Q&A: A Forum for Green Building Experts and Beginners

[Click map to enlarge]

drawing of climate zone map.gif

Advice can depend on climate -- Please specify in your question.

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!

Ask a Question >
1 Answer
HRV / ERV for a conditioned crawlspace

I'm in climate zone 5-6. 3' conditioned crawlspace, with 12mil. plastic sealed floor & closed cell spray foam insulation installed on crawlspace walls & rim joists. Forced air gas furnace- ducts into crawlspace with one small flapper vent allowing some air into crawlspace when furnace/ ac is running. I currently run a dehumidifier about 12-24 hours a week in summer months to maintain a humidity level consistent with main floor. I'm about to seal the main level with new windows and 3" of polyso around exterior, and thus also want to install an HRV/ERV.

In General questions | Asked By stu m | Mar 2 14
9 Answers
I need suggestions for a high-performance dryer vent

Building a LEED Platinum house and need info on drier vents and rangehoods with make-up air

In GBA Pro help | Asked By david dickson | Feb 11 14
2 Answers
Waterless vs. ultra efficient urinals

I am planning on installing one in my house & want to know if anyone has an opinion or experience w/ which would require less maintenance over time.

In Green products and materials | Asked By Eddy Hogan | Jan 24 14
1 Answer
Damper control motor

I have a 36" whole house exhaust fan mounted in an attic dormer with a gravity damper. I want to add a damper control motor. Problem- the fan is a two speed, wired from down stairs and the damper motor needs only one input. I think I need a relay to make it work. What kind of relay is required? Thanks.

In Mechanicals | Asked By Jim Phillips | Mar 1 14
2 Answers
Prepping the rim joist for spray foam in cold weather

I live in upstate NY (climate zone 5 or 6; I'm right on the line) in a brick house that was built in 1850. My foundation walls are at least 14-in. thick stone (with mortar joints). I believe the house is balloon framed, but I haven't lived in it long enough to figure that out yet. I've heard from the previous owners that there's blown cellulose between the walls and the brick. There's some evidence on the exterior that this might be true.

In Energy efficiency and durability | Asked By Chris Ermides | Feb 13 14
3 Answers
What is the best flash-and-batt approach for a low-pitch unvented cathedral assembly?

New 2600 sf house is a low-pitch 1 1/2 : 12 shed standing seam metal over plywood sheathing on 1 3/4x14 LVL's 24" o.c., drywall ceiling. Zone 3 SF bay area; site is a north facing downslope just into the hot-dry 3B Zone, but sharing much of the climate of San Francisco's 3C. I have in mind 2" closed cell foam, either rigid panels sealed in place to joists with spray foam, then filling remaining cavity with 12" net thickness R38 batts; or 2" nominal spray foam, with 12" of R-51.6 blown in spider fiberglass secured by netting.

In Energy efficiency and durability | Asked By brian rawlinson | Feb 27 14
5 Answers
Insulating scissors trusses — best practice or economics?

I'm going to build a one story house with walk out basement in northern Idaho, east of Coeur d'Alene. The main roof will be scissor trusses with a 16" heel. With an 8/12 pitch roof and 4/12 pitch ceiling. Due to the spans, there will probably be a 7' to 8' space at the peak between the roof and ceiling. The roof will be standing seam metal and the finish ceiling will first get a taped drywall ceiling and thane 1x T&G boards over that.

In Green building techniques | Asked By James Mills | Feb 28 14
1 Answer
Depressurization

Well, I recently built a new home, (its of sip construction) and it would appear that my attempts to ensure it airtightness have been quite successful. I haven't actually tested or measured its airtightness so my opinions are solely based upon observation. I didn't install a HRV although technically the code called for it because my experience with operating HRV's has been mostly negative.

In General questions | Asked By Glenn Thornborrow | Feb 28 14
5 Answers
Recommendations for finishing a house on island in SE Alaska?

I purchased a partially completed house on a small island 80 miles south of Juneau. The 40x30, 2.5 story house is built on pilings with 2x12 floor joist on 16" centers, 1x6 walls, 16" oc, a combination of 5/16th osb and plywood, wall sheeting, all windows and doors installed, a finished raised seam metal roof, second floor (2x12, 16"oc and stairway done, and minimal inside framing accomplished. The amount of framing in the house shell is really overdone!

In GBA Pro help | Asked By Michael Parnell | Feb 28 14
4 Answers
Strange venting and ice dams

I visited an acquaintance's house last night for another "informal
energy audit", as he was complaining of ice dams bad enough to
bring a little bit of water drip into the top of a couple of window
frames. Boston area, zone 5, and our thermal rollercoaster of
the winter we've been having. The house is typical early-nineties
vintage split-level, simple 6-in-12 or thereabouts roofline with
maybe 5 - 6 inches of blown-in fiberglass on the attic ceiling.
Ridge vent most of the way along. The rafter bays have those token
styrofoam vent channel pieces sitting at the eaves but not nearly

In General questions | Asked By Hobbit _ | Feb 28 14
Register for a free account and join the conversation


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