Q&A: A Forum for Green Building Experts and Beginners

Q & A Instructions

[Click map to enlarge]

The GBAGreenBuildingAdvisor.com web site has a wealth of articles on a wide variety of construction topics. Before posting your question, you may want to check out the articles on this page: How To Do Everything. You just might discover an article there that provides the information you seek.

Please register for a free account or sign in to ask and answer green building questions.

If you want to post a question, 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!


4 Answers

How bad is MDG?

My builder installed MDG from TLC Mouldings. The specs call for MDF with
no added formaldehyde, but I did not remind him. Argh. How bad is
regular MDF? Should I rip it out, coat with an absorbent primer, move
to another country? My rater suggested heating the house to 80 degrees
for two weeks to cook the formaldehyde out. Thoughts?

In Green products and materials | Asked By Steve Knapp | Dec 10 13
30 Answers

Window condensation issue

I'm in the middle of constructing my home and have discovered a serious condensation / bulk water issue. First some background: We're in southern Maine. The envelope is a double 2x4 stud wall system 10.5" thick insulated with Roxul. Exterior air barrier is taped zipwall and interior air barrier is ADA with taped or gasketed seems and joints. No vapor barrier. We put in Intus Eforte UPVC windows.

In GBA Pro help | Asked By Brian Beaulieu | Dec 8 13
2 Answers

Wall assembly with XPS foam and stucco

I am looking for help with my exterior wall assembly. This is for a house with Stucco exterior and XPS foam. We are building a house in Climate Zone 3 (SF Bay Area). Required wall insulation here is R13, but I would like to do better and add 1 inch XPS foam to increase R value and eliminate thermal bridging.

I am confused about the appropriate wall assembly after reading several articles on GBA and other sites. Code requires "2 layers of Grade D building paper" over the OSB/Plywood.

Here are two wall assembly options I have in mind:

Option A:
1. Drywall

In GBA Pro help | Asked By Thomas Schulz | Dec 15 13
5 Answers

Are cupolas worth considering on a well insulated home for ventilation?

Are cupolas worth considering on a well insulated home for ventilation in the summer? In zone 5a there are some months where the day time requires some A/C and the night does not. A whole-house exchange of air would be nice around 8 o'clock at night, when the temps outside drop.

The idea would be to open up the cupola along with the first floor windows and allow the stack effect to exhaust the air. I guess it's the same idea as the whole house fan that pulls all the air out of the house and into the attic. We had one in our old house and it never seemed to work as good as the theory.

In Mechanicals | Asked By russell berenson | Dec 9 13
12 Answers

Insulating exposed rim joists

We are building a home in Maine where the basement won't be finished for some time. Besides loose fill insulation, what can I use on the rim joists that is fire resistant when left exposed.

In Energy efficiency and durability | Asked By tom ruben | Dec 14 13
2 Answers

Vapor barrier

I have recently purchased a three family home in Massachusetts. The house was built in the 1860's and has no insulation in the walls that I'm aware of. When I purchased the home the exterior had recently been vinyl sided and insulated with 3/4 inch insulation according to the seller.The house has a walk in attic that is not insulated at all, but the second floor apartment has had some insulation put into the ceilings. You can see the insulation in the ceiling from the attic.

In Green building techniques | Asked By Ronald Benoit Jr | Dec 16 13
1 Answer

I have a central air conditioning unit. Can I convert it to a heat pump and air conditioning?

I live in NY and can I convert my central air conditioning unit to a heat pump and air conditioning unit and if so how do you do it? Thank you

In General questions | Asked By vincent lomonaco | Dec 15 13
6 Answers

What is best treatment for the top of elevator shafts?

We do mostly home weatherization, but also get into frame and brick public buildings that have elevators.

Elevator shafts seem to be poorly insulated and air sealed at the top. Often they are just cement block or brick with a corrugated metal roof 6-8' above the flat roof. There might be 1" or 2" of foam board above the corrugated roof, but no where near R-39 or R-49 (Mass or Vermont). No air sealing whatsoever, so these shafts look & behave like chimneys, sucking heat out of the buildings.

In Building Code Questions | Asked By Robert Rueter | Sep 10 12
2 Answers

Stories and Half-Stories

We're getting ready to submit plans in Contra Costa County, California. It's a highly developed county, with no shortage of regulations and regulators. But we're having trouble getting clear answers to what seem like simple questions, such as "how many stories is this house?"

Zoning restricts us to 35' or 2.5 stories. Local code defines:
“Half story” means that portion of a building under a gable, hip or gambrel roof, the top wall plates of which on at least two opposite exterior walls are not more than three feet above the floor of such building portion.

In Building Code Questions | Asked By Nathan Kurz | Dec 13 13
2 Answers

Adding Henry Blueskin inside

I have a existing log home and would like to frame a wall inside in some areas to beef up the R-value. I am thinking of adding a layer of Blueskin, then studs and batts. So from outside wall would be" 10" log, Blueskin, batts (Roxul perhaps) and drywall or T-and-G boards. Seems the layer would stop air infiltration while being vapor permeable. Thoughts?

In Energy efficiency and durability | Asked By scott mangold | Dec 13 13
Register for a free account and join the conversation


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