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!


6 Answers

I am thinking of an unvented cathedral ceiling

Hi. I am thinking of an unvented cathedral ceiling. Living in Hazelton, BC (Zone 4A, I believe), and would like advice on my proposed insulation plan. Staring from the underside: vapour-retarding paint; sealed gypsum board; 3/4" strapping; 2" or 3" Roxul board.

I would like to achieve at least an R50.

Asked By Mike Tomlinson | Jun 24 16
3 Answers

I'm chemically sensitive and the neighbor uses lots of pesticides that make me ill

Hello. I own a small 2 story semi-detached home, 1024 sq ft in all. I'm chemically sensitive and the neighbor uses lots of pesticides that make me ill. I would like to keep these VOCs out. Air purifiers have not worked for me.

Asked By Brenda Koehlert | Jun 24 16
4 Answers

Footing to foundation capillary break

Can a regular exterior latex paint we used for the capillary break between the footing and foundation, if one puts on a couple of coats. This is in a very dry climate, and the likelihood of any foundation water is almost non-existent. This is merely an extra added precaution. Footing poured today so we have the weekend to paint :-)

Thank you!

Asked By Steve Wilson | Jun 24 16
2 Answers

Double stud wall with a mid-wall vapor retarder

I'm starting the process of building a double stud house in the Milwaukee,WI area and am looking to find more information on double stud walls with plywood on the outside of the inner wall. I have already searched this site, but I wanted to see if I missed any articles/Q&A blogs that provide information on this wall system. I wanted to provide the builder with some information on why I chose this particular design. Any information/documentation links would be greatly appreciated.

Asked By Brad Depies | Jun 24 16
5 Answers

Roof buildup - Zone 4B

Curious as to this Shed Roof Build-up:

EPDM Roofing
2" Thermax Rigid Insulation Board (R-13)
Roof Underlayment
5/8" CDX Sheathing
2x12 DF#1 Rafters @ 24" o.c.
Layered Roxul Batt Insulation (R-46)

Any issues or potential problems?

Asked By Peter L | Jun 24 16
14 Answers

Now that outsulation is "out," what next?

Zone 5, Northeast US, two story residential home. Planning for exterior "true" cement stucco and areas of stone and brick veneer. After many permutations and consults, I have concluded, NO on outsulation. Two engineers, one architect, one stucco contractor, one mason and a few general contractors all said the same thing. The same thing that a while back was told to me here on GBA by Martin, "it is not proven and risky, be very careful".

Asked By Sal Lombardo | Jun 20 16
11 Answers

Geothermal vs. air-source heat pump

I have researching and getting quotes on hvac for a while now.. It is getting to crunch time.
Well insulated, tight house.

All three quotes include:
3 units, 3 air handlers, each zoned 3 times. Rigid Trunks and short flex runs.

option A. Carrier 18seer 25vna08... 5 stage. ( I don't like the potential harmonics problems of their greenspeed)

option B. Lennox x25 top of their line variable.

option c. Waterfurnace 7 series geothermal units. horizontally drilled ground loop.

Asked By Dean Sandbo | Jun 22 16
3 Answers

What should I use on the exterior of a dormer?

Climate code 5, old wood siding removed, 1/2" fiberboard in place, no insulation in the 2 x 4 walls. I will be installing vinyl siding. Mostly concerned that the dormer breaths and drys properly and not concerned with adding any R value. Thank you for your time.

Asked By Kris Burkett | Jun 24 16
7 Answers

Seeking insulation recommendations

I work with Habitat for Humanity in upstate SC (zone 3 - warm-humid), and we are researching practices to improve the energy efficiency of the houses we build.

We have been insulating the attic ceiling with blown-in fiberglass but are leaning towards insulating the whole building envelope now (cathedral ceilings and sealed crawlspaces).

First, is it cost-effective to put the HVAC unit and ductwork in the conditioned attic rather than the crawlspace?

Second, what type of insulation should we use in the roof?

Asked By Dylan Hillman | Jun 23 16
68 Answers

Why haven't steel-framed homes become more popular?

I am in the planning phase of building a home in the NJ-NY area, Climate zone 5. As I investigate my options; SIPS, double wall stick 2x4 wood, 2x6 wood, ICFs, CMU, Larsen trusses, etc.. and the myriad of permutations to insulate each one (spray foam, cellulose, hybrid batt & flash, exterior rigid foam/iso panels, etc....) I came across STEEL. My goal is as high R-value as I can get within reason $$, with hope of upwards of R-30 final values. That said, I need some objective input.

Asked By Sal Lombardo | Dec 27 12
Register for a free account and join the conversation


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