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1 Answer

I'm getting ready to build a home near Indianapolis, Indiana, and I've been referring to the Building Science material for guidance on best practices for construction. When I look through the Building Profile for a Mixed-Humid Climate: Louisville it mentions the use of rigid insulation sheathing. It also notes that in mixed-humid climates (like Indianapolis), roof and wall assemblies are best designed to dry to both the exterior and interior, but the is not always possible when rigid exterior insulating sheathings are used.

Asked By Tyson Clemmer | Aug 17 14
8 Answers

We had our final blower door test and it wasn't what we had hoped. Our initial cfm50 was 98 with windows and door and all the sheathing done so I expected a substantially better result with insulation and the smart vapor barrier. Our result was 220.

Obviously the higher air leakage has to be from penetrations after the building envelope was finished - vents mostly, I figure.

Asked By Lucy Foxworth | Aug 14 14
6 Answers

Someone in my area which is located in a zone 5 recently built a small house and sandwiched used 2.5" polyiso between the studs and the exterior wall sheathing. At first I was skeptical but still intrigued. It certainly simplifies window details compared to foam on the exterior. However I guess you would loose some structural rigidity. But would you really loose that much? If the wall sheathing is screwed on over the foam, the friction of the foam against the studs alone should help keep the wall from racking.

Asked By Dillon Vautrin | Aug 14 14
2 Answers

Finally am at the point of redoing my attached Ell roof on my 200+ year old colonial.
This is what I currently have.
Zone 5

Inside 3/4 inch pine (obviously very air leaky) cathedral ceiling, Behind that it appears to be a foil faced fiberglass. Prior owner did this some time in the 80's. The sheathing is 1 x 10 running from peak to soffit ( again very leaky). There are 2 layers of asphalt shingles, then a 1 inch layer of Styrofoam insulation board with another layer of asphalt on top of that. Fun Fun!

Asked By terry grube | Aug 14 14
3 Answers

My roof (zone 3B) needs insulation, but between Martin's concerns and the inexperience of the contractors in this market, I am conceding that 5" of polyiso foam isn't going to happen. I think that 3.0" nail base (R15) can though (with taped seams). I'd like to get closer to the code minimum of R30 for the assembly. I would rather not tear out the finished interior vaulted ceiling (cedar shingles on battens on felt paper, I know, strange), but the lousy interior air barrier (i.e. the felt paper) concerns me.

Asked By Keith Richtman | Aug 14 14
4 Answers

How are those of you using this product detailing the bottom of the wall where the Roxul is exposed?

I noticed on one post about a project in BC, they used a perforated galvanized channel to encase the bottom of the IS. Does anyone know where to source a channel like that?

I'll be using 3" Comfort board over 1/2 CDX sheathing, over 3/4" x 3" furring strips, then cedar shingles.


Asked By Edward Krause | Aug 8 14
2 Answers

The main question is whether the air space provided by the metal ribs would provide adequate air flow. If not, how about vertical 2X 'purlins', forming site-built insulation baffles that would be insect screened at both ends?

Asked By Michael Roland | Aug 7 14
10 Answers

We are meeting a lot of resistance from local concrete contractors & structural engineers when we tell them that we want a capillary break between the footing and the foundation wall. Are there any documented cases of this capillary action being a source of moisture/ mold / finish material problems? Are there any scientific studies that compare the moisture levels in foundations walls with and without a capillary break? The capillary break makes sense to me intuitively, but nobody wants to pay for it or change their ways unless we can show them proof that it is necessary.

Asked By Eric Stear | Jul 31 14
2 Answers

We are building a tiny house currently with cathedral ceilings and 2x6 rafters. I have access to large quantities of rigid foam and would like to make use of it. Can I fill the rafter spaces with layers of rigid foam and spray can foam the seams and cracks of each layer as an air barrier and keep the roof unvented? I would then like to add another layer of rigid under the rafters with taped seams to prevent thermal bridging and air leakage once again. Then I would strap under that so I could still install T&G on the ceiling.

Asked By jordan Saunders | Aug 5 14
2 Answers

Climate Zone 6B

Asked By JMS Build | Jul 30 14
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