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!

26 Answers

Air sealing and insulating a poured concrete basement

I'm hoping to use poured concrete basement walls and wish to know weather I need to & if so how to air seal them. I want to use rigid rock wool as insulation. I also want all insulation on the inside of the concrete. The concrete basement walls support the outer of double stud walls and the roof/ceilings while interior basement walls support floor framing and the inner of the exterior walls. I
realize, of course, the concrete walls need to be designed to restrain back fill without bracing by the floor as is typical.

In PassivHaus | Asked By Jerry Liebler | Jun 4 12
7 Answers

Dow SIS in zone 5

Take a look at the photos attached. One of the local builders is just using Dow SIS R3 as well as Dow XPS R3 outside of 2x4 construction ... no OSB at all. I asked how he'll insulate to which he replied R13 fiberglass batts. Climate zone 5 which should have R5 outside of the studs to minimize the effect of thermal bridging and condensation ... correct? Is there a fundamental problem with this strategy? Is it really any better than what the other builders are doing with just OSB on the exterior? Seems like it still falls short in zone 5.

In Energy efficiency and durability | Asked By Milan Jurich | Jun 27 12
4 Answers

Who is the manufacturer of the perforated L flashing widely available in the BC area as mentioned in an earlier post?

A gentleman by the name of Malcom Taylor answered to the question on May 15, 2012 and referred to this product.

In Green building techniques | Asked By Ed Harrison | Jun 21 12
6 Answers

Hydronic heat and polyethylene - how to layer the materials?

So, I've read where Joseph Lstiburek implores us to never, ever put polyethylene sheeting beneath the XPS, beneath the concrete (see "Slab Happy" at BuildingScience.com). However, if I place it over the XPS sheeting, then attach my hydronic heat tubing with staples to the XPS as is typically done, what good it the polyethylene sheeting as it now is full of holes?

In Green building techniques | Asked By Kent Jeffery | Jun 26 12
3 Answers

Hunter panels on sidewalls

Additional thought here... should I add another inch of foam prior to installation to stagger the seams? The wall assembly, even using fiberglass in the wall cavities, will be R-30+ AS IS. The roof assembly, assuming 5 inches of foam on the underside of the roof deck, will be around R-50.

Any advice would be appreciated.

Hey folks,

In Green building techniques | Asked By Bill Savoie | Jun 22 12
2 Answers

Flat roof insulation

We own a 100-year-old brick house with a flat (very low slope) roof. The attic space above the second floor goes from about 18 inches at the front of the house to 6 inches at the rear. The roof itself is about 10 years old and in good shape. Despite it being white-coated last year, we still feel a significant heat difference upstairs in the summer.

We are considering putting blown-in insulation in the attic, but worry that without maneuvering room in the attic to verify good coverage we might just be wasting the money.

In Energy efficiency and durability | Asked By David Bush | Jun 26 12
2 Answers

Should I vent a suspended floor over an uninsulated slab?

I live in zone 7. We are building an addition to our house in our barn. We have put 2" of rigid insulation in between the floor joist, seal with spray foam and fiil space under joist with cellulose. Our friend told us we should place a vent under the sub floor to prevent condensation. I'm concerned that putting in a vent will create a draft under the floor. Do we need a vent?

In Energy efficiency and durability | Asked By Justine Wysong | Jun 26 12
1 Answer

What's a good low-VOC shingle that lasts, say, 40 years?

I'm thinking 5 sun tunnels and two skylights would be easier to install on a shingled roof, also the dormer maybe.

In Webinar Follow-up Q&A | Asked By Catherine Tilton | Jun 26 12
9 Answers

Marvin Integrity triple-pane glass?

I was poking around on the NFRC website looking up some ratings, and I noticed under Marvin, they have an Integrity window option in a triple pane window. The ratings are quite good (u= low .20-23) which is quite a bit lower then Marvin's tripane, which tells me they are using fiberglass instead of aluminum clad.
Does anyone know anything about these, and if they do exist currently? I have search everywhere but can not find anything about these other then on the NFRC website.

In Green products and materials | Asked By Jesse Lizer | Apr 28 12
5 Answers

Can I install 1/2 rigid foam to framing and then attach OSB through foam?

We are installing R & R red cedar shingles.

Also, what about Tyvek?


In General questions | Asked By richard difabio | Jun 25 12
Register for a free account and join the conversation

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