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1 Answer

Insulating bottom of radiant floor

I have a radiant floor that was installed under my kitchen floor using the aluminium heat transfer plates. Below the kitchen is a semi finished, semi conditioned basement. I would like to insulate the floor to allow as much of the heat from the pex tubing to translate to the floor (rather than helping heat the basement). Is a radiant barrier (foil) with an airspace beneficial? does the insulation need to be installed airtight? Is fiberglass a good choice in this application? Any insight is appreciated!

In Energy efficiency and durability | Asked By Pete Marthaler - Zone 7 | Apr 18 14
2 Answers

Does anyone here have direct experience with AirKrete Insulation?

In an answer to a recent question I had, Martin Holladay indicated that he has concerns about AirKrete shrinking and crumbling. According to the website and company representatives, AirKrete has 0% shrinkage and the formulation has been changed to alleviate the friability concerns.

I'm interested to know if anyone here has used AirKrete and, if so, what your experiences are with it.

Thanks in advance!

In Green products and materials | Asked By Stacey Owens | Apr 15 14
3 Answers

Polystyrene under a footing or load-bearing wall?

Hey guys, what are your experiences with putting a 100 psi polystyrene under a footing to help eliminate as much thermal bridging as possible? This is for a residential setting. It would be in the center of the house the load of the first and second floor and possibly the roof would be on it.
Can anyone recommend a engineer that may have experience in this?
Thanks.

In General questions | Asked By Kirk Nygren | Apr 16 14
11 Answers

Is a fully dedicated duct system for HRV truly the best option?

So, I’ve been researching the proverbial pee-pee out of this question: dedicated ductwork for my HRV or simplified installation? Here are the pertinents:
• Climate Zone 6
• 2700 sq. ft. story-and-a-half house, along with a 2000 sq. ft. unfinished basement
• 4 Bdrm, 3 ½ bath house
• Double stud walls, spray foamed exterior sheathing and cathedral ceiling, very “tight” and efficient house planned.
• Geothermal ground source heat pump, with gas furnace back-up (Xcel Energy “dual fuel” program allowing electricity to be purchased at 40% rate for geo.)

In Mechanicals | Asked By Kent Jeffery | Apr 15 14
1 Answer

Move the interior 2x24 vertical EPS to the outside of foundation?

For anyone who naturally performs THERM calculations in their head, the answer would be intuitively obvious, but to know for sure I'd have to stop and learn THERM (which wouldn't be a bad idea).

Before I build this, would it be better to place to layers of vertical 2" EPS on the outside, maybe 32" and 16" deep, to reduce what looks like an excessive thermal bridge right at the top of the foundation?
Cross section:

In Plans Review | Asked By Chuck Jensen | Apr 16 14
9 Answers

Looking for low cost and novel way to form concrete footers

I am using ICFs to form a foundation stemwall and am pondering different ways to form a 16" x 8" footer that doesn't require a ship load of 2 x 8 or 2 x 10. I can't form it using the trench walls because county code requires 38" w x 12" deep compacted structural fill below the footer for my soil type. My thought is to use ripped plywood with some kind of wire or snap tie and 2x4 strongback with some fill holding the bottom in. If using plywood, what is a good sealer to use for saving and further ripping the plywood to use as furring strips for siding? Any cool cheap ways to form footers?

In General questions | Asked By Chuck Jensen | Apr 15 14
3 Answers

To condition (the attic) or not to condition, that is the question!

After reading and reading and reading (including lots of GBA articles), I thought that I had this figured out. Our plan was to have a non-conditioned attic space, with continuous soffit ventilation along with ridge vents. After further reading, especially Dr. Joe's Top 10 List of Dumb Things to do in the South, I am confused. Please share whether you would vent an attic or not with the following considerations in mind:

- located in western North Carolina, zone 4, mixed humid
- one level, slab on grade home, approximately 2100 sq. ft.

In Green building techniques | Asked By Stacey Owens | Apr 15 14
1 Answer

Windows and Exterior Rigid Foam

I am installing new windows and cement board siding. We are adding an inch of foam board to the exterior. I know the siding can be nailed through the foam board into the sheathing by extending the length of the fastener, but can the same be said about nailing the window (flange) through the foam board? I realize that I have either that option or the option of building out my frame by an inch with OSB or ply so that I get a solid nailing surface. Is there a preference?

In Green building techniques | Asked By Matt Cibula | Apr 16 14
1 Answer

EPS & SIPs

Since a SIP is basically like an I-beam type of setup, it relies heavily on the EPS foam core for its strength. The downside is that EPS begins to melt around 165F - 180F. Once the foam fails, the structure fails/collapses.

Has anyone observed or read about a SIP roof or SIP wall home being involved in a fire? If so, what was the outcome?

What's the hottest temperature that a SIP roof can get? I assume in the desert southwest a SIP with a metal roof on top can see some high temps. Is it hot enough to melt the EPS core?

In Green products and materials | Asked By Peter L | Apr 16 14
6 Answers

PassivHaus barndominium in Minnesota

Hello everybody. First post -- just signed up. Great site. I live 30 minutes north of the Twin Cities and I'm looking at building a passiv type haus. I've found the land I'm building on (10 acres) and have somewhat of a plan for the building.

My wife and I want to build a barndominium. Looking at 50x70 total with 30x50 two stories and 40x50 shop. I have a general idea of how I want to build but alas I am newb and was hoping for some insight with the pros on this site.

Thanks again and any advice would be greatly appreciated.

In PassivHaus | Asked By Ryan Picha | Apr 1 14
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