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!

4 Answers

Existing basement framing against concrete

We are looking to insulate our concrete basement foundation walls and the 18" wood framed area between the foundation top and the bottom of the floor above it that includes the sill plate. We are settling on closed cell spray foam.

When the house was built the framing for the exterior basement walls were set up against the concrete foundation. There is anywhere between 0 to 1/4" between the studs and the concrete depending on the studs and the texture of the concrete forms.

In Green building techniques | Asked By tyman00 | Apr 11 18
10 Answers

Seal gap between felt paper and interior wall stud cavity?

Hi there,

I'm currently remodeling a house in Austin, and while I have the walls opened up from the interior, I wanted to know whether or not to caulk or use spray foam as a way to fill in the gaps between the sheathing material and the stud walls. In portions of the house there is felt paper for the areas with wood siding, and other areas there is thermo-ply for the brick walls.

In General questions | Asked By homeowner123 | May 11 18
4 Answers

Roof ventilation for an L-Shaped (Plan) house with a shed roof

Climate: 4C (near Seattle)

I'm working on a 1-story home with an L-Shaped plan that will have a shed roof (low side of roof at the interior corner of the plan).
The roof will be constructed with trusses where one wing of the house would have a conventional attic but the other wing would have parallel chord trusses (~18" deep).
There will be a continuous soffit vent at the high and low sides of the roof for ventilation.

In Building Code Questions | Asked By Daniel Stewart | May 13 18
3 Answers

How to insulate tiny hot roof

I live in Michigan. We just survived six months of snow. It's forecast to be 80 next week. Humidity in summer is very high. Those are the unchangeable factors.
I'd like to insulate the roof in my bedroom closet. The house went on the tax rolls in 1896, when insulation wasn't a big concern for the builder.
I had dense pack cellulose blown into the walls. A pro did the attic over the two-story part of the house; another company blew in cellulose into the roof of the 1 and 1/2 story part. All parts of the ceiling in that section are lath and plaster.

In General questions | Asked By AZOgram | May 13 18
9 Answers

Residential peak demand questions

I'm sure most of us have read Dana Dorsett's comments on residential peak demand based pricing that is gaining interest from utilities across North America. Those comments always come up in other members comments so while I feel like I have several comments and questions I try not to derail another persons thread too much. I was hoping to start a thread about that subject so I could ask those questions.

In General questions | Asked By Calum Wilde | May 12 18
4 Answers

Unvented vented roof with exterior rigid insulation

Hey All,

I am doing an energy retrofit on a Zone 5 simple box gable roof. Part of this calls for redoing the roof. I am sold on the exterior rigid foam idea to cut down on thermal bridging and also since my roof slope is very low and the eaves are shallow.

Code calls for R38 but I want to shoot for about R50. The planned assembly going upward is:

1. R20 of fluffy between upper truss cords
2. Structural sheathing with taped seams
3. Air barrier
4. First layer of 3" polyiso rigid foam
5. Second layer of 3" polyiso rigid foam with staggered and taped seams
6. Roof underlayment

In Green building techniques | Asked By jetlaggy | May 12 18
4 Answers

Attic insulation

Hi, My air conditioner doesn't keep the house cool enough in the summer. I live in SW Florida and the house was built in the 80's. The existing blown in insulation has matted down. I'm about to get a new roof. I'm hoping that if I seal the attic cracks plus add inslulation it may solve my problem. I've come across many options and not sure which/what to do, they include which insulation should I use, fiberglass or foam on the floor, should I put a couple of inches rigid foam insulation between the roof and the plywood and insulation on the inside ceiling of the roof between the rafters?

In GBA Pro help | Asked By OntheWater1 | May 11 18
1 Answer

Attaching LP Smartside to ICF house

I'm looking for detailed information on how to install LP smartside on an ICF house. If anyone can help me out, the more information the better.

Thank you,

In Green building techniques | Asked By JBICF | May 12 18
19 Answers

Electric tankless water heater

Do any of the pros out there have a recommendation on a tankless electric water heater? The water comiing in is very cold. Any suggestions would be great.

I'm thinking electric tankless for several reasons:
-Vacation home- long periods of no use, but when the home is being used it's being used by a lot of people.
-It's got PV Panels
-Limited space for tank heater
-Natural gas is not stubbed, propane is available but needs to be trucked in
-I would like to avoid another exhaust pipe through the building envelope

Any suggestions would be helpful, thanks!

In Mechanicals | Asked By David Voros | May 7 18
10 Answers

Can I use my basement as an earthtube?

I am building a house in Zone 5, stick framing, 1.5" exterior outsulation, 2x6 walls with a full basement. As it starts warming up (finally!) I can already sense the second floor is notably warmer than the first floor. Two basement stair openings are wide open, no doors, literally exuding a cool air that lingers in the first floor, almost making it feel like the AC is on. Entering the first floor from outside there is significant temp drop.

In Energy efficiency and durability | Asked By Sal Lombardo | May 11 18
Register for a free account and join the conversation

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