<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">Hi, Reuben—<div class=""><br class=""></div><div class="">There is a small gap between the drywall and the framing, which, when you think about it, can be hundreds of feet long. So for example, air will flow between drywall and sole plate at floor level, and rise inside the wall cavity. Same with all the penetrations for light fixtures, electrical switch and outlet boxes. It can add up, but it’s easy to seal during installation.</div><div class=""><br class=""></div><div class="">Best,</div><div class=""><br class=""></div><div class="">Mike</div><div class=""><br class=""></div><div class=""><br class=""><div><div class="">On Dec 11, 2016, at 12:49 PM, Reuben Deumling <<a href="mailto:9watts@gmail.com" class="">9watts@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class="">Are we talking about air- or moisture-tight drywall? I guess I'd have
thought that taping the seams, never mind priming and painting, would
take care of the air permeability pretty well. </div><div class="gmail_extra"><br class=""><div class="gmail_quote">On Sun, Dec 11, 2016 at 9:19 AM, Michael O'Brien <span dir="ltr" class=""><<a href="mailto:obrien@hevanet.com" target="_blank" class="">obrien@hevanet.com</a>></span> wrote:<br class=""><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word" class="">Hi, guys—<div class=""><br class=""></div><div class="">Airtight drywall or ADA was originally based on an idea of Gus Handegord’s that was first implemented by Joe Lstiburek and his partner at the time. Their first trials used plywood to bridge between drywall sheets in back of framing junctions, and an acoustical sealant to seal drywall to framing. Since then it has developed into several different versions, but I would give them credit for starting it way back in the ancient 1980s. </div><div class=""><br class=""></div><div class="">Best,</div><div class=""><br class=""></div><div class="">Mike O'Brien</div><div class=""><div class="h5"><div class=""><br class=""></div><div class=""><br class=""><div class=""><div class="">On Dec 11, 2016, at 8:29 AM, Norbert Senf <<a href="mailto:norbert.senf@gmail.com" target="_blank" class="">norbert.senf@gmail.com</a>> wrote:</div><br class="m_-7554925113145473280Apple-interchange-newline"><div class=""><div dir="ltr" class=""><div class=""><div class=""><div class=""><div class=""><div class="">Here's one way:<br class=""><br class=""></div>- strip off the tongue and groove.<br class=""></div>- Add a vapor barrier (6 mil poly). Research the proper details to seal the joints in the plastic. Here they use acoustical sealant. <br class=""></div>- a good way to handle wiring, etc. is to put 2x2 strapping on top, to provide a chase so you don't have to penetrate the plastic. It also avoids a gazillion nail holes in the plastic from the tongue and groove. The real pros will use acoustical sealant where the strapping is nailed to the rafters.<br class=""></div>- pay particular attention to all the edge details.<br class=""><br class=""></div>There is another approach I have seen, which is airtight drywall. You need foil backed drywall, plus gaskets. I believe it was developed at the University of Illinois................<wbr class="">Norbert<br class=""></div><div class="gmail_extra"><br class=""><div class="gmail_quote">On Sat, Dec 10, 2016 at 9:20 PM, Leslie Moyer <span dir="ltr" class=""><<a href="mailto:unschooler@lrec.org" target="_blank" class="">unschooler@lrec.org</a>></span> wrote:<br class=""><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="font-family:Arial,sans-serif;font-size:10pt" class="">So it sounds like you're all pretty much in agreement that an air barrier will fix the problem. It seems to me that they have NO air barrier now--good, bad or otherwise. I.e. they don't have penetrations in their air barrier--they don't HAVE an air barrier. The layers in the roof/ceiling assembly my friend describes below are the ENTIRETY of the construction....he listed everything in order as it is. As far as vapor movement goes, they are aware that the Roxul is not a vapor barrier and neither is the tongue and groove