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!

23 Answers

Building an A-frame in Upper Michigan

We are planning to build a 1250 sq. foot A-frame. The problem is the roof as the inspector is requiring R-49. We know we want it to be well insulated. But due to the roof actually being the walls also...insulating space is an issue. We have already decided to to 2x 12 rafters with 2 inch ridgid on the outside for the roof. Walls are to be 2x4 with again 2 inch ridgid foam on the outside. Has anyone used Protex? Also does anyone one know where to get reclaimed 2" inch foam in this area?

In General questions | Asked By maureen mcginnis | Dec 25 11
5 Answers

How durable is silicone as the sole air tight gasket and adhesive for timber stud frame connections?

A supplier here in Ireland advocates the use of timber-framed walls using timber studs and insulation between 2 layers of plywood WITHOUT using any tapes or other adhesives to air seal the junctions..

The large prefabricated frames consist of plywood as the air barrier and silicone is used as the air gasket / adhesive squeezed between studs and plywood.

I have misgivings but is silicone used this way a durable and effective alternative to traditional fixing methods with tape at plywood junctions?

In Energy efficiency and durability | Asked By Tim O Brien | Jan 11 12
2 Answers

What is the best type of rigid foam to use and how do I ensure I am not trapping moisture in the wall?

I read your article on your website "Calculating Minimum Thickness of Rigid Foam Sheating" and viewed the rigid foam installation video on YouTube with David Joyce. Thank you for having a great website and videos with lots of information.

In Energy efficiency and durability | Asked By Owen Nelsen | Jan 12 12
12 Answers

Is make-up air req'd for a Conditoned basement heat pump water heater vented to the outside?


I have a tight house (2.0ach50p) and want to install a heat pump water heater in the heated basement. I have no back draft appliances and the house is all electric with a fully ducted HRV system. I occasionally run the range top fan on low and a bath fan for 15 minutes or less (timer switch).

In Energy efficiency and durability | Asked By Frank O | Jan 10 12
3 Answers

Re-roof Question

This Zone 5, coastal roof is leaking and going to be replaced via a low-interest, deferred HUD loan. (See photos). I had dreams of a Deep Energy Retrofit, but even with generous incentives from the electric utility, the expense is too great for the loan recipient, and a VERY incremental approach is required.

In Energy efficiency and durability | Asked By John Rockwell | Jan 11 12
2 Answers

Seal or Vent Bottom of Balloon-Framed Wall?

I am replacing the water table and belly band on my 1903 house that had the foundation replaced.

The wall constructions is studs, turned either short or long side out, and then board and baton style sheathing, and then lap siding. The board and baton form a sort of drainage plane behind the siding. However, there's no building paper vapor or air barrier over the sheathing, and the boards seem like there are plenty of air leaks between them. The walls have cellulose insulation, and the siding is covered with asbestos cement shingles, which I hope to remove some day.

The dilemma is this:

In Energy efficiency and durability | Asked By Adam Liberman | Jan 11 12
5 Answers

Can anyone help with info (esp. technical documentation) about whether vented (soffit-ridge) or unvented roof assemblies are more resistant to high wind load damage?

A customer of mine is being told by his builder that he can't switch to roof deck spray foam and an unvented attic because that will change (reduce) the resistance to wind loads compared to the as-designed house with soffit and ridge vents. We are in a 130 mph wind zone.

In Energy efficiency and durability | Asked By Kevin Veach | Jan 10 12
5 Answers

Venting REMOTE insulated walls

I've been looking for a video article I saw in the last (2) months that covered the subject of providing a vent path at both the top and bottom of a wall insulated with rigid insulation at the exterior. The general concept was to place a thin strip of fiber-mesh type material between the 1x4 strapping bays at both the top and bottom. I remember the top end detail but the lower end detail is what I can't remeber accurately.

In GBA Pro help | Asked By Harry Seidel | Jan 11 12
15 Answers


I was nosing around on wikipedia and I came across the statement below regarding radiant barriers in wall assemblies.

I'm skeptical...
Can anybody verify that "wrapping a house with radiant barrier" can produce such results?

In Energy efficiency and durability | Asked By Lucas Durand - 7A | Jan 10 12
1 Answer

Icynene Spray Foam on Underneath Side of Roof Deck - Zone 5

After reading for months, getting 4 quotes from spray foam contractors in my area, and undergoing an energy audit, I'm in the process of finalizing plans for open cell half-pound Icynene application to the bottom side of the roof deck in the attic. This is a retrofit job. Within the attic is a furnace in a closed room vented directly to the outside. I have a few questions after I received the proposal today from the contractor

In Energy efficiency and durability | Asked By Kevin Hilton | Jan 11 12
Register for a free account and join the conversation

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