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46 Answers

Unvented slanted roof with radiant cooling and NO polyurethane in 4C

We are in Everett WA, north of Seattle, right on the coast, zone 4C. I hope that our location will save us...
We have a low sloping steel, west facing roof. Double, 30 weight felt paper underneath to dampen rain noise. I presume 1/2" plywood sheathing. 2x12" rafters, 11" true depth.
We will install WarmBoard R (13/16" thick OSB with aluminum tracks) underneath the rafters for summer cooling and supplemental heating in winter.

Asked By Jan Verschuren | Mar 11 15
23 Answers

Insulating wood I-joists with Roxul

O.K., to repeat, I'm building a 1-story house in Zone 4C. Builder is using wood I-joists 16" O.C. for the floor. After considerable thought and reading, including comments by Dana Dorsett and research by Washington State University, I decided that an open crawl space would work for me. However, I have insisted that we use good insulation: R-24 (commercial size) stone wool batts by Roxul for the floor insulation. This comes in 16.25" widths. My builder says, Fine, but how are we going to shove them past the flanges at the top of the I-joist so that they're snug against the floor?

Asked By Gordon Taylor | Nov 21 13
5 Answers

Exterior foil-faced polyiso question

I live in the San Francisco Bay Area and my application is as follows:

Plywood – sealing all plywood seams with Signa Wigluv – 2 layers of ¾” foil faced polyiso (all seams taped) – WRB – Rainscreen – Fiber cement siding:

The plywood is serving as my primary air barrier. I understand that any moisture that gets behind the first layer of polyiso (between the ployiso and plywood ) will dry to the inside and any moisture that gets on the outer layer of polyiso will dry to the outside.

My question relates to the area between the two layers of foil faced polyiso.

Asked By Randy Mason | Mar 16 15
8 Answers

Converting old outbuilding to heated workshop

I have a wooden garage, built in 1929 in coastal Maine, in remarkably good shape. It's got a post and pier foundation and had the front ripped off to convert to a 2 car garage in the 90's. I plan to reconvert it to it's original intent as a workspace. Like most of these old outbuildings in our neighborhood, the lawn has grown up to the base of the siding (or maybe they were intended that way) and there is a major negative grade inside, kind of like an earthen crawlspace foundation. When I started digging around and found this out, I got very worried about rot.

Asked By A. Bradford | Mar 20 15
2 Answers

Should I air seal and insulate above the ceiling of my attached garage?

My house has an attached garage. The attic spaces above the house and the garage are not separated; there is no wall between them in the attic--it's all just one big attic. I am currently having the part of the attic over the conditioned space air-sealed and insulated. Should I additionally air-seal and insulate the ceiling above the attached garage? Even though it's not conditioned space? There is a water heater in there FWIW, and the garage does get cold in winter and hot in summer.

Asked By Nathaniel G | Mar 30 15
1 Answer

Two questions: Rigid foam in attic space

1. I have some knob and tube wiring running about 3 inches above the 1st floor ceiling, behind a kneewall. After having an electrician look at it I'm going to box it in with plywood, leaving a good size air gap. This will decrease the R value for this area. Is it ok to put 1 inch rigid foam on top of the plywood? This would make from bottom up: 1st floor ceiling, wiring with air gap, 1/2 plywood, rigid foam, cellulose, open attic and then roof.

Asked By Jeremy M | Mar 30 15
7 Answers

New home buyer — metal roof in Maine with no sheathing

Hello all,

I am a first time home buyer and looking into buying a new home. My wife and I have found the perfect home here in Maine, but found out today that the metal roof was attached directly to the perlins. I know typically there is supposed to be sheathing and a vapor barrier in between. I have found information on both sides of the argument, which have led me here. Is no sheathing adequate? How will it affect my energy use? and will it be a condensation issue? Is this ok for a cold climate here in Maine?

Asked By dimitrios maniatakos | Mar 28 15
5 Answers

Review of insulation/air sealing retrofit plan...

For a cathedral ceiling, still a popular subject of concern I see. I have gotten advice before and used this site to increase my understanding of many building issues. The ceiling currently, from the inside, has V-groove pine boards, then a 12" kraft faced fiberglass batt, no air sealing. There is a vent channel above the fiberglass of unknown thickness and quality (I ran into the builder and asked if it was 2", and he replied "probably less"). The decking is 3/4" OSB, asphalt shingles above (now at 25 years).

Asked By Howard Gentler | Mar 28 15
5 Answers

Old house, wet brick

The picture pretty much says it all. We had terrible ice damming this year, as did just about everyone in my area; houses both old and new saw wet walls and rainy windows for the first time ever. My house was built in 1850, and I have to imagine this has been a problem before. But this was our first full winter here. I'll try to explain the situation as best I can:

Asked By Chris Ermides | Mar 26 15
10 Answers

Interior plywood for earthquake areas — can it replace a vapor retarder?

We are renovating a 1925 Pacific Northwest house, Everett WA, right on the coast. It is earthquake territory here. So it would be good to keep this house up through any quakes we may get, when it can be relatively easily done. We have double studded the kitchen wall now. Making it 8" deep. The north wall became 9" deep. Now we are in low need of any vapor retarder for our climate I understand, zone 4C. Interior air barrier never hurts BUT, and here is my question... Would interior plywood sheathing be a good choice to replace the air barrier, caulking the seams.

Asked By Jan Verschuren | Mar 29 15
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