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4 Answers

Unvented Roof, 3B, Foam-Free

Hi Martin,

First off, I have read a wealth of articles on the subject of unvented roofs, by yourself and Joseph Lstiburek. I started with your “How to Build A Cathedral Ceiling” article and read pretty much everything related to this from you and Lstiburek. The conclusion being that for an unvented roof you either install closed-cell spray foam between the rafters, or rigid foam above the sheathing at a thickness dictated by your climate zone to keep the sheathing warm enough.

In GBA Pro help | Asked By Joe G | Aug 26 15
9 Answers

Does an 850-square-foot house have to have return air ducts?

I live on a slab one story home. I currently have an old forced air gas furnace that I would like to get replaced as well as install central air conditioning. I had a local contractor come out and quote a complete system and was told I would need all new ducts because I didn't have a return air system. The furnace currently is in a central closet with a large air grate on the side letting air back to the furnace. It is right in the middle of the house and I usually leave all doors to all bedrooms open. He quoted me $12000 for the whole job.

In General questions | Asked By Brett Obraza | Aug 27 15
44 Answers

Re-roof and insulation question

I have a 22 year old home. It has a 25 year comp roof on it with 1/4" Foamcore insulation under it. I need to re-roof and wanted more insulation (thinking about 3/4" foam). Can I just run a 1" x 4" around the edge and put new drip edge and sheet over the old roofing with the foam and putt the new reflective comp roof over it? If so, what kind of foam do you recommend? Really appreciate your input. Thanks.

In General questions | Asked By Ted Salyer | Aug 26 15
2 Answers

Extra furring strips into OSB only

I was recently snooping around a house under construction by Habitat for Humanity in Traverse City Michigan. The house is frame 24" o.c. and has two layers of 2" XPS foam (4" total) over the OSB sheathing. In addition to furring strips over each stud, they have attached furring strips between each stud such that there is a furring strip every 12". As far as I could tell, the only thing these additional furring strips could attach to is the OSB. Does this make sense?

In Green building techniques | Asked By Reid Baldwin | Aug 28 15
5 Answers

Do I need to follow the insulation code in any circumstance?

I am converting the sun room to bedroom.
The room is isolated from main building and faced with garage. Only 200sqft room.. no bathroom will be installed in the room.

The room have nothing but the roof above.

In Energy efficiency and durability | Asked By mansig yoon | Aug 26 15
7 Answers

Include provision for future ventilation?

The second story of my old farmhouse is gutted. I am in the middle of running electrical, etc and getting ready to close up the walls. It doesn't need it now, but as I keep working, the house may eventually need a ventilation system. Should I include provisions now while the walls are open for a ducted ventilation system later? Is separate ventilation ducting overkill? What type/size of ducting is typically used for the application? Is it best to locate grilles in the floor or walls?

I have done a lot of reading on the topic but I would like some input others.

In Mechanicals | Asked By Brian C | Aug 21 15
2 Answers

Basement cement floor as shower pan

Our planned basement shower pan is a 5' x 5' area of the poured concrete floor, sloped on all four sides to a central drain and sealed.

This isn't a normal request for a concrete contractor, I'm sure. Has anybody our there done it this way? Are we setting ourselves up for trouble?

(By the way, Plan B is to have the contractor drop the floor a couple of inches in this area and have the tile guy build a conventional mortar bed, Kerdi waterproofing and tile shower pan.)

In Green building techniques | Asked By Esther Streusand | Aug 27 15
8 Answers

Does leaving a service cavity on the inside of a double stud wall make sense?

Would there be anything wrong with the following assembly? From exterior to interior: Siding, furring, rigid insulation, sheathing (air seal and WRB), 2x4 stud wall, gap, netting stapled to inner studs. 2x4 stud wall, and finally drywall. The outer 2x4 stud wall and the gap would be filled with cellulose, but the inner 2x4 stud wall would be empty to allow easy wiring and plumbing.

This design seems to have some clear perks. Removed thermal bridges. You get a service cavity. The inner wall supports the netting, so it won't need excessive stapling.

In Energy efficiency and durability | Asked By John Ranson | Aug 27 15
9 Answers

Wall stack up opinions - using rigid foam as air barrier between double stud wall?

Hi,

I'm in climate zone 6A looking to build a partition wall between an attic bonus room. One side of the bonus room will remain as cold storage, and the other side will be heated by minisplits and resistance backup. I'm looking at building a double 2x4 wall separated by rigid foam. The exterior wall would be framed 24" o.c. to maximize insulation. There will be no plumbing or wires in the exterior wall. The interior framed 2x4 wall will be framed 16" o.c. and will contain wiring, and will possibly be plumbed for a sink.

From cold to warm, here is what I'm proposing:

In Energy efficiency and durability | Asked By Rick Van Handel | Aug 24 15
7 Answers

Anyone familiar with Insultex house wrap?

I was wondering if anyone had any thoughts on this house wrap - http://www.insultexhousewrap.com/

They appear to be making some exaggerated claims and I am not certain that the R-value claimed would be possible.

Any thoughts?

In Green products and materials | Asked By Marcus Sheffer | Jul 31 15
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