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13 Answers


We have a new construction home, less than one year old. Windows are the type that slide inward to clean, etc, vinyl, double pane. We have had temps drop below zero a few days in the past couple weeks. Whenever it gets below 0 degrees, we get condensation. Not the entire window, but along the bottom edge of the interior window, the space in between the bottom fixed window and the top slider, and in just a few windows it will frost in the bottom corner of the frame. Have checked humidty, and we run about 25%. Also have a call into the window rep, but haven’t heard back yet.

In Energy efficiency and durability | Asked By Kathleen J | Jan 2 18
2 Answers

Application of 2/3-1/3 rule when rigid foam is vapor barrier

I submitted a question a couple of weeks ago: "Rigid Foam Between Walls" in response to which I received numerous very helpful answers. Thanks again.

In General questions | Asked By David Williams | Feb 14 18
3 Answers

Bungalow porch: Should we insulate the ceiling?

We are building a Craftsman Bungalow in Farmington, Maine and the house has hip roofs and an open front porch. The porch roof is integral with the main house as it is shown in the attached figure.

My question is: Should the porch ceiling be insulated with a vapor barrier like the interior ceilings? We are planning on using Roxul insulation with a vapor barrier in the main house to get us an R-50 rating.



In General questions | Asked By User-6980234 | Feb 14 18
1 Answer

Whole-house fan in cathedral ceiling design

I'm building in climate zone 6B and I'm trying really hard not to put in AC. Our house is at 7000ft but we still get a few weeks of hot temperatures that are bearable during the day but are too hot for us to sleep at night. My thought was to do an air flush in the evening using a whole house fan.

In Mechanicals | Asked By Steve Mackay | Feb 13 18
5 Answers

New outbuilding, mold, crawl space encapsulation/ventilation plan

I'm building a 190sf art studio/office in Zone 5B (Central Oregon, drier/sunnier eastern side of Cascade range, sandy/volcanic ash soil, 24" frost line, ground freezes here). It has a one-year-old vented crawl space that developed mold beneath the plywood subfloor and I-joists. It sat with no roof and no ground moisture barrier through last year's snowy winter. Last Spring, I scrubbed the mold off with diluted bleach and spread 6mil poly over the ground, but did not attach the poly to the stem wall or seal up the vents.

In Energy efficiency and durability | Asked By KevinEJ | Feb 13 18
7 Answers

Recommendations on HVAC Design

Because local HVAC contractors typically oversize and aren't apt to land on the ideal solution for high performance homes, I am considering analysis by a third party like Energy Vanguard for my cold climate ductless heat pump system:


I would like to get some feedback on services like this and any recommendations of alternatives to them. I was quoted $900 for:

-Manual J room-by-room heating and cooling load calculations
-Manual S system specification with Diamond System Builder report for Mitsubishi

In Mechanicals | Asked By J M | Feb 13 18
21 Answers

Radon is 9.3 pCi/L even after radon mitigation — Is this OK?

Hi. I am having elevated ( 9.3 pCi/L) radon after mitigation done. I have an encapsulated crawl space ( insulated, air sealed, dehumidifier ) with piping running under vapor barrier-which terminates to an outside radon fan connected with a 4"PVC pipe. Would like to find out if it's Ok to install drainage ( perforated black pipe) piping under vapor barrier ( in encapsulated crawl) for radon mitigation. The piping is spilt off of a main trunk ( no continuous circle) to different sections under the crawl.

In GBA Pro help | Asked By Hotandhumid | Jan 22 18
6 Answers

Corrugated metal over mineral wool

Hi, I am looking for ideas for installing vertical corrugated metal over Roxul comfort board.

A bit more about the project:
Zone 5B,
2x6 @ 24" OC walls insulated with Roxul batts (R-23),
plywood, wrb, and
2" Roxul Comfortboard (R-8), corrugated metal siding running vertically.

Do I need to install vertical furring a layer of horizontal furring to attach the corrugated panels to? Can the metal be attached directly over the comfortboard?

Thanks for any thoughts/ ideas.

In Green building techniques | Asked By Stacey V | Feb 6 18
12 Answers

250 cfm differential with radon fan: Why?

Hi. I am working on a continuing problem, and hope to get the advice from the smart minds on here to figure out why we have are having both indoor humidity fluctuations and elevated radon ( GBA links to both topics attached below). Trying to solve both humidity fluctuations and elevated radon ( 9.3 pCi/L) with radon fan running. I did close up the 3 small HVAC supply damper vents as suggested in the previous post ( see link below)... thanks! However, we are still having pressure/cfm differential with the radon fan running, based on blower door test done yet again.

In General questions | Asked By Hotandhumid | Feb 12 18
5 Answers

1950 building — bare block walls, no insulation, no drywall — 1 1/2" room to improve?

Northern Ill location -8 " block bare except paint inside and out. Apartment 2 bed forced air nat gas heat New anderson double hung well sealed.
Will put treated 2x2" interior frame to put conduit for new circuits--only 2 circuits now -kitchen and everything else. flat roof with 2x10 insulated. So do I go plastic vapor barrier then 1 1/2" sheet foamboard between studs? or just foam board or building wrap over or under foamboard. No AC.

So now condensation point is in block wall and has been forever. If I move it in -will I create a water making machine?

Any Ideas?

In Energy efficiency and durability | Asked By Scout159 | Feb 10 18
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