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!

2 Answers

Any value to ceiling insulation when constructing a conditioned attic?

I'm ready for insulation in my retrofit project, zone 3 in North Carolina. The building has 1 1/2" of poly foam on the exterior 2x6 walls, which will be filled with cellulose. The roof deck has 3" of poly, the underside will have 6" of open cell foam sprayed onto the underside of the roof deck. My question: The insulation contractor has suggested that I may want to add 6" of cellulose blown in at the ceiling level. I can see some value here preventing sound from migrating between rooms (common walls will be insulated for sound as well), but is there any thermal benefit to be gained here?

In General questions | Asked By Bill Savoie | Jan 25 13
1 Answer

I have heard a lot of talk about our homes of today not outlasting our 30 year mortgage. I would love to hear more about this topic.

Code built house will not last as long as mortgage.

In Energy efficiency and durability | Asked By terry herndon | Jan 25 13
4 Answers

International Residential Code

Is the International Residential Code available online, free, anywhere? If not, is there anything equivalent available -- at least good-enough for a DIY builder?

Looking at Abebooks I see that I can get 2000 and maybe 2003 or 2006 versions for less than $15.


How much different are these older versions compared to the latest version? How helpful is it to a DIY builder to have access to the International Energy Conservation Code?

In General questions | Asked By Jack Woolfe | Jan 24 13
1 Answer

Flash and Batt foam thickness

I'm in NJ climate zone 5 and have a project with an installed falsh and batt with 1" closed cell foam and Roxul batt in wood framing. I usually spec 2"+ but would like to avoid ripping everything apart and spraying more foam. Is there a chart/rule-of-thumb anywhere showing wtih of foam based on climate zone averages or any specific data to justify thickness besides doing a calc? This seems like a case where it would probably be ok but with a small chance for a big problem??

In Energy efficiency and durability | Asked By Michael Margulies | Jan 25 13
0 Answers

Seeking framer familiar with exterior rigid insulation in Southeast MI

My wife and I are building a new home in Royal Oak, MI with anticipated May start. Our general contractor is having difficulty finding a framer familiar with the installation of exterior rigid foam. Any referrals would be greatly appreciated.

Our planned wall assembly:
2x6 framing
2-3" of polyiso (2 layers with seams staggered)
WRB - tyvek or similar
Furring strips

In General questions | Asked By Troy Stevenson | Jan 24 13
0 Answers

Commercial windows in residential application


I have a residential house project starting this spring in Breckenridge, Colorado (8900 elevation). Our house has a contemporary design and would like to put commercial windows in the majority of the house. Local building codes have adopted the 2006 energy code and require .35 U value for the fenestration opening. I have several questions regarding this issue.

In Energy efficiency and durability | Asked By Bret Bonenberger | Jan 24 13
15 Answers

Another retrofit tale

If I have to phrase a post as a question, I guess this one boils
down to "so, whaddaya think?"

I managed a DER on my own house over the summer, and some of you
possibly saw some of my questions that stemmed from that. At the
risk of tooting my own horn a little, I'd like to start giving back
to the community by sharing the MONSTER writeup I've done about the
project -- and there's more to come, as I collect and compare energy
stats over the rest of this winter. At almost 120,000 words it's
easily book-length, but right now it's just a set of simple web-pages

In Green building techniques | Asked By Hobbit _ | Jan 11 13
2 Answers

Applying housewrap

I didn't read all of your questions/answers but after reading quite a few, I didn't see where there was a mention of a right and wrong side to housewrap. I would think to ensure that a product would perform to it's highest standard, ensuring there would be proper escape of moisture through the product,this innovation would have a right and wrong side; correct, or does it matter? In other words, apply the housewrap to walls with the print facing out.


In Energy efficiency and durability | Asked By Charline Bridgeman | Jan 24 13
1 Answer

A few unvented crawl space questions

I am detailing an unvented 600 sq. ft. crawlspace that is 4' high. The exterior side of the concrete wall is insulated with 5" of EPS and has been damp-proofed.

My plan now is to insulate the floor with 3" EPS and cover with two layers of poly that will be mechanically fastened with horizontal battens and acoustic sealant to the side of the footing. to boost the R-value in the wall i will add 1.5" XPS and then build a stud wall to cover with gypsum wallboard.

In General questions | Asked By erik olofsson | Jan 24 13
0 Answers

Cold air infiltration through a power-vented water heater

I was wondering if anyone has a solution for this problem.

I recently installed a power-vented natural gas water heater to replace a 20-year-old electric.

The installation was done by me and inspected by both a gas fitter and the local gas company. All is good...

However, there is a significant amount of cold outside air coming in the 2" (system 636) exhaust from the power vent, and its enough to spin the fan on the power vent backwards. (when not running of course)

In GBA Pro help | Asked By R Hunt | Jan 24 13
Register for a free account and join the conversation

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