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!

6 Answers

Effectiveness of sheep's wool as a radiant barrier

In short, my question is: what is the emissivity (or reflectance) of sheep's wool insulation?

This article gives an R-value of 3.5 to 3.8 per inch for wool: http://en.wikipedia.org/wiki/Wool_insulation
This article gives an R-value of 3.7 per inch for cotton: http://en.wikipedia.org/wiki/Building_insulation_materials

In Energy efficiency and durability | Asked By Woodland Dweller | Nov 18 13
5 Answers

Any discussion groups in CT?

I'm wondering if there are any discussion groups/professional associations in the CT area?

In General questions | Asked By Benjamin Bogie | Nov 18 13
4 Answers

Insulation of concrete walls (above and below grade)


My wife and I, after a lengthy search, have finally found a house that meets our wants and needs. However, I have one potentially serious concern, and that regards how the contractor insulated at least some of the 1922 home's concrete walls in the recent to-the-studs renovation. To be clear, in addition to the basement, this home has above-grade concrete walls as well (with a stucco exterior). I'm attaching a picture to show a portion of the main floor when taken down to the studs.

In GBA Pro help | Asked By Doug Elliott | Nov 19 13
4 Answers

Is it possible to install new stud frame and window from inside instead of ripping split face stone outer wall down? What about the wall ties?

Termite damage on inside stud wall around window.

In General questions | Asked By Thomas Conley | Nov 19 13
1 Answer

I want to add insulation to the cathedral ceiling in my shop

About 20 years ago I built a workshop. It has a metal roof installed over 1X4 strips that are nailed directly to the 24" oc 2X10 rafters. I had a local insulation installer spray cellulose insulation directly against the metal roof. The insulation began to fall off almost immediately and today approximately 1/2 of it is gone. I would like to put more insulation overhead and have considered either fiberglass batts or spray foam. I have always been taught to provide an air space above fiberglass but there is not an easy way to ventilate above this cathedral ceiling type area.

In GBA Pro help | Asked By Anthony Bright | Nov 19 13
14 Answers

Using Reclaimed Fiberglass (?) Faced Polyiso

I have access to some 3.5" reclaimed polyiso that I believe has a fiberglass facing on each side of the board. At least, I think its fiberglass. The best way to describe the facing is it kind of reminds me of landscape fabric.

My intention was to use the foam as sheathing on the walls of the house I'm building. I am just down the road from Urbana, IL (Climate Zone 5A....but feeling a bit more like 4A at times).

My wall assembly (from interior to exterior) is as follows.....
- drywall
- 2x6 with mineral wool batts (R-23)
- ZIP sheathing
- 3.5" polyiso (~R-22)

In General questions | Asked By Robert Kohaus | Nov 18 13
12 Answers

A resilient double-stud wall for the West coast

After reading Martin's excellent blog and the interesting discussions that followed on the potential vulnerability of sheathing in thick walls, I wonder wether this assembly might result in a good resilient wall for the PNW climate?

- Drywall
- 2"x4" load-bearing framing insulated with batts or cellulose.
- plywood sheathing as air seal and to provide shear for seismic.
- 2" gap (insulated as above)
- 2"x4" framing (insulated as above).
- 1"x4" skip sheathing at 12" o.c.
- Rain screen strapping.
- Siding.

In Energy efficiency and durability | Asked By Malcolm Taylor | Nov 1 13
10 Answers

How bad are portable heaters for a healthy house?

We have hit cold weather (well, cold for Georgia), and my builder wants to use propane or kerosene heaters to finish out the drywall work and interior painting.

Because we are trying to build a low VOC healthy house, I am reluctant to introduce all the chemicals that go along with combustion. I would prefer electric or indirect heat, but those options don't seem to be too popular with our local rental stores.

How bad are the combustion heaters? Will I regret using them? Are there any practical options I'm not aware of?

In Green building techniques | Asked By Steven Knapp | Nov 12 13
13 Answers

Is installing XPS Rigid Foam from inside wall safe from moisture problems?

I have 2x6 framed walls in my home. R-19 kraft faced. Outside sheathing is OSB that has Builders Felt with Metal Lathe attached and then Stucco. I am pulling down sheetrock on inside to seal air leaks with elastomeric caulk. Can I seal each "bay" with caulk and then press in 1" XPS Rigid Foam for even tighter ?

In Energy efficiency and durability | Asked By Roy Wall | Nov 18 13
3 Answers

Condensation on exterior stone patio

This may be the wrong area to ask this, if so, sorry. But, I live in North Texas where the temperature can swing from significantly from day-to-day and the humidity can sit at around around 70% with very little wind.

The problem is it creates heavy condensation on my 3 sided smooth stone tile patio. I don't have problems with freezing temperatures creating ice. But above freezing the water creates a major problem when trying to walk on the surface. Lots of slipping around. I have a fan that helps but I'd like to try and prevent the the formation.

Any suggestions? Thanks in advance.

In Energy efficiency and durability | Asked By V Larson | Nov 17 13
Register for a free account and join the conversation

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