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3 Answers

Open-cell foam and airtightness

I've seen reports from the foam manufacturers touting how much better the foam is than fiberglass of the same R value. They're essentially using the improved airtightness of the foam to show better performance compared to fiberglass with no air barrier. I can see it's mostly BS. I am wondering if you have a proper air barrier if open cell foam can measurably increase the air tightness of the structure?

Asked By Brad H | Jul 25 16
6 Answers

Preferred underlayment under metal on unvented roof?

Hi Everyone,
Need to make a final decision on which underlayment to use under a metal roof on an unvented roof system. The roof is currently built as follows: Beams on 5' centers; 1 1/2' T&G decking; 3/8" plywood diaphragm - seams taped; with TriBuilt granulated self adhering underlayment on top of the plywood.

Next I'll be screwing down 5 1/2"RayCore SIPS panels over heated space and framing boxes over the eaves covering everything with 5/8" CDX. Still looking at metal roof products but am zeroing in on a high seam (1 3/4") snap lock system. Roof pitch is 2/12.

Asked By Robert McKee | Jul 23 16
4 Answers

Storage space in attic vs. living area

Hi.

I have an old, leaky house and dream of a new energy efficient home of about the same size (1200 sf). Right now we use the attic and knee walls for storage. From what I have read, it is no longer considered energy wise to use attics in new homes. But, if we loss that space (and won't have knee walls), we will have to build more square footage to accommodate our stuff. That does not seem particularly green. Please advise.

Asked By Jen Weaver | Jul 24 16
9 Answers

We are building a 700-sq.-ft. cottage on southern Vancouver Island, Zone 4 Marine

The plan is to use 4 inches polyisocyanurate - R22.6 - (glass fiber covering) exterior insulation no sheathing except for earthquake walls. No insulation in the 2x4 wall cavities, tyvek on the exterior of the foam and vapor barrier between the polyiso and the framing. ls this ok or will we have problems. We have to present our wall assembly plans to the city and the city wants a vapor barrier but we are not sure if this is necessary.
Sandra Garraway

Asked By Sandra Garraway | Jul 22 16
9 Answers

Will positive pressure work to vent an attic (i.e., blowing air in)? Attics exhaust fans are a bad idea. But what about blowing air in (using positive pressure).

My father is interested in removing heat from his attic to try to keep the upstairs of his house somewhat cooler. I have advised him that generally speaking, attic fans are a bad idea, which he has come to terms with. However, with that understanding that creating negative pressure in the attic can cause all kinds of problems (sucking out air from the conditioned space, possible back-drafting of combustion appliances, etc.), he has come up with the idea to blow air into the attic instead (i.e., creating positive pressure) to force the hot air out.

Asked By Erica Downs | Aug 12 12
14 Answers

Unvented cathedral ceiling — insulating from above

I am re-doing my family room roof, which is a cathedral ceiling.

Since the roof is being re-shingled, I thought it a good time to remove the sheathing and lay down some closed cell foam. I have some unopened from a previous project

Everything I've read about unvented Cathedral ceilings talk about them drying from the inside. Obviously this can't happen if I'm spray in the closed cell foam onto the dry wall ceiling from above

The ceiling is 8" from drywall to plywood

Asked By Paul Buchkowski | Jun 25 16
1 Answer

Ads on GBA prime

Over the last week I've noticed the appearance of advertisement on GBA prime. Is this due to a technical problem or is it the result of a change in vision?

My decision to join GBA prime was motivated by the fact that it would be free of ads. I'm sorry to say that if this is the direction that Taunton Press wishes to follow, that once my membership runs its course that I will regrettably not be renewing.

Asked By Marc Labrie | Jul 23 16
0 Answers

I have a 1950 brick clad house and want to improve the wall insulation.

There is an air gap between the brick and the sheathing (shiplap) but no weep holes are apparent at the top or the bottom. In most place the brick appears to be sitting on the concrete foundation in a bed of mortar. In some areas there is a strip of what appears to be metal between the brick and the foundation. The lone area where the interior wall has been opened has about an inch to an inch and a half of faced fiberglass - facing is to the interior. There is extensive overhang with the roof.

Asked By Andrea Quimby | Jul 23 16
20 Answers

Ramblings on thermal mass, AC and window fans

This is isn't really a specific question so feel free to offer random thoughts

Asked By Alan B | Jul 10 16
15 Answers

Fluid WRB at big box stores?

Hello,

I am interested in building a workshop/studio 16'x12'x12' and am interested in using a WRB. I read the wrb in a can article on this website and lots of other information on the subject. When I look at the mentioned products, they do not seem to be accessible in local stores or something that a non-contract professional can find. Is there a Home Depot or Lowes type solution? This studio will be assembled in the order of a 2x4 framed, OSB sheathed, fluid WRB, drain wrap, 3" XPS and seam sealed, rainscreen, fiber cement.

Asked By John Haller | Jul 21 16
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