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3 Answers

New Green Basics page

When we built GBAGreenBuildingAdvisor.com a few years ago, we wanted to produce an information resource for everybody. Something that would help you get from where you are to where you want to be in Green building, remodeling, and design.

We wanted to help all – builders and remodelers, architects and designers, code officials, consumers, product manufacturers – anyone who wanted to take their game to the next level.

In General questions | Asked By Daniel Morrison | Mar 14 12
9 Answers

BPI certification

I cannot find much information on the BPI website with regards to BUILDING ANALYST certification and ENVELOPE PROFESSIONALcertification. Would I need both to get a job in the energy auditing field? Is one better than the other? I already have an extensive background in construction.

In GBA Pro help | Asked By william goodwin | Mar 13 12
2 Answers

How can I insulate an open crawl space under an existing finished room?

I want to insulate under an existing finished room. The room's foundation is pressure treated post and beams. The previous use of the room was a screened porch/deck. I was planning to frame the exterior walls and insulate. I was planning to install OSB sheathing, House wrap, Rigid foam, wood furring strips an finish with vinyl siding. There is an existing basement window that could be opened to this space. The space in the floor joist has fiberglass batts, kraft paper up toward the finished room and Homosote on the underside of the joist (exterior underside finish). Is ventilation a concern?

In Energy efficiency and durability | Asked By Mike McGann | Mar 15 12
3 Answers

How big should my custom home be?

I will be building a custom home. It will be around 6,500 sq ft. I would like to know how big of a house can be built and still be energy efficient?

In General questions | Asked By leon boutte | Mar 15 12
1 Answer



We have been doing some back-end development work on GBA and had a 'permissions' issue creep in. A lot of people experienced problems, but the problems were not visible to Martin and I because we are administrators will full permissions.

Things should be back to normal now, and if it happens again, we now know how to solve the problem. We have some developers working right now on tracking down the source of the problem, so please have patience with us if things continue to be a little sub-optimal over the next day or so.

In General questions | Asked By Daniel Morrison | Mar 8 12
1 Answer

Heated line in attic crawl space

My house has some unfinished crawl spaces where the heater pipe line runs trough. In the winter i get ice dams due to the loss of heat. Should I spray insulation over the expose copper lines to keep this spaces cold or should i spray the roof rafters? I tried insulated sleeves but don't seen to work.

Thank you for your responses.

In Energy efficiency and durability | Asked By nestor lopez | Mar 15 12
3 Answers

Flash and batt and Vapor barrier / retarder

Hello GBA,

I have a builder who is building in Zone 5 / 6 line (NH), 2 x 6 w/ a "flash and batt" wall insulation strategy. I haven't been a fan of the F&B strategy in the past, and not sure I will become one w/ this job either.

2" CC, R6.5?? sprayed 1st, w/ an R15 high density f'glass batt going in 2nd. The builders question is: What, if any, vapor barrier or retarder s/b used?

In Energy efficiency and durability | Asked By Kevin Hanlon | Mar 14 12
5 Answers

Ventilating Stairways in Multifamily Buildings on the Cape

I am renovating a five building development in Orleans, MA that includes a new envelope (windows, added insulation on the exterior and new siding). I am also planning to add fresh air to the small (2 stories) stairwells in each building. Should I be concerned about humidity so much that I add a cooling system as part of the ventilation? There will be continuously running bath fans in each unit and existing through wall AC units. I don't want to overdesign for a few days a year that I might generate condensation because I am not cooling the make-up air.

Thanks for any help.

In Mechanicals | Asked By julie klump | Mar 14 12
34 Answers

Retaining heat at a garage door; part 2.a.07x

Fairbanks, AK, zone 8. This is an iteration of a design I asked about last year; different foundation system, somewhat different ramp. I looked for that thread to see exactly what was said, but could not find it, so I apologize if old ground is being dug up again.

I am still struggling with getting some kind of heat retention at a garage door, a desire that may be nearly pointless given that garage doors notoriously leak. (That said, I was sitting inside my neighbor's the other day at 20 below, and could not detect any leakage by hand, fwiw. 2 story, non-super-tight house.)

In General questions | Asked By John Klingel | Jan 24 12
1 Answer

Exterior Foam Thickness - Atlantic Canada


It seems that the concept of an interior moisture venting is quite new and some experienced builders brush off the idea.

I am looking at building a house I will personally live in, and I intend to live in comfort, on reasonable energy efficiency, and of course durability of structure.

The design I am currently looking at would consist of; from outside to inside:

-Properly screened air gap
- 2 x Layers of 2" Polyiso with joints sealed and staggered
- Tyvec Drainwrap (adhesive membrane flashing)
- 1/2" Plywood
-5.5" wet blown cellulose in 2 x 6 framing 24" c/c

In Energy efficiency and durability | Asked By Jean-Philippe Levesque | Mar 14 12
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