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5 Answers

How can I best install rigid foam as I finish my attic?

Hi folks,

I'm finishing off my attic. The plan is to use fiberglass between the old true 2x6 rafters, which will be vented with baffles. I then want to put lots of rigid foam on top of the rafters, as I'm in a cold climate in upstate New York. I'm thinking 4 inches.

How can I find screws to long enough to fasten the furring strips through the foam to the rafters?

Will the foil-faced foam act as an adequate vapor-barrier as long as I seal the seams with aluminum tape?

Need I use any special drywall on top for adequate fire protection?


In Green building techniques | Asked By J Stair | Oct 19 12
27 Answers

Rainscreen Roof?

I've seen lots of info about rainscreen walls, what about roofs? I'm planing on using a standing seam metal roof, 10/12 pitch. Should I be considering rainscreen details for this?

In General questions | Asked By Eric Mikkelsen | Oct 13 12
3 Answers

What are the pros and cons of pouring concrete in an existing crawl space, and how thick should it be?

I admit I am a bit of neat freak, but the idea of have a nice concrete floor in the crawl space appeals to me.

This is a spacious crawl space: 20x24 feet and nearly 6 feet tall. It houses the propane furnace and the electric water heater.

The walls I believe are concrete black. The floor is currently stone and dirt above a white plastic sheet which shows through in a few places. The crawl space opens to a smaller basement below it.

I believe the crawl space s currently vented to the outside (a couple of small, probably ineffective vents), and I am also considering sealing it.

In Green building techniques | Asked By Moya Mim | Oct 18 12
4 Answers

Spray foam basement ceiling to block moisture and improve efficiency?

Upstate NY--The homeowner bought a home not realizing that it was in a flood plain. Over the last 5 years the basement and crawl space have flooded up to the rim twice, taking out the boiler and water heater, which have been moved upstairs. When it's not flooded, the basement + crawl have high moisture levels which is causing mold upstairs as well. We've been asked to fix moisture and improve efficiency. Ideally, we'd raise the building three feet, but the money isn't there.

Here's the question: can we spray foam the basement rim and ceiling and install an HRV upstairs?

In Energy efficiency and durability | Asked By Bennett Sandler | Oct 17 12
7 Answers

What is a cathedral ceiling?

In reading about insulation I see recommendations about cathedral ceiling vs other types.

What exactly is a cathedral ceiling, and specifically is the ceiling in a an attic considered a catheral ceiling?

In this particular attic, the ceiling is somewhat high in the middle of the attic (maybe 9 feet), but slopes down to height of zero at the edges. It's your basic upside upside down V.

In Energy efficiency and durability | Asked By Moya Mim | Oct 18 12
4 Answers

Is it advisable for propane furnace to have an exterior air intake for combustion?

The propane furnace is located in crawl space, which is also open to the basement.

I was considering Martin's advice to seal up the crawl space and it occurred to me that might be an issue for the propane furnace, which currently does not have an air intake for combustion. (This is a water based furnace so come that is the only reason for air intake).

Come to think of it, even if the crawl space remains vented, shouldn't the propane furnace be drawing air from the outside?

In Mechanicals | Asked By Moya Mim | Oct 18 12
5 Answers

Vented Cathedral Ceiling — Affordable Insulation

About a year ago, when i moved in to our new (old) home in Montreal. I had an energy audit done that really highlighted the piss poor job of insulation the previous owners had done with their attic conversion.

In Energy efficiency and durability | Asked By Aaron Laudi | Oct 17 12
12 Answers

Should I use closed-cell foam to replace rodent-ruined insulation?

20-year old house has uninsulated basement (both a crawl space and a concrete part) and attic.

There is insulation in the ceiling of the basement of the type that you roll out, as well as the floor of the attic.

The insulation has been ruined by rodents.

It seemed that replacing the ruined insulation with 3" of closed cell foam that would be clean and rodent-resistant would be an easy choice. But I want to make sure there are no serious drawbacks.

-Besides price, are there any drawbacks to properly installed closed cell foam?

In Energy efficiency and durability | Asked By Moya Mim | Oct 15 12
4 Answers

Is closed-cell spray foam fire resistant or does it spread fire?

I was surprised to hear that closed cell spray foam if installed in basement has to either have (i) special paint coating to slow down the spread of fire or (ii) sheet rock over it.

Is this a true? Is this an advantage of open cell spray foam, in that it is much more fire resistant?

In Energy efficiency and durability | Asked By Moya Mim | Oct 18 12
3 Answers

IBC Airtightness conversion

How do you convert cfm/sq. ft. @ 75 Pa to ACH 50?


In Building Code Questions | Asked By Roger Lin | Oct 17 12
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