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15 Answers

American-made Passivhaus-certified windows

Hello All,

In PassivHaus | Asked By Bob Holloway | Sep 23 14
2 Answers

How do you calculate the net free area of an attic vent?

How does a manufacturer of vents determine the Net Free Vent Area of a vent that they put on the market?

In Building Code Questions | Asked By George Sherry | Sep 27 14
11 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
4 Answers

Improving R-value of 2x4 wall in renovation with interior foam board

Hi gang,

Doing a renovation in MA, USA, and I need a little help... There's a 2x4 wall that needs insulating, and I'm not redoing the exterior of the building. It would be easiest for me to get the wall dense-packed with cellulose, then go over the whole thing with 2" foil faced foam... but I have a couple questions...

In Energy efficiency and durability | Asked By Eric Nash | Sep 23 14
40 Answers

I am using Roxul insulation for ceiling and walls in a post-and-beam barn home

I plan to use this insulation in a 2x8 ceiling and 2x6 stud walls. Roof is sheathed in OSB, with a Titanium underlayment with standing seam on top. Walls have OSB and Tyvek house wrap. My question is can I use a poly vinyl vapor barrier on the interior after installing the insulation and then cover with 1x6 tongue and groove pine board. I have seen conflicting information on this. We are in Kansas which I think is Zone 6. This is a full post and beam barn structure. It has a gambrel portion with a loft. Loft has 12' high ceilings. Lean to portion has 9' high ceilings.

In GBA Pro help | Asked By David Hauber | Sep 25 14
1 Answer

Lawyers, Engineers and Builders Oh MY!

A place to debate or kill some time

In General questions | Asked By aj builder, Upstate NY Zone 6a | Sep 27 14
28 Answers

Options for high R-value above-grade walls (R-80)?

To make a long story short, my above grade exterior walls need to be at an R value of 80. This is to meet Passive House standards for a new residential house in a very demanding climate.

I am currently planning on using SIP's of some sort. But even the best of those only get me up to around R-50 though. Any thoughts on ways to get to R-80 while still being cost effective and keeping the size of the wall to a minimum?

I have found a number of options myself, but was curious if anyone else had thoughts or suggestions to meet such a high R value for a wall.

In Green building techniques | Asked By Tom Schmidt | Sep 19 14
6 Answers

Flash and Batt in Reverse - Modular

Working on a modular residential project in CZ 6. In modular construction though, the batt is installed on the exterior facing edge of sheathing and closed-cell spray foam on the interior facing edge of the gypsum (serving as vapor barrier). Would this flash and batt insulation in reverse cause any problems with moisture transfer?

Also, if we could, does it make sense to add an inch of Poly iso or Roxul on the outside of the sheathing as a thermal break to the outside to increase R value and add a thermal break?

In Green building techniques | Asked By Chris Parker | Sep 26 14
3 Answers

Old house with no sheathing/vapor barrier

I have an old house with no sheathing or vapor barrier, just clad siding on top of studs. I have the interior gutted and I am set to add batt insulation and new drywall back as it was originally. Should I add felt on top of the insulation and under sheetrock as a vapor barrier...still allowing the wall assembly to dry to the outside? or will it condesate on felt in summer and rot studs/etc.

ps I am in SC...really hot/humid.

In Energy efficiency and durability | Asked By charles elrod | Sep 25 14
10 Answers

Best place to buy rigid foam insulation?

In general, where have you found the best price on XPS and Polyiso? Lumber yard? Big box stores? Other? We are in the design stage of a new custom home project and I want to analyze price/performance as we are creating the plans. In the past I have relied on my stucco sub to provide it in his bid, but we will install on this project. Thanks for your input!

In General questions | Asked By Bill Costain | Oct 11 11
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