ceiling. <span style="font-size:10pt" class="">I was leaning toward a "thermal bridging" problem & thought rigid foam insulation would fix it...either under the boxcar siding or under the roof sheathing. </span><div class=""><span style="font-size:10pt" class=""><br class=""></span></div><div class=""><span style="font-size:10pt" class="">There are no can lights in the ceiling. There is wiring in place for one fixture, I believe, but no other large holes. I'm not sure, but I don't think they have drywall under the tongue and groove boxcar siding on the ceiling--he didn't mention it below and he didn't mention it in his conversation with me earlier today.</span><div class=""><div class=""><br class=""></div><div class="">This is a brand new addition--unfinished still--and they are not looking for a short-term fix. The builder just left and is willing to come back to fix the problem now, but they need to come to an agreement about what that "fix" will entail. <br class=""><div class=""><br class=""></div><div class="">So, for a solution, they need to air seal all holes of any size that go from the sidewall plates up into the ceiling; air-seal all holes that penetrate into the ceiling. Where, exactly, should the air barrier be installed? "The warm side" doesn't tell me enough--there are several layers on the warm side. They need to know if they should approach this by removing the metal roofing & sheathing and go in from the top, or remove the tongue and groove siding on the ceiling and fix things from the inside-out. </div><div class=""><br class="">-Leslie Moyer<br class=""><br class="">--- <a href="mailto:obrien@hevanet.com" target="_blank" class="">obrien@hevanet.com</a> wrote:<br class=""><br class="">From: "Michael O'Brien" <<a href="mailto:obrien@hevanet.com" target="_blank" class="">obrien@hevanet.com</a>><span class=""><br class="">To: Green Building <<a href="mailto:greenbuilding@lists.bioenergylists.org" target="_blank" class="">greenbuilding@lists.bioenergy<wbr class="">lists.org</a>><br class="">Subject: Re: [Greenbuilding] Unvented cathedral ceiling condensation<br class=""></span>Date: Sat, 10 Dec 2016 13:38:28 -0800<span class=""><br class=""><br class="">Hi, Leslie—<div class=""><br class=""></div><div class="">Just wanted to chime in to agree about the air leaks across the interior side of the cathedral ceiling. Not only recessed can fixtures, but often every wiring hole drilled through top plates, every vent stack and flue have not been sealed to block air leaks. The walls may be contributing, too, if there are penetrations in the top plates. </div><div class=""><br class=""></div><div class="">The long-term fix is to take down the ceiling drywall so the leaks can be sealed and a proper vapor rertarder installed, but in the short term they could run a dehumidifier to reduce the water vapor in their occupied space. </div><div class=""><br class=""></div><div class="">Sometimes builders will open up the blocks along the eaves and install some sort of vent at or near the ridge, but this may have the effect of sending cold air under the insulation and cooling down the interior surface of the ceiling, it takes some detailing to keep the vent air above the insulation.</div><div class=""><br class=""></div><div class="">Best wishes,</div><div class=""><br class=""></div><div class="">Mike O’Brien</div><div class=""><br class=""></div><div class=""><br class=""></div></span><span class=""><div class=""><br class=""><div class=""><div class="">On Dec 10, 2016, at 11:50 AM, Leslie Moyer <<a href="mailto:unschooler@lrec.org" target="_blank" class="">unschooler@lrec.org</a>> wrote:</div><br class=""><div class=""><div style="font-family:Arial,sans-serif;font-size:10pt" class=""><div class=""><span style="color:rgb(49,49,49);font-family:Roboto;font-size:16px;word-spacing:1px;background-color:rgb(255,255,255)" class="">I have some nearby friends having a problem. I think I understand what the problem is, and even some possible ways to solve it, but I'm not certain I could give them advice that would fix their problem the best or cheapest way. I thought you guys could, though! </span></div><div