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1 Answer

Can 1.5" and 2.0" unfaced XPS be used as a continuous rafter baffle?

I am considering using either 2.0 or 1.5 XPS as a continuous rafter baffle (from soffit to ridge vent) using a 2" vent between the XPS and the the roof deck. The rafters are nominal 2x10s and the underside of the rafter will be insulated with Roxul and then covered with finished plywood with a high quality latex paint (Class II or preferably Class III vapour retarder). I have only seen 1" XPS recommended by GBA. Can a thicker board be used or is there concern re: drying to the exterior given the relative impermeance of the thicker board?

Asked By Andreas Seibert | Oct 18 16
1 Answer

ERV ducting options for existing construction?

I have taken Martins advice from a past discussion and added an ERV to our home. Currently the ERV is setup in the easiest install method by adding the fresh air and exhaust air ducting from the ERV to our return air for our furnace. Our furnace blower has an ecm blower so we are not taking a huge power hit as it pulls about 100 watts. The drawback to this is that we have two independent HVAC units serving the home, each on opposite ends of the two story house.

Asked By Jeremy K | Oct 17 16
7 Answers

Is our builder responsible for the wrong height of the ceiling?

We walked through a model home, liked the floor plan and choose to build that plan. Our home and one other home (with the same floor plan) were being built at the same time by same framers.

The ceiling in the hallway was a certain height to accommodate crown molding. The project manager came to us and said the crown molding couldn't go all the way around because of the height of the arches, so we could have it come around and stop on each side of the arch or lower the arches.

Asked By Courtney Spitz | Oct 11 16
2 Answers

Vapor barrier?

I have read your articles on vapor barriers and retarders and have a question about my cottage.
The basement is block wall construction (9' high) and is below grade for most of it (on 3 sides - walkout on one side which is wood frame construction on that side).
The floor is poured concrete.
We are in the 5A or 6A area of Ontario Canada.
The cottage is not air conditioned in the summer.
The block walls are spray foamed with 3" of closed cell foam.

Asked By D B | Oct 10 16
3 Answers

Questions about humidity control in unconditioned space

Two locations: Zone 3A, coastal N.C. (fishing cabins converted to a non-profit retreat facility—insulated and heated, but no AC); and Deccan Plateau in central India —wet, continuously humid 3-month monsoon and scorching hot & dry 4-month summer (HVAC nonexistent).

Primary question: how can mold and mildew issues be prevented and/or managed in an unconditioned space?

Asked By David McNeely | Oct 5 16
1 Answer

Crawl space insulation climate zone 6B, 7000 feet elevation, low humidity.

I have a question regarding an existing home in climate zone 6B located about 7000 feet in elevation?

Asked By Gary Macdonald | Oct 6 16
1 Answer

Rebuilding old passive hot air solar panels

I am trying to rebuild a passive hot air solar panel manufactured by Great Western Solar company (no longer in business under that name). The box is aluminium with lascalite fiberglass for the transparent cover. Because the cover, angle aluminum and fibeerglass sheet seems to be glued down and then riveted, for the life of me I can not get it off. So, my idea was to cut out the lascalite sheeting and install a new type of plastic cover and overlay new angle aluminium over the top of the old.

Asked By Tom Gordy | Oct 5 16
3 Answers

When installing an HRV, can I replace the existing air makeup duct with a tandem duct and plumb my fresh air into the makeup?

It looks to me like the air makeup duct on my furnace could be replaced with the new air in from my HRV. Will this constant flow from the HRV upset the pressure balance in the furnace?

Asked By Steve Nelson | Oct 2 16
7 Answers

Ceiling vapor barrier for indoor pool room


We are in the process of designing an indoor pool building based off of the general concepts in Dr. Joe Lstiburek's article "In the Deep End" (, however, mine is a residential building with wood frame construction and an asphalt shingle roof with wood trusses. I'm in Zone 4 (Maryland).

Asked By Dan Theman | Oct 1 16
2 Answers

Can I install 3/8" T-1-11 clear siding over existing 5/8" T-1-11 siding to create a board and batten look?

My house is currently sheathed in 5/8" T-1-11 siding. I'd like to add another layer of 3/8" clear (no grooves) T-1-11 siding over that and then add 2" battens to create a board and batten siding look. Is this a good idea or a recipe for disaster? I live in Maui on the dry side of the island and get a lot of sun on the south and west sides of my house.

Thanks and Aloha,

Asked By Bruce Lowrey | Sep 29 16
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