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1 Answer

Gaps in exterior foam - how to insulate underside of roof?

We're finally getting ready to insulate our roof, & after many hours of research have been unable to come to a consensus on what type of insulation to use. We are in climate zone 3 (central AL). This is an unvented cathedral ceiling, 12/12 pitch, & once finished will have sheetrock installed on the underside of the rafters (no can lights, etc). Currently the roof consists of:

2"x10" rafters on 24" centers,
1/2" OSB,
30lb roofing felt, with Ice & Water Shield on the ridge & in valleys,
1.5" foil-faced polyiso,

In GBA Pro help | Asked By Jessica Akau | Nov 23 12
1 Answer

Roof venting

We are building a 3/12 shed roof with parallel trusses North of Ottawa (zone 6-7). The roof is sloping to the South. We're wondering about potential for venting problems during winter with North and NE winds, as we think the wind catching the North wall will disrupt the normal venting of the roof. The site is fairly protected but these winds will blow on and off throughout the winter.

In General questions | Asked By jessie pratt | Nov 23 12
1 Answer

How to insulate unvented attic with foil faced rigid foam in 6 inch bays?

Im currently remodeling my house in southern california. Im interested in building an unvented attic since all my HVAC equipment and ductwork are in the attic. In addition, we've had rats and mice nesting in the fiberglass insulation before we tore it all out. This is a single story, 3200 sqft ranch house that will have quite a few vaulted ceilings. With that in mind, what is the best way to use foil faced rigid insulation to create an unvented attic?

Option 1: 5 inches of JM AP foil-faced polyiso screwed directly to the undersides of the rafters and foamed and taped to air seal

In Green building techniques | Asked By andrew shu | Nov 22 12
1 Answer

Attic trusses - insulation question

Followup for clarification on at ICF home with attic trusses. I do plan to insulate the attic truss floor for two reason. !st is for noise reduction and the other is that this area will only ocassionally be occupied and will have reduced temps most of the time. Can I get away with spry foaming the roof trusses soffit to soffit with 2" and then putting in batt insulation to fill the cavity. I do plan to very soon finish this area so do I also need to insulated the side walls of the room if the rafters are already filled with insulation.


In General questions | Asked By Jim McKay | Nov 22 12
0 Answers

Roofer in Central Vermont needed

I have asked questions in the past about "ag style" metal roofing with ice and snow shield installed under it with an air space for ventilation for a school and gotten good feedback. Now I would like to go the next step to finding a roofer who could install such a roof in the Rutland, VT area. All the roofers I have spoken to immediately say... standing seam only- no discussion. Are there roofers in this area of the world with more open minds? Anyone to suggest? It is a 6,000 sqft building.

In GBA Pro help | Asked By Adrienne Raymond | Nov 21 12
8 Answers

Is it more energy efficient to insulate roof slopes or the floor of an attic?

Ignoring all other things, from a pure energy efficiency perspective, is it more energy efficient to insulate the slopes or the floor of an attic? Assume in both cases a vented attic (even if insulating slopes, there is fiberglass down below that needs to be vented. If insulating slopes, would you also endeavor to plug up holes in the floor, or is that unnecessary once attic is brought within house envelope?

In Energy efficiency and durability | Asked By Moya Mim | Nov 20 12
8 Answers

Should I exhaust from the bedrooms or the baths?

For a 2000 sq foot, 2 story house, with superinsulated 12 inch double stud walls in South Jersey, how should I best provide ventilation?

The design offers multiple choices. I can easily add a HRV with ducts drawing from the bedrooms or the baths or the kitchen or any combination of those. I have seen discussion on the GBA about the "smells like teen spirit" effect and I appreciate that lyric as I have two teen boys in those upstairs bedrooms.

In Mechanicals | Asked By Michael Arnold | Nov 20 12
3 Answers

Should I use two layers of 1 inch or one layer of 2 inch rigid foam board on the exterior?

Should I use two layers of 1 inch or one layer of 2 inch closed cell rigid foam board on the exterior? Locally we have available foil-faced on both sides. My understanding is to have only the exterior side foil faced. If using two layers of 1 inch, then should the board against the stud be unfaced?

I've read the articles on rigid board insulation on the exterior and concerns of condensation. I live in a warmer part of zone 5B at 3,400 ft. elevation.

In Green building techniques | Asked By Brad Dorken | Nov 20 12
2 Answers

Capillary break over footing

We are unfortunately under some time constraints and are looking into damp proofing our foundation footing before the foundation wall is poured. How long should we wait before applying a damp proofing product? The product should also be able to dry quickly and at temperatures around 46 degrees Fahrenheit.
I should mention that the site is dry as a bone sand. Maybe we can go without a capillary break between the footing and foundation wall?

In General questions | Asked By jessie pratt | Nov 20 12
9 Answers

Venting a small hip roof with the hip peak touching the house

I have a small section of house with a small hip roof of approximately 128 sq.ft. in area. Based on my calculations I was planning to install 5 round 4" soffit vents (http://www.homedepot.ca/product/4-inch-white-circular-louver-resin/935118) and a single square roof vent (http://www.homedepot.ca/product/60-nfa-brown-roof-louver-high-impact-res...). From other reading I gathered that the outtake should not exceed intake, so should I install an additional soffit vent to keep the ratio approx. 50 / 50 ?

In GBA Pro help | Asked By Mike Tew | Nov 19 12
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