Q&A: A Forum for Green Building Experts and Beginners

[Click map to enlarge]

Please register for a free account or sign in to ask and answer green building questions.

The usual rules of courtesy apply:
1. Be nice.
2. If you can't be nice, be polite.
3. If you can't be nice or polite — well, please be brief.

To attach a photo or illustration:
Under the box labeled "More explanation," look for the words "File attachments."
Click that, and you should be able to attach a photo.

Thanks for joining the conversation!

19 Answers

"Study group" - resilient design.

I have been thinking about the "pretty good house" (PGH) concept lately and also about "resilient design".

I find it helpful to think of resilient design in terms of "risk management".
From a risk management perspective, much of what is already considered in the design process can be called "resilient design"...
For example, bulk water intrusion into an assembly represents an identified risk that many designers mitigate by specifying appropriate flashing details.

From a risk management perspective then, "resilient design" isn't something new that needs to be considered...

In Energy efficiency and durability | Asked By Lucas Durand - 7A | Mar 16 12
7 Answers

Follow-up to Spencer Burnfield's question of 13 March: Closed vs. Vented Crawls in the Pacific Northwest.

I'm still conflicted about closed crawls in the Zone 4 Marine climate of the PNW. Studies done by Washington State U. have shown that vented crawls "work" in this climate: i.e., they don't cause the problems they cause elsewhere. Also, closed crawls allegedly exact a small energy penalty. Several local building experts have thumbed their noses at the East Coast "fad" for closed crawls. "The more vents the better," one says.

To me, though, something doesn't "work" just because it isn't quite as bad as it is in other climates. I still don't see the point of open crawlspaces.

In Green building techniques | Asked By Gordon Taylor | Mar 18 12
3 Answers

Does additional air sealing improve performance linearly or exponentially?

I just had two energy audits done on my 1959 walk out ranch: one throgh the utility company's program for $50 and one through an independent company for free. I wanted to see how the two compared so I could better advise my clients. The independant company was more enthusiastic about air sealing, but of course this also makes for a better sales pitch.

In Energy efficiency and durability | Asked By Hallie Bowie | Mar 19 12
10 Answers

Moisture problems with Vapor Barrier - Part 2 - Another question

A follow-up question:
Is there a problem having paper backed insulation and a plastic vapor barrier on walls and ceiling? When I observed moisture problems it was not condensed on the paper or plastic, but on the coldest surface i.e. the roof sheathing and Styrofoam air ducts. Some have said the plastic is the problem and the walls/ceiling need to breathe while my architect says install the plastic for air seal and thermal efficiency. Confused! What's correct?

In GBA Pro help | Asked By Tony Moore | Mar 18 12
7 Answers

Where to place the vapor barrier in a concrete slab on grade with radiant floor and integral colored concrete?

We are building a 2,200-sq.- ft. single-story concrete slab-on-grade home with hydronic floors throughout and will be integrally coloring the concrete. Stem walls will be poured and then interior slab will be poured. We are installing hydronic PEX directly to the XPS foam, which will be taped, and then placing rebar on chairs above the PEX. The slab will be 5 inches thick with fibermesh such as Stealth 150.

In GBA Pro help | Asked By A Lalande | Mar 18 12
2 Answers

My walls are cold and have inadaquate insulation. Spray foam options?

I'm looking to make my house more comfortable and I'm not quite ready for new siding yet. My current siding is old and will need replaced in the next 5 years or so but I want to wait and do the windows at the same time. I will have foamboard insulation put up under the new siding. In the meantime, my walls are cold and drafty despite my house being air-sealed and the attic insulated really well (Iowa, R-60). Would open cell spray foam be a good option? I have an old house but I have drywall so I presume there's a vapor barrier in the wall (I don't know that for certain however).

In General questions | Asked By Jason Schaffer | Mar 18 12
4 Answers

Moisture problems with vapor barrier - Part 1

I am a home owner building a 2,000 sq ft addition to our home 50 mls. north of NYC, on a small mountain in the Hudson Valley, so it's colder up here in the winter and less humid than the river valley in the summer. This is a wood frame two story structure without central AC built on an exposed concrete slab floor. We are at finished rough-in stage. This winter, the radiant heat in the slab was first turned on, resulting in a lot of moisture being evaporated from the concrete into the building.

In GBA Pro help | Asked By Tony Moore | Mar 18 12
3 Answers

Potential Difficulties with Roof Design

We are in the final design phase of our super insulated home and need some advice. The difficulty is with the eastern side of the house(entrance way) keeping in mind that an in-law apt. will be added in the future. The two final designs are attached. One with a flat roof porch and one with a high porch roof with beam supports.
The Problem: We prefer the high roof design but have concerns in two areas:

In General questions | Asked By rebecca Surprenant | Mar 18 12
12 Answers

I live in Northern Virginia. I am trying to resolve a dispute between my insulation contractor and the city engineer.

I plan on having open cell spray foam installed in the rafters of the top level of my home.

Dispute Details:
- The city engineer stated that I need to install a ridge vent and baffles that run the entire length of the roof from the ridge vent to the soffit vents. Then once inspected and approved, I can have the spray foam contractor spray the insulation over the baffles.

- The Contractor states that the engineer does not understand the technology and the the
spray foam should go directly against the sheathing.

In Building Code Questions | Asked By John Horton | Mar 15 12
22 Answers

Building a fixed-pane window into foam

I'm spinning this off from one of the many triple-pane threads rather than derailing it with my question.

Keith Gustafson wrote:

They get better:
I believe that the 1 1/8 triples are their thickest standard, as they did not want to go higher.As it is the ones that I selected end up with a U of .13, [R 7.7] COG.

In General questions | Asked By Minneapolis Disaster, 6B | Sep 24 11
Register for a free account and join the conversation

Get a free account and join the conversation!
Become a GBA PRO!