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

[Click map to enlarge]

Advice can depend on climate -- Please specify in your question.

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!

Ask a Question >

3 Answers

Basement finish floor, slab on grade

With the help of this site I insulated and framed my basement (90 year old house, 8-9" concrete walls). I did 2 inches of XPS (EPS in hindsight would have been greener but I had a deal on some XPS), 2x framing with Roxul R-15 in between 2x. Rock is next and then floors.

In General questions | Asked By Sean Cotter | Mar 1 15

7 Answers

Buying a house and want to make it super efficient. I have some concerns about the attic. Can you help?

I am about to close on a house that was built in 1972. It is in Longview, Texas. It is 2100 sq. ft. The garage was made into living space at an unknown date. Has a 3.5 ton central air unit and electric furnace for heat (inspector said that is too small and likely was in place before the garage was converted). Flex type ducting in the attic. My goal is to eventually do the entire place from top to bottom, as I can afford it, and make it cheap to heat and cool. I have several plans in mind. Insulation of the attic I think will be my first step.

In Energy efficiency and durability | Asked By Sam Vail | Feb 26 15

5 Answers

What is a correct way of fastening two layers of 2" rigid insulation to the exterior of a 2x6 wall?

I would like to know the correct way to fasten two layers of rigid foam insulation where the total thickness is 4". I am concerned that when hanging this thickness of foam it will be difficult to be sure that the siding application is secure. We will be using HardiePlank horizontal lap siding. This is a form of cement board and heavy on it's own. Any advice.
Thanks

In Green building techniques | Asked By william dempsey | Feb 26 15

1 Answer

Pier and beam — insulation under floors/house?

I live in a 645 s.f. two-story home on pier and beam. It is not well insulated, not winterized and not the most precise construction. It is about 20 years old and we just purchased it a year ago. My husband and I had plans to work on it to get it better insulated and heated, but he passed away suddenly and now I am trying to think of the things he mentioned we might try.

In Energy efficiency and durability | Asked By Jennifer Shrift | Mar 1 15

2 Answers

Any experience with precast basement walls?

We are planning to build a new home in southeastern Pennsylania. We are very concerned with paying close attention to energy efficiency and using energy efficient products, systems and techniques. One of the proposed contractors has suggested using precast concrete basement walls. His selling points are price, energy efficiency (R-22), built in waterproofing and expediency. He feels there is no comparison when you look at precast versus ICF walls for the basement. Does anyone have experience with these products. Any help will be appreciated.
Thanks,
William

In Energy efficiency and durability | Asked By william dempsey | Mar 1 15

0 Answers

Any new information on using fog machines to pinpoint leaks?

Here's the article.
http://www.greenbuildingadvisor.com/blogs/dept/musings/pinpointing-leaks... several questions were posed with no answers:

Pinpointing Leaks With a Fog Machine
Builders can use theatrical fog to find envelope holes
POSTED ON SEP 18 2009 BY MARTIN HOLLADAY, GBA ADVISOR

Tell-tale fog. Once a theatrical fog machine has clouded the interior of a pressurized building, builders can find envelope leaks by looking outdoors for the escaping fog.

In Energy efficiency and durability | Asked By David A Flannery | Mar 2 15

6 Answers

Converting fiberglass+plastic basement insulation to rigid foam - worth it?

Brick/masonry house with a concrete, finished basement.

The foundation walls are insulated with R11 fiberglass, topped with plastic, and covered with drywall.

I've read vapor barriers below-grade are bad & that wet fiberglass is useless as an insulating material.

Am I overthinking the usefulness in tearing down the drywall in the basement, removing the fiberglass/plastic, and installing rigid foam boards instead?

In Energy efficiency and durability | Asked By Jeff Watson | Feb 28 15

41 Answers

Best way to have a wood fireplace?

We are building a custom house, and are nearing our final planning stages before bids with our architect. We are planning to have a wood fireplace on the ground floor, within the building envelope. When it is burning, it will likely to burned with any glass doors on the fireplace open, for aesthetic reasons. It is only going to be used as a heat source as an occasional backup. What are the best ways to minimize the energy problems of an wood fireplace? It'll probably be a zero-clearance type of fireplace. My husband will not agree to a gas or wood stove, so don't even suggest it!

In Energy efficiency and durability | Asked By Clara Kim | Feb 22 15

9 Answers

Foil-faced batt insulation effect on wall construction?

I’m in the process of planning energy retrofit for my house located in Philadelphia (zone 4A)
Existing wall construction consists of t1-11 over 2x4 framing with foil-faced batt insulation. The plan is to add 2 layers of 2” polyiso to the exterior taping joints making polyiso my WRB. Is there any concern that moisture trapped in the wall cavity won’t be able to dry to the interior due to foil faced batt insulation?

thanks!

In GBA Pro help | Asked By Michael Kalustov | Feb 27 15

5 Answers

Dense packing cellulose - height of cavity

What are the thoughts out there on how tall a cavity in this double stud wall can be before there are concerns?

Here's the wall:

There's an outer 2x6 wall, 16" O.C., and an inner 2x4 wall also 16" o.c. There's a 6" space between the inner and outer studs, for a cavity depth of 15".

The first floor walls are 9' tall, with an 18" deep floor truss above. In other words, there will be a 10.5' height of cellulose. The second floor is about 8'4".

In General questions | Asked By Graham Fisher | Feb 28 15

Register for a free account and join the conversation