Q&A: A Forum for Green Building Experts and Beginners

[Click map to enlarge]

Please register for a free account or sign in to ask and answer green building questions.

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!


3 Answers

Crawl space insulation questions

I’m going to be converting my crawl space to a sealed, conditioned space. The concrete block walls will be insulated with rigid foam. I’ll be using TherMax, as I understand that unfaced rigid foam does not meet the ignition barriers of the IRC. I am also planning to use spray foam to air seal and insulate the rim joists (per Fine Homebuilding No. 189 , September 2007). Interestingly, I’ve never seen any discussions about ignition barrier for the foam for the rim joists. What’s the story here?

In Building Code Questions | Asked By Michael Hansen | Nov 24 12
10 Answers

A new video: Joe Lstiburek talks about crawl spaces

Why is there rain dripping down from the fiberglass insulation in my crawl space ceiling? Joe Lstiburek explains why in this video.

In General questions | Asked By Martin Holladay | Nov 23 12
4 Answers

Duct location, unvented attics

In the Building Science America series unvented attics are recommended; "as long as they have airtight ceilings and the ductwork is not in unconditioned space". So how do you put in ductwork in conditioned space? I don't really want to use spf around the whole ductwork. Burying it in FG or cellulose doesn't keep it from causing condensation when it carries the air conditioning. Where is the ductwork to be placed?

In Energy efficiency and durability | Asked By Michael McKinley | Nov 24 12
1 Answer

I have my existing block wall in my basement and existing drywall I added furring strips and put drywall on block part.

What can I use to connect them. The new drywall sticks out about an inch more that the original
drywall

In General questions | Asked By Wayne Studer | Nov 24 12
2 Answers

Can I get healthy air quality using ICF forms?

I am new to building and live in SD. I want a home with good healthy indoor air quality as I have sensitivity issues. Spray foam is out. I am thinking of using ICF forms for the basement and 1st floor in a ranch style home. Cover the walls with sheet rock and insulate the attic with cellulose. Using a HRV system does anyone know if there would be any off gassing problems with the ICF?

Also, I read something about embodied energy and ICF forms. Can you explain this to me.

Thank you,

In Green products and materials | Asked By Kami Kline | Nov 23 12
1 Answer

Gaps in exterior foam - how to insulate underside of roof?

We're finally getting ready to insulate our roof, & after many hours of research have been unable to come to a consensus on what type of insulation to use. We are in climate zone 3 (central AL). This is an unvented cathedral ceiling, 12/12 pitch, & once finished will have sheetrock installed on the underside of the rafters (no can lights, etc). Currently the roof consists of:

2"x10" rafters on 24" centers,
1/2" OSB,
30lb roofing felt, with Ice & Water Shield on the ridge & in valleys,
1.5" foil-faced polyiso,

In GBA Pro help | Asked By Jessica Akau | Nov 23 12
1 Answer

Roof venting

We are building a 3/12 shed roof with parallel trusses North of Ottawa (zone 6-7). The roof is sloping to the South. We're wondering about potential for venting problems during winter with North and NE winds, as we think the wind catching the North wall will disrupt the normal venting of the roof. The site is fairly protected but these winds will blow on and off throughout the winter.

In General questions | Asked By jessie pratt | Nov 23 12
1 Answer

How to insulate unvented attic with foil faced rigid foam in 6 inch bays?

Hello,
Im currently remodeling my house in southern california. Im interested in building an unvented attic since all my HVAC equipment and ductwork are in the attic. In addition, we've had rats and mice nesting in the fiberglass insulation before we tore it all out. This is a single story, 3200 sqft ranch house that will have quite a few vaulted ceilings. With that in mind, what is the best way to use foil faced rigid insulation to create an unvented attic?

Option 1: 5 inches of JM AP foil-faced polyiso screwed directly to the undersides of the rafters and foamed and taped to air seal

In Green building techniques | Asked By andrew shu | Nov 22 12
1 Answer

Attic trusses - insulation question

Followup for clarification on at ICF home with attic trusses. I do plan to insulate the attic truss floor for two reason. !st is for noise reduction and the other is that this area will only ocassionally be occupied and will have reduced temps most of the time. Can I get away with spry foaming the roof trusses soffit to soffit with 2" and then putting in batt insulation to fill the cavity. I do plan to very soon finish this area so do I also need to insulated the side walls of the room if the rafters are already filled with insulation.

Jim

In General questions | Asked By Jim McKay | Nov 22 12
0 Answers

Roofer in Central Vermont needed

I have asked questions in the past about "ag style" metal roofing with ice and snow shield installed under it with an air space for ventilation for a school and gotten good feedback. Now I would like to go the next step to finding a roofer who could install such a roof in the Rutland, VT area. All the roofers I have spoken to immediately say... standing seam only- no discussion. Are there roofers in this area of the world with more open minds? Anyone to suggest? It is a 6,000 sqft building.

In GBA Pro help | Asked By Adrienne Raymond | Nov 21 12
Register for a free account and join the conversation


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