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!

0 Answers

an up-date to encapsulating the crawl space

just wanted to say thank you to Martin and the detailed information on this web page.....and give an up-date on too much moisture in the crawl space.
I started off with a 1000 sq. ft, vented to the outside, crawl space. It averaged 3' high, there was no insulation on the concrete walls and the vapor barrier on the dirt was 6 mil with plenty of gaps.

Asked By nepal | Jan 23 18
2 Answers

How to insulate and finish basement when there are signs of efflorescence?


I am re-finishing/insulating my basement in a 1930 home in Zone 4 (Pacific NW). I am planning to do it as follows from foundation to interior which meets local building code: Basement Concrete Foundation Wall > 1”XPS Rigid Board(Pink Owens Corning) > 2x4 Studs against the XPS > ROXUL insulation in stud cavities > Sealed Poly Vapour Barrier > Drywall.

There is evidence of white efflorescence on the basement walls indicating that there may be or has been in the past moisture seepage. There have been no flooding events. Being a 1930 house, the foundation is not waterproofed.

Asked By J2D2 | Jan 21 18
0 Answers

Insulating a house with 2x4 framing using exterior rigid foam

Planning extensive remodel on a 1961 home. I’m taking interior down to studs and replacing siding/roof/windows, so I also want to take the opportunity to make it as energy efficient as possible.

Current House:
-Rectangular ranch style with 2x4 trusses running the entire length of the house
-Vented attic with ~3 ft peak height so it's lowish pitch and shallow eaves
-Exterior walls are 2x4
-Climate Zone 5. Calls for R20 walls and R38 roof but I’m all for going above it :)

Planned wall upgrade:
-Batts between 2x4 studs
-2-4” of XPS outside of sheathing
-Metal siding over XPS

Asked By jetlaggy | Jan 23 18
17 Answers

What should I replace my heating and cooling system with?

Hi all,

I'm looking for advice on the 'best' solution to my heating and cooling (and hot water)

- Zone 5b
- Loads from coolcalc and manual D/J
Heating loads
- Main house: 28k to 36k, 900 cfm
- Sunroom addition (can be closed off): 8k, 150 cfm unducted not planning to directly heat (current situation)
- Office addition 5k/3k, 180 cfm. Unducted, can probably be heated via staircase.

- Main house cooling load: 24k to 36k, 1200 cfm
- Sunroom addition: 8k, 450 cfm unducted not planning to directly heat (current situation)

Asked By Jill D | Jan 17 18
0 Answers

Envelope for garage under duplex

Planning a PGH, all electric, duplex on a small lot in Zone 6 Whitefish, Montana. Lot size/setbacks dictate that the two-story duplex with shared wall sit on top of the two-car garages. A scan of info from this site would indicate the garages be designed within the thermal envelope, as opposed to the envelope border being the ceiling of garage/floor of first floor. Any suggestions for a less expensive way to design the envelope than including the garages?

Asked By Dave McAlpin | Jan 23 18
3 Answers

Ventilation in old house that will soon get new heating-cooling system

I am a homeowner interested in ventilation and air quality, and I'm hoping for objective feedback on my situation (the HVAC companies have been helpful, but I'm skeptical of some of the air-quality machines they've proposed).

I have a leaky 1920s home (four people, 2,000 sq ft including basement and three bedrooms, 2x6 exterior walls) in the Pacific Northwest on the water (comparatively mild winters and summers, humid), if that information helps.

Asked By GWVM | Jan 23 18
0 Answers

Stone Veneer following rain

Out of curiousity, does stone veneer or Synthetic Stone tend to stay wet longer? Noticed a neighbors house with some Synthetic Stone certain sections still look wert almost 18 hours after rain. Granted, the temp also dropped and we had zero sunlight today to help dry anything quickly.

Asked By Kathleen J | Jan 23 18
19 Answers

Header hangers vs. jack studs: Thermal bridging?

Advanced framing articles all seem to advise the use of header hangers instead of using jack studs. The idea is, less wood and more insulation in the wall, and better the thermal performance.

Has anyone studies whether the thermal bridge of a jack stud is better or worse than a header hanger? A jack stud is very large by comparison, but a header hanger is a relatively heavy gauge piece of steel that bridges right from sheething to drywall.

Beyond the thermal bridge, could a cold spot behind the drywall cause moisture issues or condensation on the interior surface of the wall?

Asked By Lance Peters | Jan 21 18
3 Answers

Kitchen Hood

I’m in BC. I’m trying to figure out if a kitchen range hood is compulsory as I have been led to believe. I tried reading some of the government building code docs but they are not written in plain English and I really couldn’t figure out what they were burbling on about.

Asked By TracyPTM | Jan 23 18
7 Answers

BEopt results

Tried using BEopt for my house and the results were a shock, somewhat. I live in Zone 4 in Maryland and was concentrating on the things I know will be occurring in the near future, attic insulation and wall retrofit insulation.

According to BEopt, the biggest insulation bang for the buck was the wall insulation. Putting in R13 of cellulose with Grade 3 installation produced a drop of about 500 therms per year. (I assumed Grade 3 installation was appropriate, since 1) it will be a retrofit and 2) I have a severe lack of faith in contractors.)

Asked By Jeff Towson | Jan 22 18
Register for a free account and join the conversation

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