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

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36 Answers
Exterior rock wool insulation with batts?

Hello folks,

First, I'd just like to say how thankful I am for the invaluable resource that is GBA. I spend A LOT of time reading the blogs and Q&A and I find that pretty much any question I might have has been covered here already. Though sometimes my understanding gets a little vague regarding certain details so I am hoping for some input on a potential wall detail.

Asked By Noah Byler | Jul 23 14
9 Answers
Cold cellar question

We are building a new home soon and I really want to include a small cold cellar to age a few beers and keep some wine cool in lieu of a beverage refrigerator. I also want keep our chest freezer (we buy full animals to process) in here to lower its run time.

Asked By Troy Stevenson | May 7 13
13 Answers
Attic ventilation questions

Hi Guys,

So after getting a $310 bill from the folks at Duke Energy last month, I decided it was time to figure out a more efficient way to cool our home. I've since asked them for their free energy audit to identify areas where I can save energy.

Asked By Jeff Lever | Jul 29 14
Answers
Multifamily wall sheathing pros and cons

Any folks out there interested in helping me out with a research study? It's an online study with 5 sets of questions and takes about an hour total. We are trying to understand perspectives on the pros and cons of various wall sheathing materials, especially for multifamily structures, and as it relates to green building. If you are interested, please contact me via emailat mary@deepblueinsight.com or call me at (404) 459-7100. Our website is www.deepblueinsight.com

You will be paid $300 for your time. We need three people to participate. Thanks.

Asked By Mary Elzey | Jul 30 14
6 Answers
Foil faced ISO over 3" closed cell spray foam?

Looking for an answer before I start this project. I live in northern MN. I had my attic spray foamed 4" behind knee walls, 3" in the living space. This is a 1 1/2 story with a non-vented roof. I want to know if its O.K. to use foil faced 1" rigid sheets to cover studs, foil facing down between the knee walls. I did plan on filling all voids and foil taping the joins. Then 1/2 sheet rock over the foam. Just want to make sure this isn't considered a double vapor barrier, and if this would be considered good construction.

Thanks

Asked By david chinn | Jul 27 14
13 Answers
Check my wall strategy?

We're about to begin framing on a new house in zone 6A (Minneapolis). From months of reading and following posts here, I've devised what I think is a wall/insulation strategy that will work. Does this look right, or are there any tweaks that could make it:
a) perform better (within reason; we're going after the "pretty good" model, not a Passivhaus)
b) more cost-effective
c) easier to build

The concept (inside to out):
- Drywall
- 2x6 stud wall
- Membrain or similar (6-mil poly if the inspector insists...sigh)
- 5.5" blown fiberglass cavity insulation (BIBS) = R-23

Asked By Joshua Wyatt | Jul 28 14
5 Answers
How can I remedy a cathedral ceiling with fiberglass batts in unvented rafter bays that now emits a strong musty odor?

Investigation revealed 3 problems: 1) no soffit vent; 2) insulation extending beyond the end of plastic rafter vents closing off the air channel up to the ridge vent; 3) no blocking above the wall to seal up the fiberglass. I've corrected the first two and caulked the ridge on the inside, but am unable to fix the blocking. The odor persists and I fear the fiberglass is contaminated with mold that the revived air flow won't be able to dissipate. Would pulling out the fiberglass (through the soffit to avoid major deconstruction) and filling the bays with foam work?

Asked By Michael Roland | Jul 25 14
18 Answers
Operable exterior thermal shutters

Hi,

We are building a duplex in Yellowknife, Canada - climate zone 8 (design temp minus 45 - same as Fairbanks).

Our winters are long and dark so some sort of (external) insulated window shutter is a huge energy saving opportunity. Our walls are going to R50, while triple pane windows get about R4.

I'm thinking of using 2-3 inches of Roxul board sandwiched between wood. That could give up to R12.

Asked By Andrew Robinson | Jun 10 14
3 Answers
Irregular rafter spacing

My 1907 house has 2" x 4" rafters on 34" centers. After stripping to roof to the original 1 x 4 skip sheathing, I am planning to add 6" of polyiso foam and then a layer of plywood sheathing. The scrap rate is high if I have to cut every sheet to 48 x 70". Is there a precedent for using tongue and groove roof sheathing (assuming I can find it locally) without the seams landing on the rafters in this sort of application?

Asked By Keith Richtman | Jul 29 14
4 Answers
Long room minisplit installation location?

11' X 30' room. Fujitsu 9rls2h. The specifications shows the flow pattern is long and skinny. Would it be best to install at the middle of the long wall or install at the end on a short wall? There will be ceiling fans at the midpoint and at the point farthest from the minisplit if on a short wall.

Asked By Shawn Shumaker | Jul 28 14
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