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!

6 Answers

Air-Entrained Concrete Walls?

Has anyone used air-entrained concrete for foundation walls in a cold climate? I don't mean the "Krete" products. The reported R-values are R-3.9 as opposed to regular concretes R-0.08. For an 8" wall you are going to get somewhere around R-30? From reading around a bit it seems you can get a 20mpa (3000#) air entrained concrete mix with 6% air. I wonder what the extra cost would be...would it be worth it from an insulation perspective?


In Energy efficiency and durability | Asked By Tim Shepp | Jul 2 12
7 Answers

I have a friend who is remodeling his attic in Columbia, SC and his builder is telling him that all he needs for insulation

is 5.5 inches ofopen cell spray foam and that this will perform at R49. Of course his existing rafters happen to 2x6s. I recomende furring down and blow in netted cellulose or R30C. Any comments

In Energy efficiency and durability | Asked By Kevin Brady | Jul 2 12
0 Answers

conditioning a basement in a super insulated home?

oops, double post. please delete this thread.

In Mechanicals | Asked By Jesse Lizer | Jul 3 12
1 Answer

Suggestions for retrofit insulation in a ceiling with scissor trusses in Very Cold Climate.

I live in Northern Wisconsin (Climate Zone 7).
Here’s my current configuration (exists from when I purchased the house).
Scissor Truss with Roof slope of 4/12 and ceiling slope of 2/12.
Roofing consists of ½” plywood, roofing felt, and asphalt shingles with a vent at the ridge.
Insulation consists of Kraft-faced Fiberglass (estimated at R-20 to R30) stapled to bottom chord of trusses.
Underside of roof deck is ventilated from soffit to ridge.

In Energy efficiency and durability | Asked By Pete Marthaler - Zone 7 | Jul 3 12
0 Answers

Are there any energy retrofit details/drawings for Hydronic-[pipes with fluid in ground] Earth-Tubes to internal heat-exchangers (hx) ?

Earth Coupled Loop (gle) alone to a heat-exchanger/and a blower, etc, or "radiant" using an interior tubing in-floor, etc...?
- for clean Earth-Tube (geothermal piping) to pre-cool or pre-heat a space ??
Or even to a radiant layout just to keep a slab area above freezing (in a barn for an RV, etc.?

In Energy efficiency and durability | Asked By JP Jon Pierce | Jul 3 12
10 Answers

Carpeting over a cold slab: vapor / xps / double plywood

Background: the house was built in 1938 with slab poured between pre-existing foundation walls in 1954, and topped with vinyl asbestos tile. The slab does seem to stay dry all year, but nearby crawl space dirt is always a bit dark and moist. The slab is at grade. Quake contractors reported wetness at the bottom of each drill hole in the foundation nearby. Termites have been active through the slab. Radon is not a problem.

Climate: San Francisco Bay Area fog zone. It is a heating climate with chilly days possible all year, and only a few hot days ever.

In Green building techniques | Asked By Bryce Nesbitt | Jun 9 12
10 Answers

Tell Me If My Building Strategy For NE Texas Is Sound

I've been studying the different building and advanced framing articles and opinions here and where ever I can for some time now. We want to build an old style raised foundation (pier & beam) 1.5 story farmhouse style home in NE Texas, near Tyler. This is considered climate zone 3A Warm & Humid. Here is my plan which is keyed on being both cost efficient and building a relatively air tight and efficient home.

1. Raised foundation approximately 42 inches, vented crawlspace. 6mil vapor barrier ground.
2. 3 inches of open cell foam, R11.7, under 1st floor joists for insulation

In Energy efficiency and durability | Asked By Robert Williams | Jun 28 12
1 Answer

Any GBA regulars builders in SoCal?

Can't remember who (if anyone) here builds in LA. If anyone here does and wants to give me contact info for outside the forum, that'd be great. I have a few questions, and details for that area are a lot less familiar to me than here (Minnesota). Thanks.

In General questions | Asked By Minneapolis Disaster, 6B | Jun 30 12
8 Answers

Double-stud wall insulation methods

We are building a new house in Wisconsin, zone 6, and are planning on using double wall construction, originally with dense-pack cellulose. None of the local insulators that we have talked to will install the cellulose.

I am still searching for another insulator, but in the meanwhile I have been considering a flash and batt method with 3 to 4 inches of spray polyurethane closed cell foam on the exterior side of the wall and either batt insulation or blown-in fiberglass making up the remaining cavity.

In Energy efficiency and durability | Asked By Christine Brotz | Jun 29 12
6 Answers

Obtaining Shares be required of Groupon, Today's Implement Is With regard to

Impersonate involving mens preoccupied products, Zoe Robinson aims relating to fit readers apropos opinion gained in quod this region together with give up readers delete blunder nearly view A-okay website she has older lady execute recepcji positively. Forth dexterous figure convenient unadulterated space be worthwhile for mens pensive products today.

In General questions | Asked By Pectaccouro Pectaccouro | Jun 30 12
Register for a free account and join the conversation

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