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4 Answers

Exterior insulation while re-siding with an interior poly VB

I've been reading a lot of articles and questions/answers from this site and many others in preparation for a re-siding project. I am located in South-East New Brunswick, Canada, our climate zones run different than the US, but I believe it would be similar to Bangor ME which is zone 6A.

To the best of my knowledge the wall construction (1977 build) is, from the outside in, vinyl siding, felt paper wrap, board sheathing, 2x4 walls, fiberglass batt insulation, 6mil poly VB, 1/2" drywall.

In General questions | Asked By Scott Smith | Jan 9 13
7 Answers

Adding rigid foam to living space side of wall


I have a project in the Boston area where I would like to add and inch or so of rigid insulation to add some R value and knock down the thermal transfer and air-seal. The problem I'm saddled with is the wall that I need to work on is the gable end of the house and I'd have to extend the roof and move the electric meters and weather head if I thicken up the exterior wall by adding the foam and rain screen, and also add the new siding.

In Energy efficiency and durability | Asked By Steve Greenberg | Jan 15 13
4 Answers


I hope this is not a dumb question...but what exactly is the V-factor in the 2009 IECC. I shows up several times in Section 4 for example, Sec 402.1 .3 V-Factor Alternative. I think it is the same as the U-factor....but why are they referring to it as V-Factor.


In Building Code Questions | Asked By Bruce Friedman | Jan 15 13
4 Answers

New bath fan - condensation drip

Hi, I'm a long time troller but a first time poster.

We are in CZ 3 - San Francisco Bay Area. Mild year-round, dry summers, wet winters.

As pat of a larger renovation, we installed a Panasonic WhisperGreen fan/light combo in the bathroom. The homeowner later complained that when they take long showers, or sequential showers, they get a slow drip out of the bath fan. A single 5-10 minute shower poses no problem. I have not observed the actual dripping, but did see the drip stain.

In Energy efficiency and durability | Asked By John Kidda | Jan 16 13
4 Answers

Graywater filtration system

I have a customer requesting the installation of a grey water filtration/recycling system. The customer lives in the DC area and has explained that these systems are common and considered "green" in application in the urban DC area. The home I will be building for the customer is in the rural mountains of West Virginia. There is no shortage of water up here we have received close to 35" this year to date and average about 60" a year.

In Green products and materials | Asked By Joseph Garten | May 22 11
1 Answer

Insulating at Steel Beam

Good evening,

This question is for a new construction home, climate zone 4A, with north being to the right in the attached PDF. I was planning on using OC spray foam directly under the roof sheathing and in the walls, but I changed my mind during construction after reading accounts of problems with the foam installations, particularly during the winter. I now am now using dense packed cellulose in the walls and using loose fill cellulose on the ceilings.

In Plans Review | Asked By David Baca | Jan 15 13
4 Answers

Degree-day data sites?

What are peoples' preferred internet sites for obtaining
heating/cooling degree-day stats? I'm looking for a
place I can get any of day-by-day, monthly/yearly tables,
etc for fairly localized points. I will need to do this
programmatically, i.e. sites that depend on javascript or
other browser fluff won't do, and the data needs to be
available in a straightforward fashion without having to
install any special "apps" or plugins. Wunderground.com
allows looking up historical data for various airport-based
stations and isn't a bad start, but I don't necessarily want

In General questions | Asked By Hobbit _ | Jan 15 13
13 Answers

Spray foam hybrid flash and batt help! wet wall cavity

We have new construction and have dry wall up and painted. Have spray foam 2" on exterior wall and flash and batt in wall cavity. Had a cold snap and with humidity in house the vapor went through wall on north and east side of house, hit the spray foam and condensed. We have heat on 62 and have 2 contractor size dehumidifiers running. The humidity level now is 50 , basement is 55. Has been a whole week. How long to dry. It is maine, and rainy out for next 3 days so feel that high humidity outside may help to drive vapor back inside.

In General questions | Asked By James Bernier | Jan 12 13
7 Answers


I am an energy consultant working with homeowners of existing homes. Could use a little input on a recent question. Customer has a second home, upstate NY, ZONE 5, and resides only weekends. Asks what should I set back my t-stadt to during the 5 days a week we are not here? 1998 home, oil boiler, 3 zones, indirect hot water heater. Typical conventional (ranch) construction. I have come to believe too much setback short-term can be both an energy and comfort penealty in an average to poor enclosure home.

In Energy efficiency and durability | Asked By mike Eastern NY | Jan 13 13
4 Answers

Double stud-wall construction: inner or outer load-bearing wall?

I have been investigating a lot of framing options to achieve a relatively inexpensive, high r-value wall and have decided on building a double stud-wall made of 2-2x4 walls with a 7.25" space in between (to achieve what I want for an r-value). I have come across differing methods of distributing the load from above; inner versus outer load bearing wall, or a combination of the two (inner for the second floor joists and outer for the roof trusses). And then there is Larsen Truss construction.

In Green building techniques | Asked By Matthew Michaud | Jan 14 13
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