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smallcabin
Member
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# Posted: 2 Dec 2015 03:01pm
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Ok...just curious to know what you guys think and/or would recommend?
I'm in the process of insulating the cabin now. My question is...Is it a good idea to add a vapor barrier to the fiberglass insulation? Idea behind this is that it will give a higher R value? Is this even necessary? My concern is that in doing so...would I risk molds development?
thanks!
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MtnDon
Member
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# Posted: 2 Dec 2015 03:04pm
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where are you? vapor barriers are good for some places, bad for others.
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DaveBell
Moderator
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# Posted: 2 Dec 2015 09:02pm
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Try this.
http://www.energyvanguard.com/blog-building-science-HERS-BPI/bid/75130/What-Happens-W hen-You-Put-a-Plastic-Vapor-Barrier-in-Your-Wall
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KinAlberta
Member
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# Posted: 12 Dec 2015 09:44am - Edited by: KinAlberta
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Off topic but are you set on fiberglass or would you consider rock wool or cellulose ?
You might want to read up on the other options. I was quite surprised about the benefits of cellulose. In my case I added loads of fibreglass to my home's attic only to then learn that fibreglass loses 50% of its value due to convection by -40, just when you need it the most.
More recently I used rock wool batts in my basement reno (interior ceilings, surrounding the furnace room, etc) and loved installing it.
If you go with Fiberglass batt, make sure you install it carefully so as not to leave any perimeter gaps. Again on my basement reno I had to reinstall all the batts due to the horrible 1970s install.
Here's a near random link. I googled bad Fiberglass batt install. Note it's comments on rock wool.
http://blog.lamidesign.com/2012/01/what-you-don-know-about-mineral-wool.html
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smallcabin
Member
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# Posted: 14 Dec 2015 02:16pm
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Quoting: MtnDon where are you? vapor barriers are good for some places, bad for others.
Don,
Wisconsin
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smallcabin
Member
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# Posted: 14 Dec 2015 02:19pm
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Quoting: KinAlberta Off topic but are you set on fiberglass or would you consider rock wool or cellulose ? You might want to read up on the other options. I was quite surprised about the benefits of cellulose. In my case I added loads of fibreglass to my home's attic only to then learn that fibreglass loses 50% of its value due to convection by -40, just when you need it the most. More recently I used rock wool batts in my basement reno (interior ceilings, surrounding the furnace room, etc) and loved installing it. If you go with Fiberglass batt, make sure you install it carefully so as not to leave any perimeter gaps. Again on my basement reno I had to reinstall all the batts due to the horrible 1970s install. Here's a near random link. I googled bad Fiberglass batt install. Note it's comments on rock wool.
Thanks Kin,
unfortunately, fiberglass is what i've purchased and will be using.
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smallcabin
Member
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# Posted: 14 Dec 2015 02:25pm
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Davebell,
thanks! very informative info.
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Steve961
Member
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# Posted: 14 Dec 2015 02:41pm
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I live in Wisconsin, and my small cabin is in north central Wisconsin. Unfortunately, your question doesn't have an easy yes or no answer. A lot depends on what type of sheathing, exterior insulation, building wrap, and even siding you have. Moisture that finds its way into a wall cavity, and eventually it will, needs a way out. If you have an impermeable vapor barrier on the inside, and an impermeable barrier (i.e. sheathing, foam boards, etc.) on the outside, moisture will not have a way to escape.
When I was building my cabin I found this article which was a great help to me in understanding wall construction and moisture control:
Building Science Corporation - Mind the Gap, Eh!
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Steve_S
Member
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# Posted: 14 Dec 2015 05:28pm
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Quoting: KinAlberta http://blog.lamidesign.com/2012/01/what-you-don-know-about-mineral-wool.html
Darn good article and well summed up. Should be a mandatory read for anyone building a place today. I would have used Rockwool (ala Roxul) had I not got such amazing deals on ISO & XPS.
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smallcabin
Member
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# Posted: 15 Dec 2015 05:55pm - Edited by: smallcabin
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Steve961,
thanks for the article. Very helpful! So what did you end up using for insulation? Care to share some pics/advice?
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Steve961
Member
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# Posted: 15 Dec 2015 07:49pm
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Quoting: smallcabin Steve961, thanks for the article. Very helpful! So what did you end up using for insulation? Care to share some pics/advice?
My insulation needs ended up being quite different than most since I used shipping containers for the majority of my structure. I used 2" of closed cell spray foam insulation on both the container walls and the standard frame walls in the container openings. 2" of spray foam has the added advantage of being its own vapor barrier. And while I think spray foam is an excellent insulation, there are more cost effective options for traditional construction.
If I were to build another frame building, and I'm seriously thinking about adding a small bunk house this summer, I would give serious consideration to "The Perfect Wall" concept (link below).
The Perfect Wall
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Steve_S
Member
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# Posted: 16 Dec 2015 09:32am
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I'm going with a hybrid "Perfect Wall" mostly due to the materials I was able to collect. Below is a diagram of my wall structure.
2x6 walls @ 24oc:
Between studs: 5-1/4" Insulation Panel which has 1/2" Bonded treated fibre on each face with high density EPS Foam in between. This stuff has an R22 insulation value.
1/2 OSB sheathing on the exterior, covered with Tyvek, then 2" paper faced ISO (R10), covered again with Tyvek, Horizontal strapping, to be finished with Vertical Board on Board rough cut presenting an 8" face. This allows for an active 6" air channel flowing up and air space provided by the strapping so none of the board is actually directly against the exterior wall insulation.
The Tyvek I am using on the walls is the breathable variety which sheds water...
My Hybrid "Perfect Wall" Design
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Julie2Oregon
Member
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# Posted: 16 Dec 2015 12:03pm
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So you're basically making your own SIPS panels then, yeah?
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