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!

11 Answers

Ventless propane heaters in crawl space

I just looked at a residential repair job (replacing leaking skylights) and the homeowner showed me some work that was recently completed in their crawlspace. A contractor had installed two ventless propane heaters in an uninsulated crawl space to supposedly save energy!

It is a second home with electric resistance heat at over 5,000 feet in the North Carolina mountains. The crawl space has an incomplete vapor barrier, sealed vents and obvious moisture problems with mold and non PT sill plates starting to rot.

In Energy efficiency and durability | Asked By Travis Thompson | Sep 25 10
8 Answers

Suggestions for insulation on ceiling of wet crawlspace?

For a super insulated house being extensively retrofitted in South Jersey(r40 walls, r70 attic, triple pane windows) with a permanently wet crawlspace (riverfront, high water table), I am considering insulating the ceiling of the crawlspace.

In Energy efficiency and durability | Asked By Michael Arnold | Jan 19 13
1 Answer

Air-tight Construction Caused Plasterboard to Blow Out?

We had cellulose blown into a remodeled wall this week-end. Plasterboard broke open under the pressure. The installer blamed the air-tight construction. Does this seem right?

We re-built a wall in our home. The exterior plywood sheathing was caulked against the studs and the seams sealed with Siga Wigluv tape. The interior studs were caulked then Siga Majpell stapled and sealed with Siga Sicrall tape and Conservation Technology gaskets applied to boundaries where plasterboard was applied. The plasterboard was screwed in place per code and then caulked and mudded.

In Green building techniques | Asked By Deb Davis | Jan 22 13
6 Answers

Should balloon-framed houses with open crawlspaces be sealed?

Given a "historical" (ca. 1910) wall assembly, plaster/lath -> framing -> siding (no insulation, sheathing, or vapor barrier), does it still make sense to seal the crawlspace? Is it risky, much like adding insulation w/o also rebuilding the exterior wall to add a rain screen can be?

In Green building techniques | Asked By Matt Goff (zone 2A) | Jan 14 13
3 Answers

How best to insulate newly built garage with flat roof


I live in Chicago (city of), Zone 5, and I have a new detached 2 car garage 20x20x11. The construction is wood frame with metal siding, drywall finished on the inside. I'd like to heat this garage to 50F during the winters in a cost effective manner (both insulation cost and energy cost), but I also want to do this right and not cut corners. I plan to heat this garage with a small ceiling mounted gas heater, like a Reznor unit.

In Energy efficiency and durability | Asked By Brian CL | Jan 22 13
5 Answers

Blowing dense-packed cellulose into Larsen truss walls and open rafter bays

This is what is keeping me up at nights:

Larsen trusses have no stud cavity walls and in my building the trusses are also open to the rafter bays (i.e no top plates).

I assume it’s the resistance to the blow by the walls and plates of the cavity which enable the density. I will be blowing cellulose into spaces with no boundaries so how to do I get the density and how do I know I have reached it?

Is it all about feel (i.e. resistence to the hose) and sound (i.e. back pressure while blowing)?

In General questions | Asked By Oak Orchard | Jan 21 13
3 Answers

Triple-glazed fiberglass windows - Zone 5A

What options exist presently for affordable triple-glazed fiberglass windows in New England? I like the wood interior of Integrity, but wonder if anybody has found windows that hit a sweet spot of performance, price, reliable customer service. Until recently, I'd been considering Intus windows, but ultimately don't want PVC or unpaintable, white interior sash and frames. Thanks!

In Green products and materials | Asked By John Rockwell | Jan 18 13
1 Answer

Bathroom ventilation

This is a followup on a question by Jim Blodgett on 7/5/2009 titled Bathroom/Laundry Ventilation through HRV. If I understood the responses to that question, a HRV can exhaust a full bath without separate ventilation through the roof or wall. There was some reference to boosting the exhaust into the HRV with a fan while showering. This in addition to the boost to maximum of the entire HRV by a wall control.

In Mechanicals | Asked By tom ruben | Jan 21 13
7 Answers

Why are bath fan dampers so lousy??

I just installed a couple of Panasonic WhisperGreen bath fans on a job, and before nailing them in I took a close look at the internal backdraft damper. I had two different types on the job... one had a curved plastic damper like a potato chip, the other had a flat piece of thin aluminum, which I am used to seeing. Both types had a gap all the way around the perimeter... not a large gap, but there was no foam seal there, and I'm sure these will let in a lot of outside air during the blower door test, as well as during some windy conditions.

In Green products and materials | Asked By David Meiland | Jun 17 11
8 Answers

Vapor Barrier to Prevent off gassing of CCA treated wood and OSB ?

I am in the middle of house building for a passive solar designed house in a mild marine Climate in southern Chile ( similar to Portland Oregon) where likely using a vapor barrier would not cause problems from what I understand.

The house frame upper and lower floor was built with OSB which I understand contains formaldehyde and CCA pressure treated wood. These are common construction methods where I live.

In this case might someone recommend a vapor barrier to prevent off-gassing from the CCA wood and formaldehyde in the OSB ?

In General questions | Asked By marion marshall | Jan 19 13
Register for a free account and join the conversation

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