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3 Answers

Use of rigid polyisocynene on exterior wall system

I'm building a house in Wisconsin (zone 6) and plan to use an inner wall structure filled with dense-packed cellulose covered by 4 inches of rigid polyiso on the exterior, topped with battens for a rain screen. I believe polyiso on the exterior is endorsed by Joe Lstiburek, Martin Holliday here at GBA, and also the Journal of Light Construction. It would serve triple duty--thermal break, WRB, and drainage plane. But my architect does not agree, saying polyiso will prevent drying to the outside.

In Energy efficiency and durability | Asked By Bill Keenan | Mar 9 12
1 Answer

Crawl space questions

You answered a question on moisture in the crawl space for my sister's old house . Now I have two more questions.

1. Since her house is so large and they mainly only use certain rooms, is it possible to only air seal a section of it? And I know it must be for air movement that you put the plastic on the ground; could I put it closer to the floor joists?

2. When running the plastic in the crawl space - what do you use to join pieces together and how do you seal it around the concrete piers and other structures under the house?

In Energy efficiency and durability | Asked By William Wingett | Mar 13 12
7 Answers

Beautiful wood fireplace needs a heat exchanger or a propane insert to become energy efficient

I have a lovely wood burning fireplace and I can't decide whether to get a heat exchanger installed and keep the wood burning or get a propane fueled insert installed.

My house is built entirely of concrete block in 1955, It is about 1,100 sq feet located in SE CT. It has a very open floor plan and could possibly heat most of the place with the right modification.

I'm hoping to cut my oil bill, which is approaching 2k this mild winter. Propane tanks are the only other fuel alternative, but I'm concerned about running gas lines through the concrete and the safety of it.

In Energy efficiency and durability | Asked By Katherine Slufik | Mar 11 12
4 Answers

Location matters?

Hi, I'm a graduate student working on my thesis project called "Eco-Solo," which means that people living in a one-person household would consume more energy than other kinds of households.

My direction is to create cohousing in high-density urban areas so people can share energy and equipment. Instead of conserving energy I also try to apply passive techniques into apartments in urban areas.

In PassivHaus | Asked By I-Ting Chung | Mar 12 12
4 Answers

Venting rafter bay with skylight

Building living space in attic - sloped cathedral ceiling to 8' high level, then flat
using Velux windows and fixed skylights in roof assembly.

How do I vent the rafter bay when the rafters are cross-blocked at the skylight framing?
E.g., rafters @ 16" oc - skylight rough opening 46 1/2 x 46 1/2".
"Rafters" are 16-inch I-beams.

Venting: soffits consist of 1x4 clear cedar spaced 3/8" apart. Installed perpendicular to house wall.
Black landscape cloth (perforated) continuously fixed underneath lookouts as bug-screen.

In GBA Pro help | Asked By Rainer Semsch | Mar 12 12
6 Answers

Basement Floor Underlayment foam or no foam

I am installing a floating cork floor on my basement slab and have decided to use a dimpled underlayment. One product instruction says to maintain a gap at the vertical edges, the other says to foam the edges.



I'm leaning towards the foam for the same reason I foamed around the XPS against the concrete walls - to avoid the conditioned interior air from contacting the concrete.

Foam or not to foam...?

thank you

In General questions | Asked By Frank O | Mar 11 12
1 Answer

Insulated Slab

I have a few questions about an insulated slab detail found in 'strategies and details" section (http://www.greenbuildingadvisor.com/green-basics/slab-foundations). What is the ideal substrate underneath the rigid insulation board and where, if necessary, should a vapor barrier be placed? In the past I have constructed in this order... slab, vapor barrier, 4" of gravel (passive radon vent integrated if EPA zone 1 or 2).

Thanks for the help!


In GBA Pro help | Asked By David Epley | Mar 12 12
4 Answers

Blown-in cellulose in a finished garage ceiling (conditioned space above)

Hi all,
Been putting this off til warmer weather and nows the time I push the button or not
Ok I have a 4 yr old 2 story colonial in NY (20 miles N of NYC) so the usual questions we see on the forum, why is the room above the garage so cold.
So Ive cut some holes and found the builder had put F/G Kraft paper batts in R30

In Energy efficiency and durability | Asked By Darren Finch | Mar 11 12
9 Answers

Avoiding thermal bridge under doors at slab on grade?

Due to extensive shallow ledge, I'm designing a slab on grade foundation for a seaside home in Massachusetts (Zone 5A). Because of gently sloping topography, neither a thickened slab edge nor a frost-protected shallow foundation seems possible, so I intend to use a frost wall with a slab separated thermally by rigid insulation.

In Green building techniques | Asked By John Rockwell | Mar 10 12
13 Answers

Is there a "direct vent" clothes dryer or kitchen hood?

It seems to me we focus on creating super tight envelopes and then cut holes in it to purposely blow out an enormous amount of air with clothers dryers and kitchen hoods. We either create negative pressure in the home or bring in unconditioned air with make up dampers. HRV's and ERV's now solve that issue with bath fans, but isn't there anything out there for dryers and hoods? My thought is there should be some kind of venting system like the direct vent on the back of a fireplace where the incoming air gets conditioned by the outgoing air.

In Green building techniques | Asked By Andrew Homoly | Oct 6 11
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