Q&A: A Forum for Green Building Experts and Beginners

[Click map to enlarge]

Please register for a free account or sign in to ask and answer green building questions.

The usual rules of courtesy apply:
1. Be nice.
2. If you can't be nice, be polite.
3. If you can't be nice or polite — well, please be brief.

To attach a photo or illustration:
Under the box labeled "More explanation," look for the words "File attachments."
Click that, and you should be able to attach a photo.

Thanks for joining the conversation!


4 Answers

Thermal envelope (Zone 4A)

We are finishing off a room in the attic, above an unheated 2 car garage. The room has 5 ft knee walls and a cathedral ceiling. There are no HVAC components behind the knee wall. The floor of the room is already insulated (R30 batt) to the garage below and has OSB flooring. The room will be heated/cooled with a high seer mini-split ductless heat pump. We plan on using open-cell spray foam between the rafters in the ceiling. I believe we have 2 options.

In General questions | Asked By Rob Silbajoris | Aug 27 12
1 Answer

Vapor retarder in exposed structure roof?

i am designing an exposed rafter roof assembly that will have exposed 2x t&g decking as the finished ceiling. Structural is requiring a layer of plywood or osb over the decking for diaphragm. The remainder of the roofing assembly would be 6+" of polyiso, 2x vent furring space, 1/2" osb roof nailing surface, building felt and the asphalt shingles. My question is regarding the space between the structural plywood and the insulation. I was planning on making the plywood an air barrier by taping the joints.

In General questions | Asked By brian elliott | Aug 27 12
5 Answers

Rigid foam over concrete in garage

Im in Albuquerque, NM, zone 4b I believe.

I'm in the process of turning a garage into bedrooms, I want to install rigid foam on the concrete floor and then frame over it to bring the floor level with the rest of the house. Should I place a plastic barrier before the foam, is it needed? Is there a specific tape needed to tape the joints? Should the foam be glued or nailed to the concrete or just float?

Any advice is greatly appreciated, thank you.

In General questions | Asked By Adam Dooley | Aug 27 12
5 Answers

Rigid foam over concrete in garage

Im in Albuquerque, NM, zone 4b I believe.

I'm in the process of turning a garage into bedrooms, I want to install rigid foam on the concrete floor and then frame over it to bring the floor level with the rest of the house. Should I place a plastic barrier before the foam, is it needed? Is there a specific tape needed to tape the joints? Should the foam be glued or nailed to the concrete or just float?

Any advice is greatly appreciated, thank you.

In Green building techniques | Asked By Adam Dooley | Aug 27 12
8 Answers

Will a smaller insulated chimney-pipe create draw problems?

Because my existing brick chimney does not meet the zero-zero clearance insurance specs for Canada, and hasn’t been used for a decade, I am planning on placing an insulated chimney-pipe in for my new wood stove. Unfortunately, a 6″ insulated pipe may not fit the existing chimney, and I have been advised to go with a 5.5″ pipe to ensure it fits.

Might there be any worry of draft (draw) problems with a 5.5″ pipe if my new stove collar (exhaust) is 7″, and my chimney height is 25feet with good outside clearance?

Grateful for advise,

Mike

In General questions | Asked By mike price | Jul 30 12
12 Answers

Is anyone familiar with the Hunter Panel Xci NB insulated panel?

We are planning a new home with our retirement in mind and working for an electric utility I fully understand energy cost are not going down, so I have been studying wall assemblies. I have decided on standard stud construction with 2" polyiso foam on the exterior with either fiberglass batts or sprayed celulose in the cavity. The 2" foam layer meets the Zone 5 requirements according to the information I have been using from this site. The sheathing will be Hardy board or similar product applied over furring strips to provide exterior moisture control.

In Energy efficiency and durability | Asked By Steve Kersey | Aug 23 12
22 Answers

Door to basement or no door to basement?

We've got an unfinished, but nice basement in our 1940s cape just outside of Boston. There's an oil furnace, gas water heater, and gas dryer running down there. There's also one heat duct and a dehumidifier. I've had the door to the basement removed since we purchased the home in the spring and have liked it that way. My wife is telling me to put it back on because it's going to cause our heating bills to be greatly higher than they would be if it were reinstalled. There is no insulation between the floors.

Is she right again?

In General questions | Asked By stephen edge | Aug 20 12
1 Answer

Innie window installation details - a video

See innie window installation details on a new video from the Karuna Passivhaus crew.

Click here to see the video.

In PassivHaus | Asked By Martin Holladay | Aug 24 12
4 Answers

Possiblity of moisture within the layers of polyiso?

I need to meet code (R38- zone 5- on a cathedral ceiling) and would like to do this as cheaply as possible. The exterior of my roof assembly looks like: 3/4 ply, ice and water shield, asphalt shingles. The proposed interior would look like: 1 inch vent (ripped 1x1 w/ 1/4 ply), roxul (r 15), and 3 1/2 inches polyiso rigid insulation. The 3 inches of polyiso would be cut to fit in between rafters while the other 1/2 inch would go over the strapping to give me my thermal break as well as vapor barrier.

In General questions | Asked By derck sturgeon | Aug 25 12
6 Answers

What would our best heating option be?

We live in Juneau, Alaska and our main heating options are electricity from hydro power (14 cent a kilowatt) or oil (diesel #2; $5 a gallon). We have an old oil fired hot water base board heating system we would like to replace with an energy efficient system. We can get a $10,000 rebate from AK Home energy rebate program on renewable energy sources (Air and ground source) and we are also looking at the federal tax credit. And either an air or ground source system reduces our electricity cost by about 1/2 for specialized rates.

In Energy efficiency and durability | Asked By julie bednarski | Aug 21 12
Register for a free account and join the conversation


Get a free account and join the conversation!
Become a GBA PRO!