Community: Energy efficiency and durability

Much of the value of this site is the pooled experience of members and their willingness to share it. This page offers a Community area formatted for Questions & Answers dedicated to Energy efficiency and durability. Other topics appear to the right.

Anyone may ask a question and anyone may answer. Sometimes one of our 15 Advisors may chime in; in other cases, you'll get the wisdom of some of our members who have some experience in this area. We encourage everyone to give us the benefit of both their questions and answers. The usual rules of courtesy apply.

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93 Answers
Serious Windows vs. Thermotech, Fibertec, Inline, Accurate Dorwin

Does anyone have experience with Serious Windows or Canadian fiberglass windows? I'm having a difficult time finding high SHGC windows (with a U-value less than or equal to 0.30) for my passive solar home that are affordable. Looks like the fiberglass windows can give me the performance I'm looking for, but I can't find any local installations to inspect the quality of manufacture.

Asked By Claire Anderson | Oct 1 09
1 Answer
Injected foam insulation

I am trying to get some ball park about injectable core foam for hollow concrete blocks.

I have an existing home in South Fl houses faces east and west. I am considering having the walls filled with inject able core foam. The only insulation that I think is in the walls is the brown paper with foil on back. The house is CBS built in 2001.

Asked By Roberta Atkins | Sep 1 10
8 Answers
Building vent chutes in a cathedral ceiling

Could someone build and / or be wise to build vent chutes for a cold roof in a cathedral ceiling out of strips of 1" foam ( butted up against the sides of rafters and the underside of the roof sheathing) and then attach a sheet of 1" or 1 and 1/2' foam under the strips forming a chute? Then fill the remaining cavity with fiberglass?

Yes, yes, yes people don't like fiberglass. I personally think spray foam is not cost-effective. The purpose of my proposal is to 1. create the vent space, 2. gain a bit on R-value over FG alone.

Asked By Joe Barnes | Aug 26 10
11 Answers
R45-50 thick walls, rigid on outside or closed cell spray foam on inside with cellulose?

I'm planning a super insulated, super tight house in upstate New York. I've seen lots of double wall details using 2-3" of spray foam on the inside and 9-10" of cellulose to fill the remainder. I have not seen any details using 2-3" rigid insulation on the outside of the sheathing with 10" of cellulose in the wall cavity. Would both types of walls perform similarly? Is there an advantage to one over the other?

Asked By Jill | Apr 1 10
11 Answers
Energy Efficiency of conditioned crawlspace

I think I am sold on why a crawlspace should be conditioned, especially in my area (Houston). However I'm not sure I understand the efficiency part, especially since I will have to heat/cool that space. It is a 4300 sq ft 2 story house (about a 2500 sq ft footprint) and the crawl space is abouit 4 ft. So is that a negligible heating/cooling cost (equipment and heating/cooling bills) compared to a vented space? How exactly do you compare the efficiency of one vs the other?

Thank you

-chris

Asked By Chris Morton | Aug 26 10
4 Answers
Rigid Insulation on the interior

This could be a newbie question or just so utterly wrong that even newbies don't ask it, but I'm remodeling the upstairs of our older home (60-70 years with 2 x 4 walls). Living in Wisconsin we have fairly high winter heating bills. I was considering adding rigid insulation (xps) between the vapor retarder for the fiberglass batts and the drywall as opposed to furring out the walls to add more insulation. From the limited amount of reading that I've done the vapor barrier is already meant to be less permeable then my exterior so the wall should "air out" to the exterior.

Asked By Joe Gilman | Aug 25 10
3 Answers
Installing Fiber Cement Siding over Rigid Foam

Does anyone have a best practice recommendation for installing fiber cement siding over rigid foam?

Asked By Victor Burgos | Apr 20 10
3 Answers
Open-cell foam sprayed on the underside of roof sheathing

I was at a house recently. It was a 2-story built around 1920, so it probably had 2 x 4 rafters. In speaking with the owner he said that he open-cell foam sprayed on the under side of the roof deck. I asked if I could see it.

What I found was that the open-cell foam was left uncovered, with no fire barrier. I do not know how thick it was, but doubt it was much over 4.inches. I am in Nebraska to give you an idea of the climate.

He was told open-cell was used as it will allow any roof leaks to show up.

Asked By Robert Hronek | Aug 24 10
5 Answers
Unvented Attic with Batts

We are working an existing house that has an unvented attic. There are fiberglass batts installed in the roof rafter bays. We would like for the attic to be within the thermal envelope of the house as the Owner stores books and research in the attic.

One option we are considering is to leave the fiberglass in place and cover with2" unfaced vapor semi-permeable rigid foam with taped seams.

Asked By Chris Harris | Aug 23 10
11 Answers
Questions about the building assembly details and insulation strategy for a Colorado house

I live and build in Durango, CO (Zone 5a), and am currently building a custom home for some folks. My insulation contractor is proposing a few things that make me go "hmm."

He wants to use a flash approach to the walls and spray a thin coat (about 1") of open-cell foam against the sheathing to seal the cavities and then fill the rest with loose fill fiberglass netted. In the room above the garage we have a cathedral ceiling which he wants to spray 4" of closed cell foam and fill the rest with fiberglass batts.

Asked By Greg Mantell-Hecathorn | Aug 19 10