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

Exterior foam installation details

Our house is 2x6 construction built in 1984 near Milwaukee, WI. Going from the inside out, drywall, vapor barrier, fiberglass insulation, EPS foam sheathing, and Cedar board and batten siding.

In Green building techniques | Asked By Kacey Zach | May 9 12
3 Answers

Which exterior sheathing is better?

Which exterior sheathing system would you recommend - Zip system with housewrap vs plywood with 3M 8067 tape and housewrap? The difference in cost is only $300. We are in Zone 5a, upstate NY. We are concerned about the long term life of the sheathing and what would happen if it gets wet (mold).

In Green building techniques | Asked By Elizabeth Kormos | May 9 12
1 Answer

How do I improve R Value and change to metal on my roof?

I have an older Pan-Abode home that has cathderal ceilings with minimal roof R Value. I would like to increase the R Value and lay metal roof over shingles. Does anyone have insight on the best way to do this?

In General questions | Asked By Laurence Bishop | May 8 12
1 Answer

Zip or Rigid Foam or Both (& HVAC)

Hello - we are building in Cincinnati (4800 sq ft). Our builder is a fiberglass batt person with no exposure to any of the techniques on the forum, but he's willing to try new things.

The house will be a 2x6 construction with 10ft first and 9 ft second. We have 2 questions:

In General questions | Asked By Guy Hocker | May 8 12
7 Answers

Exterior foam decision — IRC table 601.3.1 — and housewrap over foam

I am building an attached 3-car irregular shaped heated garage and trying to make it energy efficient but not break the bank. Some last minute roof changes during framing have made the attic area of garage usable space which will become a bedroom some day

I did a 4' ICF foundation because I want to heat the slab (partially by solar panels someday) there is 5" of high density EPS under the slab (craigslist bargain)
2x6 walls were necessary so the exterior walls would bear more on concrete rather than ICF foam.

In Green building techniques | Asked By tom fraser | Apr 12 12
16 Answers

Styrene and EPS/XPS rigid foam insulation

I just saw a report last night on ABC World news where they indicated that scientists have added Styrene, a component of EPS and XPS rigid foam, to a list of possible human carcinogens. Does it make sense to consider it still as a good option for reducing thermal breaks in wall construction or would a better option be to lean towards double wall construction? Same for its use as a foundation perimeter and sub slab insulation ... maybe less of a concern?

In Green products and materials | Asked By Milan Jurich | Jun 11 11
3 Answers

What is the smartest way to insulate a finished attic?

Hi. I am a newby on this site and am looking for advice on how to correctly insulate the living space in my attic.

I believe in a vented roof so I vented the rafter bays with 1" Dow Tuff R rigid insulation spaced 2" off the underside of the roof sheathing. It is sealed all the way down to the floor and it ends about 6 inches above the collar ties. I sealed all the edges with foam and I taped all the seams.

The rafters are 2x10 and the collar ties are 2x8. I live in northern New Jersey in IECC zone 4. The rigid insulation is R6.5.

In GBA Pro help | Asked By Randy Aubrecht | May 7 12
4 Answers

Are there concerns with having a fireplace in a home with spray foam insulation?

I'm building a home in southeast Alabama, and the general contractor mentioned that there are concerns about installing a fireplace in a home that is insulated with spray foam insulation. I haven't located any data on this topic; can anyone shed some light on this or point to a source for information?

Thanks.

In General questions | Asked By George Tarbox | May 7 12
1 Answer

Replacement windows

Older brick home in Virginia beach, Va. It has aluminium slider casement windows.

Removed old window. I found the wood rot around window frame, brick bottom and brick sides.

What should I do? Also, on the outside, the window sill is sloped toward the house as per a level.

I have pictures of this. Thank you.

In General questions | Asked By Paul Dobin | May 8 12
4 Answers

How is that a material can be both airtight and vapor permeable?

Can anyone point me to an answer that explains the physics? Obviously to be vapor permeable a material must have penetrations that are bigger than vapor molecules; why doesn’t air, driven by an air pressure differential, flow through the same holes? I’ve heard it said that the pores are big enough for H2O molecules but too small for O2; is that it? Or is it simply that the rate of air leakage is too low to matter given the grosser methods used to measure air leakage compared to vapor diffusion?

In GBA Pro help | Asked By Hayden Robinson | May 4 12
Register for a free account and join the conversation


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