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!


4 Answers

Best system for foundation waterproofing and insulating

Local contractors in central OH (zone 5) are either applying a product such as Delta MS (dimpled mat) outside of the poured wall foundation for waterproofing and then applying blanket insulation on the inside of the wall in the basement ... their thought being that once wet, the R-value of an exterior insulating product is severely reduced. Others are applying a damp proofing membrane such as Tremco Tuff-N-Dri to the exterior of the poured wall foundation followed by Tremco's Warm-N-Dri 2 3/8" R-10 foundation board (rigid fiberglass product). Which is the better method?

In Energy efficiency and durability | Asked By Milan Jurich | Jan 14 12
4 Answers

How to choose the right replacement windows

I have two very large windows on the south side of my house, 1-98"x72" and 1-121"x72". Both windows are covered by overhang porches but do have sun directly on them certain times of the year. I live in central Oklahoma where it gets really hot in the summer and fairly cold in the winter. I have found some replacement windows that have a u factor:0.31 and a shgc: 0.28 and I am needing to know if this is the best choice for the region I live in. I would appreciate any and all help, thanks.

In General questions | Asked By stuart Osborn | Jan 14 12
5 Answers

HRVs tied into Forced Air Systems

My understanding is that HRVs should have dedicated ductwork sized specifically for lower ventilation flows. The system should also be balanced and commissioned.

In Mechanicals | Asked By j chesnut | Jan 14 12
10 Answers

Correcting a thermal bridge

I'm building a house in zone 6a, Central NH. My plan is to wrap the house with 2 layers of eps totaling 4.5 inches with the joints staggered. The framing is 2x4 and no interior vapor barrier will be used. I was planning to add 3.5" of fiberglass to the cavities.I'm using DuPont drainwrap over OSB with the joints and stud lines taped with zip tape. The foam will be furred vertically with 3/4" boards to ventilate behind the siding.

In Energy efficiency and durability | Asked By Nate Weiner | Jan 13 12
5 Answers

Jevons' Paradox debunked

We provide new statistical evidence to show that energy efficiency policies and programs can reliably cut energy use—a finding that is consistent with the policy stance of leading experts and organizations like the US Energy Information Agency (EIA) and the World Bank. (link)

In Energy efficiency and durability | Asked By Andrew Henry | Jan 12 12
1 Answer

Does moisture get trapped in the roof insulation?

I read the building science insight "Leiningen Versus The Ants Redux" by Joseph W. Lstiburek with great interest. I plan to build a workshop in upstate NY (zone 5+) using a similar approach. This seems very similar to the PERSIST method discussed in Martin Holladay's article "Getting Insulation Out of Your Walls and Ceilings".

But the details are tricky, as Joe learned with his barn. In Figure 1, Joe shows fully adhered membrane on top of the under-roof sheathing, on top of the roof insulation, and on top of the over-roof sheathing.

In Energy efficiency and durability | Asked By Clement B. Edgar III | Jan 13 12
2 Answers

Advice on proposed zone 6 wall assembly

We are building a cape in zone 6, Waldoboro Maine. I am considering the following wall assembly and have several questions regarding the components. Forgive the length of this, but I don't know how to make this any briefer.

In GBA Pro help | Asked By tom ruben | Jan 13 12
4 Answers

Existing brick veneer wall Zone 4A

What is the effective strategy for increasing the R-value for an existing brick veneer wall over 1" airspace over 1/2" fiberboard sheathing(w/o WRB) over 2x4 studs with old not full depth fiberglass insulation between and plaster over gypsum lath finish? Given the generally excellent condition of the interior plaster I am unwilling to remove and re-insulate. Can a spray foam be used in the airspace injected from the exterior?

In Energy efficiency and durability | Asked By Peter Anderson | Jan 12 12
10 Answers

The Real Problem of Subsidies

This is a clip from the following site;

http://theenergygame.blogspot.com/2011/11/we-need-to-feel-pain.html

The Real Problem of Subsidies

In Energy efficiency and durability | Asked By aj builder, Upstate NY Zone 6a | Jan 11 12
4 Answers

Spray foam roof insulation questions

In a recently completed home of our design, the contractor - a firm I'd not worked with before - convinced the client to use spray foam insulation for walls and roof instead of the cellulose I'd planned. Part of his justification for accepting lower-than-code R-value of the roof was that the Delta-T of a sprayed roof deck assembly would be lower than if the insulation were at ceiling level. He noted that the air temperature of a vented attic would be some 30° higher than outdoor air.

In Energy efficiency and durability | Asked By James Morgan | Jan 13 12
Register for a free account and join the conversation


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