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21 Answers

Community insights for a straw & steel green build?

We are building a straw-bale house with steel bones in Sacramento, CA in spring 2015 and I'd love to get some insights from the community! We are pretty far along into the design process, but with nothing purchased as of yet I'd love to get some input before we put our money where our mouths are.

Our goal is to have a (mostly) passively heated and cooled home in (relativity) temperate Sacramento, CA. Passivhaus would be nice but it's an aspiration rather than a goal. Our lot has a number of trees for shade that we plan to utilize, especially in the western aspect.

In Plans Review | Asked By Nick Campbell | Aug 26 14
3 Answers

Closed-cell spray foam vs. high density batts

We're currently in the planning/permitting phases of a new home in the Southeast. We've hired a green building specialist to give us some specific recommendations and model our home to give us an approximate hers rating. He has advised that we use high density fiberglass batts in our mostly cathederalized ceilings upstairs. Our contractor (traditional) has recommended closed cell spray foam because he thinks it will help with the structure and have less air permeability. There's a definite cost difference. Please help steer us in the right direction.

In Energy efficiency and durability | Asked By Megan Wood | Jul 11 15
7 Answers

Interior T&G pine with rigid foam exterior insulation

Hi all,

In Energy efficiency and durability | Asked By Adam Emter | Jun 9 15
5 Answers

Are airtight homes causing indoor air quality problems?

In the quest to conserve energy by making the homes so air tight the quality of the air inside the home has gotten worse.

In General questions | Asked By Jack Lofstrom | Jul 15 15
16 Answers

Slag & fly ash geopolymer?

The father of geo polymers, Joseph Davidovits, has proposed a standard geo-polymer cement that uses fly ash, blast furnace slag and a "user friendly" alkali activator to make a cement. It' sets at room temperature in several hours and develops outstanding strength quickly.(7000+PSI @ 28 days). Without additional aggregates it is about 2.8/ inch. Since it uses about 90% waste materials it is quite "green". With that kind of insulating structural concrete far less plastic foam would be needed, a typical basement floor would be r10 by itself.

In Green building techniques | Asked By Jerry Liebler | Mar 16 15
21 Answers

Foundation capillary break & waterproofing

My wife and I are building a small home (First Day Cottage) on a full foundation with a walkout on the downhill end. I read about having a capillary break between the footing and foundation wall and it makes sense to me. When I asked the concrete contractor about it he said he's never done it (though he did remember one other customer who asked about it a couple years back). I get the impression they won't leave me much time to do it myself between pours.

In General questions | Asked By Martin Frank | Jun 30 15
5 Answers

Eave vent detail

Hi GBA
Does anyone have a link to an eave/rake vent detail where:
cold climate
gable roof
metal roofing
cathedral ceiling
minimal overhang
board&batten siding
rain screen

I have colleagues citing anecdotal evidence saying with an airtight envelope, the need for balanced roof venting is not critical, i.e., continuous eave vent and no ridge vent is sufficient.

Thanks

In General questions | Asked By Erik Olofsson | Jul 16 15
3 Answers

Revisit: Insulating a wall from the outside — but for a 200-year-old home

I stumbled upon a question from a fellow who wanted to insulate his walls from the outside and add more foam board too. This intrigued me as it was inline with my thoughts on a similar project. The problem was, I could not ascertain from the feedback whether it applied well to my situation.

So, I wanted to throw the question out there.

In General questions | Asked By Les Newsom | Jul 16 15
1 Answer

Polyethylene or peel-and-stick membrane?

I am working on a cathedral ceiling with exposed rafters. (Rafters, Tongue and groove, 5/8 plywood, 6" of polyiso, 1/2 OSB, underlayment and metal roof).
I have available a 10 mil' polyethylene roll that would cover the entire roof area in one piece. Is this an acceptable method for air sealing the system? I know this material doesn't have the advantage of "self healing" around fasteners. Would that be a concern?
I am in Austin, Tx.
Thanks

In Energy efficiency and durability | Asked By Harold Orozco | Jul 17 15
2 Answers

"Designing for Durability"

Martin and others: I just read the article in Fine Homebuilding ( September 2015, #253) on the new HUD guide for building a durable house. I do not understand the "overhang ratios" given in the chart on p. 58., and am wondering if they have made an error. On a 9' wall( single story house) the 0.5 ratio required to get excellent protection in a "Damp" or "Wet" climate means an overhang of 54" . That's one hell of an overhang!

In Energy efficiency and durability | Asked By KEVIN ZORSKI | Jul 16 15
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