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7 Answers

Air Sealing from the outside

Looking for some input. We are starting a project soon in Cambridge, MA. The house is a large structure built in 1869. Air sealing the envelope is a part of the program. We are stripping the two (2) layers of existing siding to expose the sheathing. We are not removing the existing decorative trim (cornice, large corner boards, window trim, etc) so there is not an opportunity to add much rigid insulation. We are presently discussing the approach to air sealing the sheathing. The architect suggested fanfold insulation with tape.

In Energy efficiency and durability | Asked By Bruce Friedman | Jun 1 12
20 Answers

Do I need another air barrier?

I've extended my rafters with luan gussets and 2x4s behind a future knee wall in my raised heel, attic trussed house. Zone 6. I've also built 1 inch vent chutes out of 1inch tuff r polyiso. Now I can fit two 5.5 inch roxul batts in the rafters, under the poly ISO chutes. Question. Do I need an air barrier under the roxul? If so, does it also have to be a fire rated? If not fire barrier rated, what are my options? I'd like to avoid sheetrock and use wood up in this part of the house. The ceiling below is 1/2 blueboard and plaster.

In General questions | Asked By stephen edge | Jul 30 12
17 Answers

Geothermal vs. air-source heat pump

I am building a tight insulated home in zone 6 and deciding wether to choose between ground water heat pump and air heat pump. After the 30% tax incentive there is not much increse in cost for the geo system. I am being told differnet stories in regard to system performance and longevity of equipment ( depending on what side of the fence your on). I am hoping to be in this house for the duration and willl be the last home I live in until my kids have to make the choice of where to send me. Dana

In Energy efficiency and durability | Asked By Dana St.Ours | Jun 2 12
4 Answers

GSHP Vs whole-home dehumidifier


I am looking at retrofitting my home with a GSHP (please see the below thread for details):


I am also planning to have an HRV and a whole home dehumidifier (Lennox 65-pint) installed as part of the new setup. My question is:

In Energy efficiency and durability | Asked By Venkat Y | Jul 23 12
6 Answers

Insulating recessed lights where there is no attic

I have an interesting problem. We have seventeen, 6" recessed lights in a ceiling that has no attic above it. We conducted an energy audit (we're putting in a 9 kw solar system and a host of other related changes) and found these to be a serious source of energy loss. The area where these are located is a single story, family room that just has the heat sucked out of it in the winter. These recessed lights are like chimneys.
While I am replacing most of our recessed lights with LED's, this one area I haven't touched as I need to insulate first

In Energy efficiency and durability | Asked By Alex HIllman | Jul 29 12
1 Answer

High solar gain windows in NJ?

I'm building a super-insulated house, 12" cellulose filled double-wall in South Jersey, R60 roof. I think the HDD are about 5000 and the CDD are about 1000. Should I be using high solar gain windows? Would they be cost effective?

In Green building techniques | Asked By Michael Arnold | Jul 29 12
4 Answers

Construction-detail Drawing Library

Would love to see drawings pertaining to double-stud walls or links to other resources providing these details. Any plans to create a library section dedicated to this subject?

In Green building techniques | Asked By ken dupuis | Jul 27 12
5 Answers

Earth tube for make-up air

I am planing on building a very tight house. Before I ever heard of "earth tubes" I was planing on providing make-up air. About 90 feet from the home I am going to build an out building. On this outbuilding on an exterior wall i was going to build a box that would hold a furnace filter from which I was planning on using 6" s&d pipe to run down 8' into the ground & then over to the house from where it would come up into a chimney chase & ultimately exit at the top of the conditioned attic space.

In Mechanicals | Asked By Eric Mikkelsen | Jul 28 12
3 Answers

Wet Spray Cellulose Dry Time

I'm building a house in Maine, we recently did a wet spray cellulose installation in the wall cavities, its a 2x6 wall with zip sheathing and 2 inches of poly iso on the exterior. We installed about 2 weeks ago and the cellulose is still very damp. I was told to drywall to prevent the cellulose from absorbing more moisture. I'm concerned about possible mold in the damp dark wall cavities. Any thoughts?

In Green building techniques | Asked By Mark Hinkley | Jul 26 12
1 Answer

Insulation refit and balancing the insulation.

House located in zone 2A, off the ground ~ 2 feet (1800 sq ft). The house has a sloped metal roof with 2 x 6 rafters on 24 inch centers and 2 x 4 stud walls on 16 inch centers. Currently there is no insulation in the walls or floor and 5 1/2 inches of fiberglass on the attic floor.

Attic Unvented (~R30) 5 1/2 inch fiberglass batt with 2 inches of rigid poly iso foam.
Walls (~R20) 3 1/2 inch fiberglass batt with 1 1/2 inches of rigid poly iso foam.
Floor (~(R13) 2 inches of closed cell foam.
Windows triple pane low e argon gas filled.

In Plans Review | Asked By David McMillan | Jul 28 12
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