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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
2 Answers

Insulating detached garage attic in central Florida

I'm about to start construction of a 30' x 30' concrete block detached garage in central Florida. I'm using attic trusses and plan to use a white raised seam steel roof. I was not planning in insulate the block walls. What is the best way to insulate the roof? I want to keep it a cool as reasonably possible - I might add a window or portable AC, if I have to, but will not run it often. Depending on the final use of the attic, I might even try to condition that space. I'm concerned about moisture buildup inside - wet cars could bring a lot of water in.

In Energy efficiency and durability | Asked By Kelly Lear | Oct 3 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
4 Answers

1.5" of rigid insulation over stucco; Polyiso or EPS?

I have a stucco house in high desert New Mexico (zone 5B). The stucco is in bad shape after having been terribly abused by the previous owners, so I'm taking the opportunity to have the whole house wrapped in continuous rigid insulation as part of the re-stucco project. The boards would be applied over the existing deteriorating stucco, fastened through it and the sheathing and to the studs, and then a new 1/2" two-coat cementitious stucco cladding will be attached over it.

In Energy efficiency and durability | Asked By Nathaniel G | Oct 2 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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