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!

10 Answers

We own a circa 1920s renovated farmhouse in eastern Nebraska. Over the years we have been making improvements to the home's performance. This summer we finally knocked a hole in the second-story ceiling to get a look at the attic space for the first time. The second story was always bitterly cold in winter and extremely hot in summer.

In Green products and materials | Asked By Kristina Thompson | Oct 2 10
4 Answers

I represent a PU injected SIP company (Eco-Panels) that uses an imbedded cam-lock system and has patented structural fully insulated corners. With our system, we significantly reduce thermal bridging, but still face the challenges of using standard framing materials for pre-framed window and door rough openings and bottom and top plates. Can any of the professionals on this site provide me with some alternative structural materials that increase overall thermal performance whether it be reducing thermal bridging or increasing R-value?

Craig T. Payne

In Energy efficiency and durability | Asked By Craig Payne | Jun 7 11
6 Answers

We are just about to begin construction on our new home. Our exterior wall is designed to be (from the outside to inside) clapboard siding, strapping, felt paper, 2" polyiso, plywood, 2x6 wall with denspak cellulose, drywall. It is going to be slab on grade construction with frost walls. We are insulating under our slab with 4" of insulation and including a 2" thermal break between the slab and frost wall at the slab shelf.

We are waffling between the following:
1.) Using 2" of XPS on the outside of the stem wall
2.) Using 2" of XPS on the inside of the stem wall

In Energy efficiency and durability | Asked By heidi davis | Jul 25 11
3 Answers

I am located in 4a climate zone. What is the preffered way to insulate a pony wall in a conditioned/closed crawl? We are using thermax on the masonry section, batts in the rim, but would like to know what the best way to do the pony wall would be? I saw where one builder used radiant barrier??

In Energy efficiency and durability | Asked By Todd Zarzecki | Jul 26 11
3 Answers

Based on the Martin’s article and related research in the links he provided, unventing my crawl space in the hot-humid southeast (Climate Zone 3A) seems like a good idea.

In Energy efficiency and durability | Asked By Steve Robertson | Jul 25 11
3 Answers

I am planning on installing 2 minisplit heat-pump units to heat and cool a home we are building. It is a new home just south of Boston, MA, about 2,800 sq. ft., tightly constructed, R-35 walls, R-55 ceiling.

The Manual J and D calculations have been done, indicating I would need approximately 33,000 BTU to heat and under a 2-ton system to cool. I am planning on meeting with a minisplit heat-pump rep to discuss the best options for the home.

In Mechanicals | Asked By james magner | Jul 25 11
10 Answers

Three years ago we remodeled a basement in a 1920's vintage house. The foundation is poured concrete. In all but two little 8'x8' areas we sprayed 2-1/2" of a closed cell urethane foam over Platon drainage matt which was installed directly to the concrete wall. The Platon was channelled into a subslab drain tile that we cut into the floor. We then installed 2x4 walls, uninsulated and drywalled.

In Energy efficiency and durability | Asked By Sam Breidenbach | Jul 14 11
1 Answer

What do you think is the best way to go about buidling a double stud wall?

Is it better to use spray foam insulation a couple inches thick, followed up by cellulose and let the exterior sheathing dry out?

My idea for a cost effective way to do this is double 2X4 wall approximately 10 inches apart. 2 inches of closed cell foam on the inside to stop water / vapor. Fill the rest of the cavity with cellulose then drywall it. Outside sheathing will just be normal tyvek housewrap with vinyl siding.

In Green building techniques | Asked By Denis Recchia | Jul 26 11
6 Answers

I was trying to finalize my ducting options with a Fantech ERV. I am installing exhaust vents in each bathroom. Now the fresh air --

The manual states:

"Furnace blower may be required to operate when ERV is on to provide good air distribution"

May be? May be not?

If I chose to duct the supply air stream to the cold air return, I don't want to have the HVAC unit run continously. How do I make this determination?


In Mechanicals | Asked By John Nooncaster | Jul 25 11
0 Answers

We are almost done building our front porch using FSC ipe and now need to decide on the sealer. Would like to add a stain with the sealer as well.

So far we are looking at Vermont Natural Coatings PolyWhey Exterior Clear Wood Finish, Seal-Once Exotic Wood Waterproofer, and Weather-Bos.

Any comments on these brands or are there other brands you prefer?
Thank you!

In Green products and materials | Asked By Karen Miller | Jul 26 11
Register for a free account and join the conversation

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