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

Q & A Instructions

[Click map to enlarge]

The GBAGreenBuildingAdvisor.com web site has a wealth of articles on a wide variety of construction topics. Before posting your question, you may want to check out the articles on this page: How To Do Everything. You just might discover an article there that provides the information you seek.

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

If you want to post a question, 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!

10 Answers

Comfort Board 80 vs 110 - density worth extra cost?

For our upcoming house build using 4" of rigid mineral wool we have been quoted for both Roxul comfort board 80 and 110. Over the top of this we will install 2x4 furring and cedar siding.

The 110 has a compressive strength of 1120 PSF at 10% deflection, the 80 is only 439 PSF at 10%, using the 110 will simplify the installation of furring as it will compress less, but I don’t know that the furring installation sub would price their install any differently between the two products. (Furring install not by insulation contractor).

In Green products and materials | Asked By Chris Armstrong | Nov 16 16
4 Answers

Fiberglass window manufacturer comparisons

Has anyone used Duxton Fiberglass windows lately?

I'm also considering Inline, Accurate Dorwin, and a smaller shop called Silex. Accurate Dorwin and Silex use PPG IGU's. Inline and Duxton use Cardinal IGU's. I'm also considering...

In Energy efficiency and durability | Asked By Steven Johnson | Mar 9 17
9 Answers

Radon system design with drain tile to daylight

We are in the process of remodeling our basement and will be pouring a new concrete slab. The house was built in the 1940’s and sits on very dense clay soil. The old concrete has just been removed and we’ve dug down 4” below the top of the footings so that 2” of stone can be placed followed by 2” of EPS, a poly vapor barrier and new concrete. A one year radon test was completed two weeks ago and the average value was 6.6 pCi/l (test completed with all old concrete in place); we will be installing a radon vent prior to pouring the new slab.

In General questions | Asked By Andy Freeman | Feb 16 18
6 Answers

Mitsubishi heat pump defrost mode

I just had a Mitsubishi MXZ-4C36NAHZ with a 24kbtu and 9 kbtu unit installed in my house in Vermont. When the temp drops below freezing, my indoor units blow cold air (as in really cold. Not just a fan circulating air, but COLD). This is a quote from the brochure: "and because the system fan turns on only after the target temperature is reached, it NEVER BLOWS COLD AIR."

1. First if that's true, what's happening?

In Green products and materials | Asked By Joey | Dec 22 15
13 Answers

Crawlspace Beam Layout

Hi Friends,

Long time reader, first time poster. I'm looking for some feedback on my plans on fixing some floor bounce/sag.

House layout is pretty simple, 62x32 with one corner consisting of a 20x20 slab garage. Floor Joists are 2x10s, spaced 16" on center. They span almost 16'. The house has long been neglected, and the crawl was filled with moisture for years. Poor landscape drainage, washing machine leak, and a dryer vented to the crawlspace led to sagging floor joists and a main beam with rotten ends. Plus plenty of mold.

In Energy efficiency and durability | Asked By alexallo | Feb 16 18
7 Answers

Insulating a raised slab

Alright, so here’s one that I can’t find in the great treasure troves of this site: how to handle insulating my raised slab on our new house. Quick details on the project: climate zone 6, 3500sqft, two story, zip-r external insulation/sheeting (R6), fiberglass batts in 2x6 walls, combination vented roof w/ R60 cellulose and unvented roof with R50 foam, low U 4th surface fiberglass windows, and a combination of slab on grade and vented crawl w/ R48 foam. The concrete will be polished as finish floor in slab areas. Heating is entirely mini-split, no in floor radiant.

In Energy efficiency and durability | Asked By User-6804212 | Feb 17 18
30 Answers

Cold weather performance reports from minisplit owners

This morning I drove to town for a dentist appointment, and the digital outdoor thermometer on my Subaru bottomed out at -28°F as I drove through Lyndonville, Vermont.

During the past week, the thermometer at our house hasn't risen about 0°F, even during the afternoon hours. Of course, all of northern New England and the upper Midwest has been experiencing similar temperatures this past week.

So I'm taking this opportunity to ask owners of minisplits to report on how well their systems are working during the recent cold snap.

In General questions | Asked By Martin Holladay | Jan 2 18
3 Answers

Recommended gas furnace for 3550 square foot house

Please let me know recommended gas furnace for 3550 square foot colonial house in Detroit area

In Energy efficiency and durability | Asked By Vissu | Feb 19 18
3 Answers

Insulating a new concrete block (CMU) house

Like all questions (at least here in Citrus County, Florida) this question is also has to consider building codes.

I am planning to build a block home. I would like to take advantage of the thermal mass capabilities by insulating the exterior rather than the interior. Keep in mind I am building on a shoestring (and a worn one at that). I would like to put foam panels on the wall with horizontal furring strips (to attach metal siding), or foam that can be stucco'd over. Will I need tyvek too? Open to suggestions for method and materials.

In Energy efficiency and durability | Asked By D James Fox | Feb 18 18
2 Answers

Being "green" in a public restroom.

What is "greener"? To dry ones hands with the hot air blower, or to use a paper towel?

In Energy efficiency and durability | Asked By KEVIN ZORSKI | Feb 18 18
Register for a free account and join the conversation

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