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1 Answer

Capillary break over footing vs. vapor barrier under footing

Many building science resources recommend installing a capillary break over the footing (between the footing and foundation wall). Is there a reason this is preferable to installing a vapor barrier (i.e. 6 mil polyethylene) under the footing, up the inside face of the footing, and overlapping with the under-slab vapor barrier?

I'm assuming the foundation wall waterproofing extends all the way down the exterior face of the footing. I'm in Cincinnati, OH, and my question applies to finished basements, unfinished basements, and conditioned crawlspaces.

In Green building techniques | Asked By Eric Stear | Jul 31 14
8 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 [Editor's note: I think David means "rafters"], with the foil facing down between the knee walls. I did plan on filling all voids and foil taping the joints. Then 1/2" sheetrock over the foam. Just want to make sure this isn't considered a double vapor barrier, and if this would be considered good construction.

In Energy efficiency and durability | Asked By david chinn | Jul 27 14
1 Answer

Continuous rigid foam at the Jersey shore

Hello everybody.

I am currently designing a new single family vacation home in southern New Jersey on the beach. The project is going for LEED for Homes and Energy Star certifications. My main wall section from inside-out calls for 1/2" gypsum, 2x6 stud wall w/ batt insulation, 1/2 plywood, 1-1/2" rigid foam, WRB, 1x4 furring/air space, fiber cement siding. Air sealing details are similar to those offered in the GBA detail library. As a summer vacation home the main usage would be during the cooling season.

In Green building techniques | Asked By kevin field | Jul 30 14
2 Answers

Making a "summer cottage" livable in winter

We currently stay in a cottage 3 hours north of Toronto, Canada. The main level of the cottage has standard 2x6 insulated walls. I don't know what the roof insulation is like, but I will find out.
This cottage has so far only been used in the summer, but we plan to stay in it over the winter and want to do some permanent and/or temporary fixes to stay through the harsh Ontario winter in this cottage.
My biggest concerns are:
- only electric baseboard heat available right now, with very high electricity cost here

In Energy efficiency and durability | Asked By Hermann Thoene | Jul 30 14
10 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.

In Green building techniques | Asked By Troy Stevenson | May 7 13
0 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.

In Green products and materials | Asked By Mary Elzey | Jul 30 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

In Plans Review | 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?

In GBA Pro help | Asked By Michael Roland | Jul 25 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?

In Green building techniques | 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.

In Mechanicals | Asked By Shawn Shumaker | Jul 28 14
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