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!


The designers at my firm have enjoyed using Tectum roof deck systems:


We are trying to avoid using XPS because of blowing agent issues, so we were encouraged to find out that Tectum offers an EPS option. Ideally though, they would offer a polyiso option. Since they don't, do any of you know of a similar product out there that offers polyiso instead of EPS or XPS?


In Green products and materials | Asked By Heather Gayle Holdridge | Nov 17 11
1 Answer

I have an air handler in my attic space. The attic is out of the envelope and I would like to build a rigid foamboard box around it to maintain a more even temperature. Should I vapor barrier (Fypar) the inside of the box, the outside, or neither?

It blows heat in the winter and AC in the summer. Of course, its surroundings are just the opposite. Any input would be appreciated.

In General questions | Asked By shane claflin | Nov 17 11
4 Answers

Also, what details are necessary to permanently - place a generator near a home. For example a grounding rod..

In Energy efficiency and durability | Asked By FRancis Gamza | Nov 16 11
12 Answers

I am the un-proud owner of a new home constructed 1 year ago. I have terrible problems with air leakage particularly from the attic where blown cellulose is used. Due to this problem and after reading your columns, I called a BPI certified Energy Audit Company to perform a blower door test.

Prior to testing the company came and turned off all the furnaces and hotwater heater. The gas dryer and stove were not running.

In Energy efficiency and durability | Asked By Kevin Hilton | Nov 16 11
3 Answers

I am building a small 750 square foot cottage and have achieved 1.24 ACH at 50 pascals before applying the drywall/plaster finish. Is there a standard target ACH before the walls are finished? The walls are insulated with foam and I am trying to figure out whether we can achieve .6 ACH by finishing the walls or need to do further air sealing.

In PassivHaus | Asked By Steve Snyder | Nov 16 11
3 Answers

We live in Massachusetts and recently replaced our roof with Ecostar plastic shingles and the rep forced the roofer to expand our soffit vents and ridge vents as part of the installation. We had a much delayed energy audit in the midst of the installation and the recommendations have put us in the middle of what seems to be an experts' dispute. The energy consultant says seal the soffits, spray foam and dense pack the closed rafter area leading from the second floor knee wall to the attic flat.

In Green building techniques | Asked By Stuart Warner | Nov 16 11
6 Answers

I've been chasing a low-cost flow hood for monitoring performance of my ventilation system for some time now, hoping to get one used, or through my HERS rater, and recently discovered a comment made by Martin here on June 15th '09 referring to a way of making a homemade flow hood "from a cardboard box and a $90 digital anemometer". (Right under my nose)

Can you give us an updated design for such an elegant contraption and recommendations for what anemometer to buy and what other diagnostic tests we might be able to accomplish with it? the choices on these things is overwhelming.

In Mechanicals | Asked By Michael Chandler | Nov 15 11
49 Answers

I thought I recently read an article on the Building Science website talking about problems installing batt insulation over spray foam - moving the dewpoint to the spray foam layer and causing the batt to get moist where it meets the foam. Now I can't find it anywhere and am wondering if I understood it correctly.
Can anyone explain this to me better or point me to more information. Thank you so much.

In GBA Pro help | Asked By Amanda Evans | Jun 23 09
5 Answers

My home is a 1985 passive solar timber frame with wrap and strap construction located in southeastern MA. The roof deck is 1x6 TandG followed by a plastic sheet ->3in polyiso ->1in polyiso ->plywood-> shingles(no paper). The shingles are ready for replacement and there is known rot at the sheathing around the vent stack which was never sealed(spray Foamed). In replacing some siding (2in polyiso w/vented rain space and clapboard) I noticed that there is no tape or other air sealing.

In Green building techniques | Asked By T White | Nov 10 11
5 Answers

My main roof is hipped, with cornice all sides. Can i use the iso board with paper face to insulate the rafter bays from inside?

I would lay it against the sheeting, leaving 1'' of air space, and seal with 2" of foil faced foam board sealed with foil tape. Strap with 1x and finish with 5/8 drywall, creating habitable space. Roof has new light colored dimensional shingle.

In Energy efficiency and durability | Asked By richard miller | Nov 15 11
Register for a free account and join the conversation

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