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!

7 Answers

Best method for air sealing an existing tongue-and-groove (wood) ceiling? Sheetrock is out.

The Home is located in Zone 4 NC. Question #1 Any problems using closed cell spray foam on any

large cracks , in attic at ceiling plane. Then using blown in cellulose ?

Question # 2

Any best method for securing tongue and groove ceiling to prevent cellulose from pushing down ceiling ? Netting etc.

Question # 3

Thought of using Reclaimed Commercial Roofing foam board Fiberglass faced , using cut and cobble

at attic joist bays. Leaving small air gap from tongue and groove ceiling. My thought was it would

In General questions | Asked By Greenconfusion | Apr 13 17
9 Answers

Slab to foundation wall: Air Barrier and capillary break detail with interior rigid foam

We’re planning on insulating our basement walls with 2 inches of Thermax (foil-faced polyiso) rigid foam, installed with adhesive on the interior of the wall. We’ll also have 2 inches of XPS beneath the 4 inch slab, and would have these different types of foam connect right on top of the footer, similar to the detail shown at:


In Green building techniques | Asked By William Costello | Apr 12 17
4 Answers

Minisplit outdoor unit placement (with pictures)

I have a few options for install locations for my two 18K btu minisplits. My installer is willing to go with any location I want, however it is going to be cheaper and easier to go with options 1 or 2 since they have access to the crawl space.

For aesthetics, I would prefer to go with either options 1 or 2 as well. I just do not want to cause any issues with efficiency due to the units being too close. Also, the air conditioner in the picture will be gone as well.

What are your guy's thoughts? Thanks!

In Energy efficiency and durability | Asked By Justin Serr | Apr 11 17
4 Answers

Semi-controlled conditioned space?

As we move toward installing closed-cell foam in our attic rafters and gable walls, the choice has come up as to how much of the old fiberglass insulation under the attic floor we want to remove. Obviously it has to be taken out in the area where the roof meets the floor to enable an airtight fit by the foam. Ordinarily making this a conditioned space would entail keeping the temperature of the new space as close to the floors below as possible.

In Energy efficiency and durability | Asked By David Goldman | Apr 12 17
6 Answers

Cold Access Room - Gaps in Air Barrier

** Re-posting to the proper Q&A category **

Hi -

In Energy efficiency and durability | Asked By Joe Duchek | Jan 16 17
4 Answers

VOCs in cabinetry conversion varnish

Hello - we are building a home (Zone 4C) and I asked the cabinet maker for a data sheet on the paint they will be using. It is a Rudd conversion varnish with a VOC level of ~500 g/L (<0.1% formaldehyde by weight). That seemed high to me, so I looked up the maximum allowable in the U.S. for conversion varnishes, and it's 725 g/L. I also searched for the VOC level of conversion varnishes sold by Benjamin Moore and Sherwin Williams, and their VOC levels were comparable to Rudd. Should I be concerned?

In Green products and materials | Asked By Mike Dominic | Apr 12 17
1 Answer

Has anyone heard of the Complete Block Company?

I'm on the initial planning stages of the house I'm planning on building. So basically a lot of hours spent on GBA forums and scrounging information wherever I can get it.

My question is: Has anybody ever used these blocks? And if so, what was your experience?

In General questions | Asked By youngb556 | Apr 12 17
2 Answers

Insulation and air sealing around exposed rafters and beams

Our new build project with have exposed 4x8" Douglas Fir Beams cantilevering over the front and rear elevations of the property with a low-slope "warm" shed style roof. I've previously posted on the roof assembly and comfortable with our approach there.

I know that cantilevered beams penetrating the assembly is far from ideal, but it is what is so I am trying to come up with the best solution with some input from your kind selves. I can't seem to find anything in the articles so I've purely come up with the below based on a best guess.

In GBA Pro help | Asked By Quinn Sievewright | Apr 11 17
13 Answers

Working with tract builders

Regrettably it looks like I may have to pull the trigger on a new tract built home.

The dwelling will be your typical townhouse with a drive under garage and a rear two-story cantilevered section.

As I was saying, I really do not like tract builders because they can't control their subs but due to high land costs they're the only game in town unless one wants to spend over $750k for a custom home.

From my own experience with this design of home there are two what I consider typical failures.

In Project management | Asked By John Clark | Mar 2 17
12 Answers

What are your recommendations for re-insulating a home with 2x4 walls that has been completely gutted down to the studs?

I am in climate zone 6 in the Upper Peninsula of Michigan. The house was in terrible condition inside, so I bought it really cheap and am basically rebuilding the interior from the studs out.

The interior drywall has all been removed, so the 2x4 cavities are exposed. Three of the four walls will have modifications to window openings, so I need to take off the siding anyway.

What are your opinions between:

In Green building techniques | Asked By Jeff Martin | Apr 11 17
Register for a free account and join the conversation

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