling "YOU WANT MORE ??!!!" </div><div><br></div><div><br></div><div><br></div><div>On Sat, 21 Jan 2017 13:02:05 -0500, Clarke Olsen <colsen@fairpoint.net> wrote:<br></div><br><blockquote style="margin: 0 0 0.80ex; border-left: #0000FF 2px solid; padding-left: 1ex">I am building a 750 sqft building with two single plane (shed) roofs, using 12" I joists @ 3/12 pitch. <div>Can we just stuff that 12" with Roxul, or is ventilation needed?</div></blockquote><br><br><div id="M2Signature"><div>-- </div><div>=== * ===<br>Rob Tom T6015O<br>Kanata, Ontario, Canada<br><br>< A r c h i L o g i c at Y a h o o dot C a ><br><br>(manually winnow the chaff from my edress if you hit "Reply")</div></div></body></html>