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!


28 Answers

Wall moisture monitoring

I'm diagnosing a tricky moisture issue. Part of the process has involved the use of wall cavity humidity and temperature probes. I have some data and I'd like to "peer review" some of the findings in broad strokes.

First off, this great article got me thinking:

http://www.greenbuildingadvisor.com/blogs/dept/musings/when-sunshine-dri...

Asked By Rob Simpson | Mar 6 17
3 Answers

Modifying Existing ICF Walls

We are considering purchasing a house built completely with ICF walls. Our purchase is predicated on being able to expand windows in two areas and lengthening a current window area to install french doors to a deck. The expansion of the windows would involve removing the wall between two windows and installing a wider three panel window.

Is this possible with ICF construction. If so what are the key things that must be considered in making these modifications.

Thanks

Asked By ledICF | Apr 22 17
3 Answers

Insulating under a raised floor

We are planning to build a timber-framed raised floor in one section of our house. Currently this section is 1-2 steps (7-14") below the main level of the house, and is slab on grade. Long ago this was a garage.

We live in central NY, climate zone 6.

The 1970-s vintage slab is totally uninsulated to the best of our knowledge. We will add a plastic vapor barrier above it before placing the raised floor framing.

Asked By David Hollman | Apr 15 17
24 Answers

Slim duct mini-split concerns

Hello, I've been getting all sorts of conflicting advice about using slim ducts. House is new construction in Massachusetts. second floor has three smallish bedrooms, about 600 sq ft in total. Heat and cooling load calcs support using an 18k slim to hit the three bedrooms, which aI have a contract with a firm to install. However, a couple of other firms have stated adamantly that the cfm rating of the unit is too low and we won't be happy. Thoughts?

Asked By George M | Apr 18 17
12 Answers

Choosing and balancing R-values

We are in Minnesota (Zone 6a). The home is an "L" shaped, 2200 sq/ft single level, slab on grade with a 28'x40' attached garage making the "L"

I'm looking to nail down the R-values of the wall, ceiling and slab. If we do a 10" double stud wall with dense pack cellulose (R30) and 4" of EPS (R20) for the FPSF...what should we aim for in the ceiling? Is there a formula or rule of thumb to follow to balance these?

We are thinking 8/12 pitch gable roof, 1' energy heel, and scissor trusses (3/12 interior pitch) over the 26 x 34 living room/kitchen/dining room area.

Asked By Scott K | Apr 20 17
4 Answers

Question on vapor retarder on interior dividing wall

Hiya,
First off, thanks to the many that respond to questions posted by us less experienced folks! I have learned a great deal from this site so thank you.

Asked By James Culbertson | Apr 21 17
8 Answers

Heat build up in Florida garage

I friend of mine in Florida, zone 2A is trying to reduce the heat build up in his attached garage. He has a tiled, hip roof. I think he has soffit vents but no roof venting. There is a decorative half moon in a small gable above the garage door that maybe could be used as a gable vent.

He is looking at insulating either the garage ceiling or roof. He also mentioned a radiant barrier.

Being from the north, I suggested venting to let the heat our rather than insulation. What do you think would be the most cost effective and efficient way to help keep the garage cooler?

Asked By jim sweazey | Apr 20 17
7 Answers

2/3 1/3 insulation rule in roof

Old build with flat wood deck on 2x13s. 4 inches Batt in joist space.(R12) 2 inch air space above batt insulation under wood deck No external vents into air space Adding polyiso on top of deck R 28. Before adding the polyiso can/should we put a separator sheet or vapour barrier on top of the wood as there is more than 2/3 the insulating value above the deck There is a poly vb above the drywall ceiling below e joists.

Asked By UBSC | Apr 19 17
27 Answers

ERV selection

I've been reading, reading and reading about the various ERV options. Once I think I've narrowed it down, I read a new article or a new model has be released. What is the latest thoughts on the ERV market ranking them from best and also value?

Asked By Seth Holmen | Mar 26 17
4 Answers

One more question about rainscreens

When using a 3D rainscreen material like House Slicker, Delta-Dry Stucco & Stone, or Sure Cavity behind stucco, you need something between the stucco and the rainscreen material to keep the stucco from clogging the channels for drainage and air. Some of these materials come with a pre-bonded fabric to do this, whereas you would otherwise put something like a layer of felt on top of the rainscreen and behind the lath and stucco.

Asked By Domenico Perrella | Apr 20 17
Register for a free account and join the conversation


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