消除金属屋顶的底面的凝结
我在4A区
I am constructing a post frame conditioned shop building with blow in cellulose on the OSB ceiling. Above this I will have the metal roof on 2×4 purlins.
这个地区很潮湿。在我的小元l storage sheds I had to remove the roof and put a layer of bubble foil insulation to keep condensation from falling onto my tools.
I could buy the same insulation, but it will add several hundred dollars to the build; so, I was looking for more economical solutions.
I happen to have a ton of typar housewrap on hand and plan to use it on the walls. Could this housewrap be used between the metal and purlins to mitigate the concern I have?
Does the moisture even matter; or, will the airflow in the vented attic dry out any droplets that fall on the cellulose?
Do I need to buy the foil bubble insulation?
Thanks for your counsel.
-Mike
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答复
All metal roof manufacturers require an underlayment under the roof. The lowest cost is standard synthetic roofing underlayment. You can skip it but will eventually get some ceiling damage. It is hard to control where the drips happen, you might end up with a stop that will not dry enough over time, eventually saturating the insulation.
I can't find a temperature spec for typar but if it is rated for around 250F it should also work. Most house wraps tend to be very slippery so it might not be the best surface to walk on.
Thank you for the tip.
I contacted the Typar Principle Engineer about temperature limit of Typar and he responded:
“由于Typar是PP，因此最多可以处理260F。”
Question about diagonal 1x4s between house wrap and metal roof:
由于我不会有任何胶合板甲板，purlins上的对角线1x4会为排水平面和烟囱效应空气干燥途径提供任何有意义的目的吗？
I ask because I can saw up enough 1x4s in and hour if it serves any meaningful purpose. Just thought the airflow in the vented attic will flow by the underside of house wrap.
As to safety using house wrap on roof, I will take the extra care needed. Also, I will be working from eve and starting on a gable end, so I will not be standing on the house wrap over purlins. but rather standing ont he previous sheet of metal until the next panel is partially fastened.
Since it is over a vented attic, there is no need for additional ventilation. House wrap is has excellent permeability, any moisture above it will easily dry through the house wrap. I can't see the 1x4 doing much if anything in this case.
Just re-reading your reply it sounds like you won't have a roof deck. In this case the house wrap or any membrane type material won't work, the moisture will now just condense on the inside surface of the house wrap.
如果您想跳过屋顶甲板，我认为您最好的选择是羊毛材料。
麦克风，
Are you familiar with CondenStop? Haven't used it but it's used in the post frame field to address condensation under metal roofing without needing to add another product. You mentioned creating a conditioned shop with insulation above an OSB ceiling and for that this is not a good solution. This is a good solution when building an open framed metal roof. Just wanted to share since many are not aware it exists.
Condenstop是制造商将羊毛涂在金属面板的底面。羊毛吸收并存储冷凝水蒸气。在适当的温度和通风条件下，吸收的水将再次蒸发到环境空气。不想要芯吸的地方，您可以闪烁燃烧的羊毛。这通常是在建筑物外部进行的，例如覆盖门廊或屋檐的金属面板区域。
http://www.watsonmetalsllc.com/products-and-services/condenstop.php
https://fabral.com/post-frame/accessories/condenstop/
https://www.youtube.com/watch?v=fOHfBZf3im8
https://www.youtube.com/watch?v=yybuqqefs84
克里斯
Thanks Chris.
Ironically, of the three Watson Metals branches one is in my county and I have purchased materials from them for a few projects. I will stop in to inquire for my side shed roof.