class=""><span style="color:rgb(49,49,49);font-family:Roboto;font-size:16px;word-spacing:1px;background-color:rgb(255,255,255)" class=""><br class=""></span></div><div class=""><span style="color:rgb(49,49,49);font-family:Roboto;font-size:16px;word-spacing:1px;background-color:rgb(255,255,255)" class="">They read this article & I think they will go ahead and pay to read the article referenced within it: </span></div><div class=""><span style="color:rgb(49,49,49);font-family:Roboto;font-size:16px;word-spacing:1px;background-color:rgb(255,255,255)" class=""><br class=""></span></div><span style="color:rgb(49,49,49);font-family:Roboto;font-size:16px;word-spacing:1px;background-color:rgb(255,255,255)" class=""><div class=""><a href="http://www.greenbuildingadvisor.com/blogs/dept/musings/how-build-insulated-cathedral-ceiling" target="_blank" class="">http://www.greenbuildingadviso<wbr class="">r.com/blogs/dept/musings/how-<wbr class="">build-insulated-cathedral-<wbr class="">ceiling</a></div><div class=""><br class=""></div><div class="">We are considered a "hot humid" climate--NE Oklahoma </div>…………………………….</span><br style="color:rgb(49,49,49);font-family:Roboto;font-size:16px;word-spacing:1px" class=""><br style="color:rgb(49,49,49);font-family:Roboto;font-size:16px;word-spacing:1px" class=""><span style="color:rgb(49,49,49);font-family:Roboto;font-size:16px;word-spacing:1px;background-color:rgb(255,255,255)" class="">We have a question regarding condensation problems in a cathedral ceiling. We live in northeastern Oklahoma (zone 3) and just added a dinning room (cathedral ceiling) 15 x 19 addition. The addition was just opened up to the main house earlier this week, and we got hit with (what are for us) very cold temperatures. Thursday night had a low of 12 F. By noon on Friday we noticed that water was dripping down the north side interior wall (along the drywall). The drip lines appeared to be spaced every 24 inches, or about where a roof rafter would be.</span><br style="color:rgb(49,49,49);font-family:Roboto;font-size:16px;word-spacing:1px" class=""><br style="color:rgb(49,49,49);font-family:Roboto;font-size:16px;word-spacing:1px" class=""><span style="color:rgb(49,49,49);font-family:Roboto;font-size:16px;word-spacing:1px;background-color:rgb(255,255,255)" class="">The ceiling/roof construction was constructed with 2 x 8 rafters and insulated with R30 Roxul (rock wool) insulation and is not vented. The interior ceiling is wooden tongue and groove car siding. The roof decking is LP TechShield Radiant Barrier (with the metal foil side facing the interior of the house, as described on the boards) with a metal roof (there is felt paper in between the decking and the metal roof on the North side, but on the South side we used double bubble). We did not have any condensation issues on the south wall.</span><br style="color:rgb(49,49,49);font-family:Roboto;font-size:16px;word-spacing:1px" class=""><br style="color:rgb(49,49,49);font-family:Roboto;font-size:16px;word-spacing:1px" class=""><span style="color:rgb(49,49,49);font-family:Roboto;font-size:16px;word-spacing:1px;background-color:rgb(255,255,255)" class="">We have spoken with over half a dozen different experts, and we’re getting as many different suggested solutions. We are desperate to fix this problem and would greatly appreciate any help! Thank you!</span></div>______________________________<wbr class="">_________________<br class="">Greenbuilding mailing list<br class="">to Send a Message to the list, use the email address<br class=""><a href="mailto:Greenbuilding@bioenergylists.org" target="_blank" class="">Greenbuilding@bioenergylists.o<wbr class="">rg</a><br class=""><br class="">to UNSUBSCRIBE or Change your List Settings use the web page<br class=""><a href="http://lists.bioenergylists.org/mailman/listinfo/greenbuilding_lists.bioenergylists.org" target="_blank" class="">http://lists.bioenergylists.or<wbr class="">g/mailman/listinfo/greenbuildi<wbr class="">ng_lists.bioenergylists.org</a></div></div><br class=""></div>______________________________<wbr class="">_________________
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