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!


2 Answers

Whole house fan with conditioned attic?

We're building a house in the Northeast and the owner is insisting on a whole house fan in addition to central AC.
The attic will be a semi-conditioned space with foam insulation in the rafters. This means no outside air exchange.
Is there a way to put in a whole house fan and vent directly outside?
House is about 3000 sq ft.

In Mechanicals | Asked By Pete Dusenberry | Sep 28 15
3 Answers

Breaking the thermal bridge on the interior

I had a thought about a possible wall construction that I wanted to gauge with everyone. The primary reason I thought of it was for ease of building for a traditional builder - especially flashing complications and building out around windows if there was exterior rigid insulation. It involves using polyiso on the interior of a 2x6 stud wall. In my mind it allows me to use a thinner layer of rigid insulation with higher r value per inch, placing it on the warm side so it retains its r value in Michigan winters (climate zone 5). And it addresses the thermal bridging issue.

In Energy efficiency and durability | Asked By Brian W | Sep 27 15
4 Answers

How to increase the R-value on walls with closed-cell insulation?

I want to increase the R-value of exterior walls that have closed-cell insulation. Rigid foam on the exterior wall will stop the wall drying to the exterior. Is there a way to apply exterior insulation on a wall with closed cell insulation while still allowing the wall to dry?

In Energy efficiency and durability | Asked By Kristen Jessen | Sep 19 15
1 Answer

Mfg. home, block skirt insulation

I am setting a 25x65 mfg home on a full slab foundation in zone 5+, high desert Cascades. I will be putting in a 3 course cement block "skirt" with mechanical ventilation. I am considering installing 2" rigid foam panels 24"x48" attached to the inside of the block skirt. I am looking for heat retention in the winter primarily (-20 on occasion). Will this be worth the effort and expense??

In GBA Pro help | Asked By Robert Holland | Sep 27 15
5 Answers

Can I place foam insulation over linoleum tile in a basement floor?

I'm attempting to remodel a basement that is conditioned space in climate zone 4A (MD).

In GBA Pro help | Asked By John Sullivan | Sep 25 15
1 Answer

Vintage radiant gas heater

Can a vintage radiant gas heater be installed in place of a where a fake fireplace once was ? There is a vent pipe sill in tact . If so is the existing vent sufficient or should an exhaust fan also be installed?

In General questions | Asked By Sonya Sandusky | Sep 27 15
4 Answers

Polyiso along slab edge

There was a picture in the latest Finehomebuilding magazine of a wall profile of a newly built house. I'm going to try and attach it below. It shows polyiso foam along the slab edge of the basement. They used xps under the slab. I thought that because it can absorb moisture, polyiso shouldn't be used anywhere but above grade. From the picture it is positioned right on top of the footing along the slab edge. Is that ok?

In Energy efficiency and durability | Asked By Brian W | Sep 26 15
2 Answers

Ground gutter/curtain drain techniques

I have a 1920s home in Columbus, OH. As is typical of the neighborhood, it's a small footprint (~800 sf) and more vertically oriented (finished space on 4 floors). The house has an existing gutter system, but the west wall (picture attached) still receives water exposure during heavy rainfall. We have an interior french drain system that functions - water will come through the weep holes during heavy rain, but there has not been water infiltration on other parts of the wall.

In Green building techniques | Asked By Matt Bierlein | Sep 24 15
3 Answers

Bathroom ceiling and walls

Working on a project in Quebec. It’s an older home and we are remodeling in steps. We rebuilt one wall of the house, leveled and rebuilt a sub floor in this area. This process required us to tear out the bathroom and two closets on each side of the bathroom. This entire section of the house appears to be an add-on at some point in time and the roofline over this section runs at a slightly lower pitch than the main roof. The ceiling in this area is treated as a cathedral type since the rafters hit the top plate at around 6 feet.

In General questions | Asked By Rob Henderson | Aug 16 15
18 Answers

Air barrier in middle of double wall in mixed climate?

I'm in central Arizona, at the cold end of the Climate Zone 2B range, where I have around four months of moderate heating and five of moderate to heavy cooling.

In Green building techniques | Asked By Jeff Cooper | Sep 20 15
Register for a free account and join the conversation


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