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1 Answer

Could plastic attic ventilation baffles on a 5/12 roof create a moisture problem?

The article on attic ventilation baffles notes two pretty good commercial products, Accuvent and Smart Baffle. Both are made of plastic, with essentially zero vapor permeability. With a steep pitch roof, that's fine. Any vapor that come up through the ceiling, through a leak or through vapor diffusion through the drywall, can keep going up through the insulation and reach the vent space above the insulation, so there's no moisture trap.

Asked By Charlie Sullivan | May 31 16
52 Answers

Do heat pumps and super insulation complement or compete with each other?

After reading the article on "how much insulation is too much", I found Marc Rosenbaum's stats on 11 cold climate house configurations interesting. He points out that the difference in energy savings is very small between a minimally insulated and poorly air sealed house and a super insulated and very tight air sealed house. This is because he starts with an 2.5 cop heat pump and a heat pump domestic water heater. He sets the miscellaneous loads (appliances and lighting) at 4800 kwh year. The domestic hot water at 1850 kwh year, and the only variable is space heat.

Asked By ven sonata | May 29 16
0 Answers

Has anyone studied or quantified how xps foam shrinks?

I am working on the foundation for a new house I am building for my family. Under the pad I am putting a 3.5" layer of reclaimed XPS. Then I got thinking that I should put something over top of that to overlap any seams. So the lumber yard had 4X8 sheets of .5" of XPS which isn't a lot of R-value but I mostly wanted something over the seams in the thicker reclaimed XPS. I know EPS is better for the environment, but they didn't have any. Anyway I took my time and really made sure the joints were tight and everything laid in nice without any gaps.

Asked By Dillon Vautrin | May 31 16
7 Answers

ROI and incremental costs

The topic of ROI seems to permeate a lot of the discussions of both building envelopes and heating components. I wonder if the way we look at it really takes into account the realities of the way the North American building industry works?

Unlike most of the projects here on GBA which are either custom or owner-built, the overwhelming majority of house construction is speculative - that is financed and built by developers with no input from the eventual owners.

Asked By Malcolm Taylor | May 30 16
0 Answers
6 Answers

Log home DER Ideas?

I am a long time reader of GBA and, as a result, would not generally even go near a log house if I was interested in energy efficiency. That said, I find myself considering one due to its location, location, location. Given that, I would like to get some opinions about the best ways to go about retrofitting the house so it is at least reasonably energy efficient. Cost counts, so 'tear it down' options aren't all that helpful to me.

Asked By Rob Shuman | May 31 16
4 Answers

Is R-1 fan-fold insulation cost-effective as vinyl siding underlayment?

I am installing vinyl siding on a home in Pittsburgh PA as part of a HUD financed project. As such, HUD has supplied the specs. The requirement is for R1 fanfold followed by Tyvec. I think that the principal function of fan fold has traditionally, pre-house wrap, been to limit air infiltration (not provide R value), a function that is in this case served, redundantly, by the by the Tyvec.
There is almost no wall insulation and no plans to install any soon but there is adequate attic floor insulation.

Asked By Thomas Rydle | May 29 16
2 Answers

Retrofitting insulation: heat loss/gain where ceiling meets the wall

Hello all,

As part of my efforts to air seal and insulate my home, I just purchased a new FLIR infrared camera. First, what a cool tool for an energy nerd! It has instantly identified areas of the home on which to focus.

Asked By Brian Gray | May 31 16
9 Answers

Building an energy-efficient metal building

We are in the process of planning a metal pole barn used for manufacturing. We need to have metal panels on the inside (or similar) for wash down. We currently have a similar metal pole barn which is not energy efficient. What is a good way to make better use of the insulation / materials to make the building as energy efficient as possible? We also need to maintain a constant temperature of 55-65 degrees if possible.

Asked By Becky Parrish | May 30 16
31 Answers

Exterior rigid foam and re-siding project

I'm seeking input and opinion. I'm looking to re-side with the dread vinyl (need the low maintenance for my two story house). My 40 year old post and bean house has interior sheetrock, 3.5" of fiberglass batt insulation with kraft paper, rough cut full 2x4 studs on 24" centers, plywood sheathing (I think 5/8"), paper (a mix of Tyvek and felt), and cedar shingles. Shingles and paper will of course be removed, sheathing inspected in the process. I'm in zone 6.

Asked By Howard Gentler | May 2 16
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