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!

6 Answers

We are planning to upgrade the insulation in only the renovated areas of the house, with either foam or dense-packed cellulose. Will the increased air-tightness in those areas force warm/moist interior air to seek equilibrium by moving through exterior walls that have not been upgraded, dramatically increasing the amount of air moving through the poorly-insulated walls and causing cavity condensation?

In Energy efficiency and durability | Asked By todd Stanley | Oct 21 11
3 Answers


Can someone educate me on typical heating costs for a semi-detached vs completely detached home? I'm considering two homes and both are about 2000 sq feet. I've heard the average in this area in NYC during cold months is about $500/month for detached homes but can't get a number for the semi-detached. The broker told me it will be 1/2 or 1/3rd of a completely detached home but that seems hard to believe

Does anybody know if having a shared wall saves you that much in electricity costs?


In Energy efficiency and durability | Asked By sam dhak | Oct 25 11
1 Answer

Can HPDE piping be used for domestic water plumbing as a substitute for PEX? I'm concerned about the health issues around PEX? Any drawbacks to using HPDE in potable water plumbing applications?

In GBA Pro help | Asked By Peter Schonherr | Oct 26 11
2 Answers

Hello all,
I've always read that basement wall insulation should be semi permeable to water vapor, allowing the wall assembly to dry to the interior,... but I don't recall ever reading why.
If one was to apply a foil faced foam board, or a closed cell spray foam directly against the concrete wall, what's the danger?


In Energy efficiency and durability | Asked By Richard Baumgarten | Oct 26 11
1 Answer

In a visit to Vancouver to speak with the mayor Gregor Robertson and environmentalist David Suzuki, Thich Nhat Hanh joins a conversation concerning the state of the environment and how to enact positive change.
For those unfamiliar with the teachings of Thich Nhat Hanh during the video he may seem to be not addressing the questions posed to him directly, but if you watch the entire video you will see that in fact he has, repeating his most important messages.

In General questions | Asked By j chesnut | Oct 25 11
8 Answers

We're building a very tight house, and are trying to figure out what floor finishes to use.

Our floor contractor (who we very much like and respect) is recommending an analine die (with 0 VOCs), 2 coats of Bona Woodline Satin (510 g/l VOC!), and a top coat of Bona Traffic (180 g/l VOC). A few questions:

*He says that after 2 weeks of curing, that there will absolutely zero VOC offgassing with these products - will that be the case?

*Is there any reason not to use the Woodline 350 product instead of the Woodline?

In Green products and materials | Asked By Karen Miller | Sep 26 11
9 Answers

Hi all. I have been reading some of the roof venting strategies and have not yet figured out my answer. We are in the middle of building our new home which was constructed with trusses for a multiple hip (courtyard in a ranch style house) roof.

In Energy efficiency and durability | Asked By Mark Dickerson | Oct 23 11
10 Answers

Cabin in Blue Ridge Mountains of VA originally built as tractor shed 35 years ago.

In Energy efficiency and durability | Asked By Pedro Mule | Oct 21 11
3 Answers

I cannot afford the insulated vinyl siding, so I am looking at some type of fan-fold foam insulation - or flat insulation, then a Tyvek material, then the vinyl.

And does the thickness of the vinyl -- .040 - .046 -- really make any difference in strength and for insulation?

Thank you for any information you can enlighten me with.

Sincerely, jan

In Energy efficiency and durability | Asked By jan wisocki | Oct 24 11
1 Answer

I am building a new house and plan to use Green Fiber cellulose for wall (dense packed) and attic floor (loose) insulation. I was told that cellulose does not work for subfloor insulation. We have raised foundation with 2' vented crawl space in California.

I don't mind using fiberglass in closed cavity walls and plan to use it for interior walls for sound barrier. However, I prefer not to use fiberglass for subfloor insulation. Is there any other alternative?

In Green products and materials | Asked By Rian Bart | Oct 24 11
Register for a free account and join the conversation

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