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3 Answers

Footing insulation

I am building an energy efficient house on a slab with 6 inch of EPS insulating panel under the a 5 inch slab. My architect is asking to add a 3 X 3 footing (on compacted soil) under the slab where the posts that hold the stairway to the second floor is meeting the ground floor and a second one at the bottom of the stair.

How do we go about insulating these footing to at least the same level as the rest of the slab do we just put the same 6 inch insulation under these footing as well as their rim?

In GBA Pro help | Asked By Pierre Gingras | Oct 5 14
12 Answers

Is external polyiso worth the cost?

First, let me say, that this community is fantastic. It is good to see so many people invloved and really dedicated to making building more efficient, and thus, playing a part in saving our planet and environment. I am always pleasantly surprised at how helpful everyone is, most of all, you Advisors. Thanks for the time and effort.

In Green building techniques | Asked By Kurt Samson | May 19 10
3 Answers

Does insulating the slab in climates where cooling dominates over heating make sense?

Foot note from Martin's http://www.greenbuildingadvisor.com/blogs/dept/musings/wolfgang-feist-de... article- 1. After I published last week's blog, I had a discussion on Twitter about this issue with Steven Toomey. Along with Anne Decker, Toomey has built a Passivhaus in Bolton, Connecticut that they call the Hayfield House. Toomey kindly supplied energy budget information from two iterations of PHPP for his house in Bolton, which is a two-story house built on a raft foundation. The raft slab has an area of 1,248 square feet.

In Energy efficiency and durability | Asked By bruce john stracke | Oct 4 14
5 Answers

Out-sulation vs Double Stud Walls

I was reading some old GBA discussions about double-stud wall designs and the added difficulty of keeping the sheathing dry (relative to wall designs that place appropriate amounts of insulation over the sheathing). This prompts me to wonder why the double-stud approach has its adherents when an out-sulation approach can be used to achieve the similar R-values and protect against thermal bridging while dispensing with the uncertainty regarding moisture. Besides being of general interest to me, I am hoping the responses will help me decide the 'best' way to proceed for a future project.

In Energy efficiency and durability | Asked By Rob Shuman | Sep 16 14
18 Answers

Windows for my Pretty Good House

Hi all

Another question for the experts here at GBA--this time about what windows I should install in my Pretty Good House (PGA). I've written here before about this house and you can likely find the threads of previous questions. Basically, we're building a single level, 1700 sf house in Hood River, OR and we're trying to meet PGA and passive solar "standards". Currently, we're trying to decide what windows to put in this house, and the candidates are:

Marvin Integrity
Milgard Ultra
Intus Arcarde or Eforte

In Green products and materials | Asked By Matt Mesa | Sep 29 14
3 Answers

Vapor barriers & mold

I live in a rural area (95415) without attic , only some walls with R13 insulation.

I am considering NSF certified elastomeric paint to cover shingles for the purpose of collecting rainwater for potable uses. It serves to cover toxic shingles, acts as a cool roof as well as a vapor barrier.

I am also planning on 2-3 coats of latex paint for the interior walls and ceilings of the kitchen and bathroom. This should also act as a vapor barrier.

I'm wondering if any building science folks might comment on the potential for mold potential between 2 vapor barriers.

In Green products and materials | Asked By Laura Diamondstone | Oct 2 14
3 Answers

Expanded polystyrene and water-resistive barriers

I cannot tell whether the ICC-ES has approved expanded polystyrene for use as a water resistive barrier when installed over wood. I can only find that EPS has been approved for stucco. Secondly, I am having difficulty locating the testing procedures described by Mr. Holladay that must be followed when installing insulated vinyl siding, AC71. I note in his article he states flanged windows and Z-flashing must be used. And certain sealing requirements must be met. Any other installation criteria? And if so, are they printed anywhere?

Thank you.

In Building Code Questions | Asked By Daniel Nealon | Oct 2 14
1 Answer

How to protect a shallow monolithic footer during winter construction, zone 5

We have a Passive House design, which includes a shallow and 1'4'' wide mono footer. 4'' floating slab has 12'' deep thickened edges. 12'' under the slab are insulated. There are 4'' of EPS on all 3 sides of the footer. (see detail/picture).

In PassivHaus | Asked By Lucyna de Barbaro | Oct 1 14
3 Answers

Manual D spreadsheet examples?

Hi, I'm looking for any completed examples of the Manual D spreadsheet which is given out free from ACCA: http://www.acca.org/standards/acca-speed-sheets/

Thanks to this site for educating me on the importance of Manual J and D calculations. I know there's software for this but a) I'm cheap, and b) I'm a nerd and like to get into the details.

My hard copy of the manual is in the mail and while I wait I'd like to figure out the sheet as much as possible.

In Mechanicals | Asked By Jonathan Dalton | Oct 1 14
12 Answers

Breaking thermal bridge between concrete porch and brick wall?

I have a concrete-floor porch that replaced an original wood-floor porch. It butts up right against the double-brick wall of the house (built in 1905). The house is uninsulated, so I am insulating the brick wall with rigid foam board. While I'm at it, I am thinking it is a good idea to saw-cut a 1" or 2" slot of the concrete floor right along the base of the brick wall (in other words, the floor-wall joint) to get rid of the thermal bridge that might exist, then to backfill the slot with rigid foam. Does this sound like it would make a significant difference to heat conductivity?

In Green building techniques | Asked By Paul Gorcey | Sep 26 14
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