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35 Answers

Will mold grow between foam panels in the wall?

Hi, I am planning a new house in Wisconsin with 2" x 12" wood framing. The wall will be: drywall, 6" thick faced fiberglass batt, 3 foam panels 2" thick each, plywood sheating, house wrap, tar paper, corrugated stucco wrap, stucco. I am wondering if there is a problem with condensation between the foam panels causing mold. I am planning on making the drywall and plywood be air barriers. Also, instead of 2" x 12" wall studs, I am planning on two 2" x 4" studs with a 4" space between them for insulation.

In Energy efficiency and durability | Asked By Dennis Vogt | Oct 8 12
6 Answers

What would be the best low VOC product to seal cedar to prevent its natural VOC emissions?

My wife is very sensitive to VOC's. We have an expensive 3 year old oak bedroom dresser and two matching nightstands with a total of 20 drawers that have dovetailed joints and cedar sides and backs. The cedar in the drawers is causing my wife headaches, and we will have to sell the furniture at quite a financial sacrifice unless I can find a low VOC coating of some kind, primer, polyurethane, whatever, to seal the cedar well enough to prevent its natural emissions. Any ideas as to what would work would be very appreciated.

In Green products and materials | Asked By James Day | Oct 14 12
3 Answers

Top plate sealing? (ADA)

We plan on using Conservation Technology EPDM gaskets between the slab and (bottom) sill plate. And then some form of gaskets to create the airtight drywall approach (either the ones from conservation technolgy or Denarco).

What I am still a little unclear about is what if any seal is needed at the top plate(s)? The house will have a double 2x6 top plate. I have looked at a few different diagrams about ADA and weather sealing and for some reason I am still confused.

I found this diagram from an older post by John Brooks (hope you don't mind me using it):

In Energy efficiency and durability | Asked By Jack G. | Oct 17 12
5 Answers

Are there closed-cell spray foam products that have low global warming aspects on the market now?

Are there closed-cell spray foam products/manufacturers that have low global warming aspects on the market now that folks can recommend?

I just read the article "Avoiding the Global Warming Impact of Insulation" and was wondering if the closed-cell industry has offered up any alternatives.

In Green products and materials | Asked By Daniel Weaver | Sep 21 12
7 Answers

Comments on Wall Assembly

Hi there,
I've been reading a lot on this board and have been working my architect to design a well insulated, energy efficient house. I would like comments on the proposed wall assembly;

The house is ~3000 square feet. It will be heated with Geothermal either via forced air distribution or radiant in floor heat.

It is a two story house consisting of the following

5" stone masonry on the 1st floor and stucco over 4" concrete block on the 2nd floor
1" vented air space
2" closed cell spray foam
5/8 exterior grade plywood
2x6 wood studs 16" OC

In General questions | Asked By Howard Klein | Oct 15 12
13 Answers

Non foil faced polyiso

Building a new house in Southern California (climate zone 3). House is single story and about 5,000 sq. ft., so there is considerable wall square footage.

The walls will be:

1. airtight drywall (it probably won't be perfect, but hopefully pretty good)
2. cellulose
3. 2x6
4. plywood or OSB (depending if it is a shearwall)
5. possibly 1" polyiso (depends on the responses to this post)
6. Tyvek type material (still reading whether it's better on top of plywood or on top of foam insulation). If i use foil and tape all the seams - I may not need Tyvek???

In Energy efficiency and durability | Asked By Jack Garden | Oct 12 12
3 Answers

What to do when there's no foundation?

We did a major renovation over 10 years ago. As part of that reno we enclosed what used to be a porch. One forced hot water register was installed and the underside of the flooring was covered with insulation. The room is very cold. It is approximately 4 feet in the air supported on concrete filled tubes. Other than digging and pouring a foundation under this space is there anything else we can do.

In GBA Pro help | Asked By daiva Neihardt | Oct 14 12
2 Answers

Sealed Crawl Space Ventilation

I am in the process of conditioning my crawl space in southern Ontario. The ground is very sandy and the foundation in 100+ year old stone. I am planning on using 2 layers of 6 mil poly (10 mil if I can find it) to cover the ground and using a spray foam on the foundation walls and up into the joist spaces. The crawlspace is about 2-3 feet high and covers about 700 square feet.

In General questions | Asked By Graham Vickery | Oct 15 12
5 Answers

What are the negative aspects of using Tyvek on a double wall system instead of plywood sheathing?

I am detailing the exterior walls to be a double wall, its sequence as follows from interior to exterior: gypsum board on structural 2x6 with rockwool insulation, 1/2" plywood sheathing, continuous 10 mil vapor/air barrier, 11 7/8" TJI joist with dese packed cellulose insulation, 1/2" plywood sheathing, WRB membrane, 1x3 rainscreen furring strip and hardi-plank siding. I have read Thorsten Chlupp's wall detail that uses Tyvek thus eliminating the use of the 1/2" plywood and WRB membrane.

In Green building techniques | Asked By Karen Bala | Oct 11 12
3 Answers

Using grey water to wet geothermal loops?

I can't find any info as to if this has been done or if it is a terrible idea. it seems like it would not be too hard to use graywater to wet geothermal loops to help them work more efficiently. I'm assuming this is a bad idea since I can't find any info on it...thoughts?

In General questions | Asked By Eric Mikkelsen | Oct 13 12
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