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!


10 Answers

Heat pump recommendations (central system)

Hello Gents,
I have been lurking here, pretty much since I bought my first new home, (11 years ago) and realized how little I knew about this huge purchase.
It’s a 1650 sq. ft. two-story house, in Montreal, Quebec, (zone 5a) built in 2007. It has central heating, electric furnace with the original 2.5 ton heat pump, which has just let go.

In General questions | Asked By Sean Herbert | Jun 11 18
5 Answers

Exterior rigid foam

I'm soon residing my house and plan to incorporate 2" of exterior rigid foam (EPS). Is it a no-no, or is it okay to adjust the typical order of things by having 1" of EPS, then strapping over that, and then a second layer of 1" EPS. This makes for a 3/4" space that is not typical. But is it a problem?

Thanks for any input/advice.

In Energy efficiency and durability | Asked By Howard Gentler | Jun 11 18
1 Answer

Flood protection bags for HVAC equipment

I saw these on the RDI site. It sits under your furnace or hot water heater and rolls up in case of flooding to protect the equipment. Anyone used one?

http://www.resilientdesign.org/a-novel-product-to-protect-water-heaters-...

In Mechanicals | Asked By Scott Wilson | Jun 11 18
7 Answers

Vapor retarder/barrier in an insulated above-garage floor

CZ6A, Ottawa ON

Our build will have a bedroom that extends out above the un-insulated garage. The floor will be 14" deep I joists and will be dense packed with cellulose (R50-ish). I'm planning to use Intello on the interior walls as a vapor retarder.

Question: What should I do for a vapor retarder/barrier above the garage?

Do I use a vapor retarder on top (between the floor sheething and joists), underneath (between the joists and the garage ceiling drywall), or is a totally different approach necessary? Should I be using a vapor barrier instead, like 6 mil poly?

In Energy efficiency and durability | Asked By Lance Peters | May 10 18
9 Answers

Insulating top of basement slab - Is moisture still a problem with a barrier?

Is insulating the top of a non-walkout basement slab floor in climate zone 6 really valuable if the slab has a moisture/vapor barrier beneath it? Goal is carpet on top for most to the space. What happens in the event of water flooding from a toilet or clogged drain?

In General questions | Asked By BobTheWeekendWarrior | May 4 18
3 Answers

Best paint that reflects solar radiation?

I have a white stucco house that is poorly insulated and when it receives sunlight in the evening, the walls get quite warm as measured with an infrared thermometer. It has R-7 insulation in the 2X4 walls so there is something but not a whole lot. Anyway, I wanted to know if there is a good paint that can reflect solar energy.

http://solutions.3m.com.tr/3MContentRetrievalAPI/BlobServlet?lmd=1370888...

In Green products and materials | Asked By Dave R | Jun 10 18
6 Answers

Vented open-cell cathedral ceiling

Good afternoon - What are the draw backs to venting an open cell spray foam cathedral roof assembly?

To note - the original roof assembly was design was with R30c kraft face batt insulation. - The framing inspector is concerned that I have a double vapor barrier between the kraft face and rigid XPS.

In Energy efficiency and durability | Asked By Bob Harshman | Jun 11 18
3 Answers

Insulate stud cavities with the possibility to install exterior foam in the future

Hello!

I am planning the remodel a 1920's craftsman and wanted to get feedback on how to install the insulate in stages.

The building is a 1.5 story craftsman with a basement. The basement has a 2' cripple wall. The wall framing is 2x4's. Exterior to interior the layers are hardiboard, 1x12" lapped plank sheathing, 2x4s 16" OC with empty cavities, and then lath and 1/4" plaster walls. The roof is an A frame with 2x8 rafters.

I live in climate zone 4C.

In Energy efficiency and durability | Asked By dgardner88 | Jun 11 18
6 Answers

Mitsubishi multi-zoned system for passive house too much?

I'm building a 4 bedroom passive house with about 3,200 sqft of conditioned space including a home office and a 2 car garage and 1 car garage (workshop) totaling around 800sqft. I would like to use an 8 zone mitsubishi system with horizontal ducted indoor units. Zones will be assigned to each bedroom (zones 1-4), the home office (zone 5), the main living area (zone 6), the 2 car garage (zone 7), and the worshop (zone 8).

I have a few questions:

In Mechanicals | Asked By Mike AbiEzzi | Jun 9 18
3 Answers

Roofing question: Do I NEED 5/8" plywood decking under a 50-year steel roof?

Specs:

House 6:12 pitch, garage 3.5:12 pitch

Trusses 24" OC, 2X6 top cord (solar ready). Climate zone 6A, mid to low snow load.

In GBA Pro help | Asked By Mai Tai | Jun 10 18
Register for a free account and join the conversation


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