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14 Answers

How to build a gabled roof on a rigid insulation roof?

Hello to all at this forum. Back in 2013 I posted on my garage build here....

http://www.greenbuildingadvisor.com/community/forum/energy-efficiency-an...

Since a few months now I had started doing some work on my home to increase the insulation value.

I am including a photo of how it is today just before we add the roof sheathing, but I am sort of stuck on how to include a gable roof on each end of the house.

In Green building techniques | Asked By Leon Stepanian | Aug 17 15
3 Answers

Wood stove installation and exterior foam board insulation

If I want to install a wood stove through the wall or the roof and both have 6" of foam board on the exterior, are there additional precautions to prevent exhaust heat duct from melting or causing a fire around the insulation? For example, install one or more layers of cement board over the 6" of foam. Then install through the wall or roof duct work.

In Energy efficiency and durability | Asked By HORST SCHMIDT | Jun 30 12
3 Answers

CMU walls and rigid foam

Retrofit concrete block walls painted inside and out. Exterior foam then rainscreen then siding. Keeping painted block as interior walls.
Do I have to be concerned with the vapor permanence of the foam?
Also, would there be any benefit in using foil faced...other than R-value?
Southern Georgia coast.

In GBA Pro help | Asked By Robert Brown | Aug 29 15
17 Answers

Has anyone had experience with the Unico small duct system?

I was looking at the top finishers for the department of energy's "Race to Zero Student Design Competition" ( http://energy.gov/eere/buildings/2015-results ) and found the winner used the Unico system. http://www.unicosystem.com/the-system/how-it-works/air-handlers/. I recall actually being in a home in Chattanooga once 15+ yrs ago that I believe had one of these systems, but I really know nothing about them. With the problems associated with finding small enough systems for well insulated homes and cost effective systems...does anyone know if I should be looking at this as an alternative?

In Mechanicals | Asked By Andrew Bennett | Apr 29 15
10 Answers

Retrofit / renovation to bring heating costs under control

Hi folks,

Thanks for creating this great resource for newbies like me to learn!

We're actually near Toronto, Canada, but I think you could consider us Zone 6A for your purposes. We bought our ~2000 ft^2 1981 home last year and suffered a horribly cold and expensive winter, so we'd like to take steps to bring that back in control.

In Energy efficiency and durability | Asked By Justin Allport | Aug 20 15
0 Answers

Third-party filters for Zehnder HRV / ERV units?

Besides ordering from zehnder, are there any other filters available that will fit their units? It's not a question of price but more so of long term availability. If they go out of business will I still be able to source filters? I haven't had the chance to pull one out of the packaging and go down to the local HVAC supply house with a tale measure.

I'm an electrician and not an HVAC contractor so I don't understand if these are a common size/shape/build or totally proprietary.

In Mechanicals | Asked By Lance C | Aug 29 15
4 Answers

Rim joist foam and termites

I'm not sure if this would fit better 'Energy Efficiency and Durability' category, but I have a few questions about using foam to insulate rim joists. From an air-sealing and thermal performance perspective foam seems the clear choice. I've read Martin's FHB article and spray foam and cut-and-cobble approaches make sense.

In Green building techniques | Asked By Jeffrey S | Aug 24 15
6 Answers

Insulate cold water pipes

Replaced galvanized pipes wth copper about 15 years ago.
Current hot weather in California causes extreme heat in attic despite solar attic fan and gable vents.
Cold water in pipe line is extremely warm and warm water is now in toilets
Fear warm water may crack toilet tanks and ruin flooring.
How best to insulate these cold water pipes from water getting warm?
Company which did insulation spoke of 3" wall around these pipes.
Can you explain what this is and best way to insulate these pipes?
Thank
Paul

In General questions | Asked By Paul Deleon | Aug 28 15
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
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