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

SHGC of north-facing windows?

I'm beginning the search for windows for my new home in Detroit, CZ5. South windows will have a high SHGC. West windows will have a low SHGC. The east windows get summer shading from a large oak tree so will have a high SHGC. My question is about north windows. Of course they won't be subjected to sunlight, but my first thought is that a window with a low SHGC will better reflect indoor heat back inside? I would prefer to be wrong because high SHGC windows let in more light.

Douglas Higden

Asked By Thrifttrust | Jan 13 18
9 Answers

Constructing a ceiling service cavity?

My plan includes a ceiling service cavity. The primary air barrier will be the top of the service cavity, the interior visible ceiling will be the bottom. Is there any reason that drywall can not be used both places? My 3" tall service cavity will be framed by a lattice of flat wise 2x4s, consisting of an upper layer perpendicular to the trusses and a lower layer parallel to the trusses all screwed together..

Asked By Jerry Liebler | Jan 15 18
6 Answers

Rainscreen for vertical cedar siding?

Hi all,

My builder is concerned about all the trim around my remodel due to my wish for 4" tongue-and-groove western red cedar (WRC) vertical siding. I will be mixing things up with about 1/3 of the outside coverage with WRC shingles so the product depth is not an issue.

Asked By David Flinn | Jan 12 18
1 Answer

Vinyl Windows with Synthetic Stone (2)

I posted this question last week, but it appears it was closed. We have Vinyl Windows installed, some with integral J Channel and some with Brick Molding and integral J Channel. On one wall of the home, we plan to instead install synthetic stone. I have been researching how best to use these windows with the stone.

I have contacted the stone manufacturer, and they had zero advice to offer. I also contacted the window manufacturer, and they have been no help either.

Asked By Kathleen J | Jan 15 18
8 Answers

Layout for ducted minisplit?

My house's floor plan has too many partitions to depend on comfortable heat distribution with ductless so I'll take the slight efficiency hit to use duct ed distribution. The plan is to keep the ducts inside the "conditioned" envelope and very simple and all in the ceiling service cavity, both supply and return for the air handlers. My house is a rectangle with the long side running east to west. A central hallway divides the north and south areas. My proposed layout uses two air handlers, two zones, one "bedroom" zone on the east and a "daytime" zone on the west.

Asked By Jerry Liebler | Jan 13 18
74 Answers

1952 Cape Cod


First-time poster. In the past 2 months, I’ve read a hundred or so GBA articles and comment threads; I’ve been amazed by the expertise and generosity of the community. I’ve also read extensively at buildingscience and finehomebuilding -- I’m new to but very interested in building science. Here’s why:


Asked By Emerson W | Dec 11 17
41 Answers

Region 5 below grade basement insulation techniques with intention to finish

I've probably read most or all of the articles on the subject 5-6 times over, but am still left with many questions as the advice can quickly change as the circumstances do, and it's difficult to keep track of all these factors.

My goal is to finish my below grade basement in 18301 Region 5. Cape cod style home built in 1968. 954 sq ft basement.

Asked By Ryan O'Rourke | Nov 19 17
1 Answer

Insulation the basement joist parallel with basement wall

There is a lot of information on how to insulate basement joists, but it's hard to find information about insulating the last basement joist that runs parallel with the foundation wall on the gable ends. Does the basement joist along this side of the house also require rigid foam or spray foam insulation?

Asked By Andrew G | Jan 14 18
0 Answers

Why your minisplit is likely not "modulating" at all

In other posts I've made observation of specified "capacity reduction" of several hyper heat like systems.
Those observations were all based specifications, which are all at 47f. I observed that most offer a 1/3 ratio. some offer a 1/9 or 1/10 ratio. I found this graph of constant speed capacity.
This dramatically alters how we must interpret the specification as outside temperature changes. !/3 capacity ratio @ 47f will maintain constant output. NO MODULATION.

Asked By Jerry Liebler | Jan 13 18
1 Answer

Air sealing an old brick building

I’ve been reading with interest the posts on weatherizing old brick buildings, but I still have some specific questions I hope someone can answer.
I have a circa 1837 brick federal with double wythe walls in central Vermont. The bricks are hard fired with tight mortar joints and moisture from the outside is relatively well controlled. Exterior walls are strapped with 5/4” planks supporting the lath and plaster. Interior walls are the same 5/4” planking with lath and plaster on both sides.

Asked By duanegormanbuilder | Jan 13 18
Register for a free account and join the conversation

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