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1 Answer

Heated line in attic crawl space

My house has some unfinished crawl spaces where the heater pipe line runs trough. In the winter i get ice dams due to the loss of heat. Should I spray insulation over the expose copper lines to keep this spaces cold or should i spray the roof rafters? I tried insulated sleeves but don't seen to work.

Thank you for your responses.

In Energy efficiency and durability | Asked By nestor lopez | Mar 15 12
3 Answers

Flash and batt and Vapor barrier / retarder

Hello GBA,

I have a builder who is building in Zone 5 / 6 line (NH), 2 x 6 w/ a "flash and batt" wall insulation strategy. I haven't been a fan of the F&B strategy in the past, and not sure I will become one w/ this job either.

2" CC, R6.5?? sprayed 1st, w/ an R15 high density f'glass batt going in 2nd. The builders question is: What, if any, vapor barrier or retarder s/b used?

In Energy efficiency and durability | Asked By Kevin Hanlon | Mar 14 12
5 Answers

Ventilating Stairways in Multifamily Buildings on the Cape

I am renovating a five building development in Orleans, MA that includes a new envelope (windows, added insulation on the exterior and new siding). I am also planning to add fresh air to the small (2 stories) stairwells in each building. Should I be concerned about humidity so much that I add a cooling system as part of the ventilation? There will be continuously running bath fans in each unit and existing through wall AC units. I don't want to overdesign for a few days a year that I might generate condensation because I am not cooling the make-up air.

Thanks for any help.

In Mechanicals | Asked By julie klump | Mar 14 12
34 Answers

Retaining heat at a garage door; part 2.a.07x

Fairbanks, AK, zone 8. This is an iteration of a design I asked about last year; different foundation system, somewhat different ramp. I looked for that thread to see exactly what was said, but could not find it, so I apologize if old ground is being dug up again.

I am still struggling with getting some kind of heat retention at a garage door, a desire that may be nearly pointless given that garage doors notoriously leak. (That said, I was sitting inside my neighbor's the other day at 20 below, and could not detect any leakage by hand, fwiw. 2 story, non-super-tight house.)

In General questions | Asked By John Klingel | Jan 24 12
1 Answer

Exterior Foam Thickness - Atlantic Canada


It seems that the concept of an interior moisture venting is quite new and some experienced builders brush off the idea.

I am looking at building a house I will personally live in, and I intend to live in comfort, on reasonable energy efficiency, and of course durability of structure.

The design I am currently looking at would consist of; from outside to inside:

-Properly screened air gap
- 2 x Layers of 2" Polyiso with joints sealed and staggered
- Tyvec Drainwrap (adhesive membrane flashing)
- 1/2" Plywood
-5.5" wet blown cellulose in 2 x 6 framing 24" c/c

In Energy efficiency and durability | Asked By Jean-Philippe Levesque | Mar 14 12
16 Answers

Double Stud Wall section

Although there is a lot of discussion and recommendations for double stud walls (R40) filled with dense packed cellulose walls on GBA, I could find no diagrams of a recommended wall assembly in your strategies and details section.

We are in the preliminary design phase for a two story house in Upstate NY (2,200 sq ft - first floor 1,500 sq ft), second floor 700 sq.ft.) (Zone 5a) built on an insulated (R20) floating slab and plan to have a vented roof (R60) with raised heel trusses over the two story portion of the house. I would like a sloped roof over the single story living area.

In GBA Pro help | Asked By Elizabeth Kormos | Mar 12 12
3 Answers

Is high solar gain glazing worth the extra money in mid-Michigan?

We are currently building a home in midwest MI. It has a mono-slope/shed style roof with the tall wall (14', total of 66' long) facing approximately 15 degrees east of true south. We will have concrete floors throughout the main level (and basement), infloor heat. Limited, small windows on the west/east/north side. We have tree shelter on the west and north sides of the home.

In Green building techniques | Asked By Cara Masselink | Mar 13 12
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 12 12
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