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!


12 Answers

Low-slope "warm" roof build-up clarification

Hello
We are advancing on the planning stages of a new build project in climate 4C (near Vancouver, Canada). Thanks to the many articles and Q&As on this site I've got myself comfortable with most outstanding issues we are facing in developing our roof and wall build ups. This is a small building used as a holiday home, not fully occupied in Winter.
With that in mind any feedback from your good selves would be appreciated.
The roof is a mono pitch (shed style) front to back at just 1:12 with no "rafter" space to hold insulation
Build up:
- Exposed 3X8 Douglas fir beams

Asked By Quinn Sievewright | Mar 26 17
2 Answers

EPS foam density for use under concrete slabs and around stem wall

Hi everyone,

I'm right at the point where I need to purchase some EPS foam for our slab foundation / stem wall on a residential net zero project. I've read and posted on the project in the past and there seems to be a consensus that Type II EPS foam should be fine from a compressive strength perspective in both applications.

Asked By Joshua Greisen | Mar 27 17
11 Answers

Building a new house, looking for opinion on insulation/exterior foam combinations

I am currently in the process of designing a new home. I built one four years ago that we have decided is too big and inefficient for what we need. This time around I am looking to build small, simple and efficient. The house will most likely be framed with 2x6 walls, however I would like to maximize R value of that wall.

Asked By user-6801629 | Mar 23 17
1 Answer

How to vent an attic that has no eave?

In an older building. The problem is ice dams more so than energy cost reduction. The roof design is more complicated than I can explain easily here.

I am considering using these vents. however they look designed for new not retrofit construction. Any experience with this type of vent.

https://www.metalera.com/Hi-Perf/Products/Hi-Perf_Intake_Vent.aspx

Wally
thanks in advance

Asked By Walt Ott | Mar 27 17
1 Answer

Critique this rough floorplan

We are in beginning stages of choosing an architect/project manager, but we have some wishes on how we want the floor plan to be.

Being amateurs, I'm sure there are mistakes. Please critique.

Our goals, wants and needs:

- make the house as small as possible, ut with enough room for everything we need/want
For example, we want a study, though that is not common practice here. We took that good practice from USA and like it a lot.

Asked By davor radman | Mar 28 17
1 Answer

Slab on grade retrofit - Climate Zone 3C

Hello all,

Asked By ELLE55 | Mar 28 17
1 Answer

Flooring approach in climate zone 3A basement

Hey folks,

I'm planning on finishing by basement and am looking for some advice on the flooring assembly. I posted something similar about the walls a few weeks back. http://www.greenbuildingadvisor.com/community/forum/energy-efficiency-an...

Some quick information: Climate zone 3a, poured concrete slab, no insulation under slab, no bulk water issues so far, new house constructed in 2016.

Asked By Jamie Royal | Mar 27 17
1 Answer

Dense packing cavities within cathedral vault

I'm preparing to have my attic spray foamed and decided to dense pack the cathedral vault cavities with cellulose. The existing cavities contain batts. Two questions:

1. Is it ok to blow in cellulose on top of the batts or should I fish them out?

2. Should I seal off all the soffit vents (with spray foam) under the eves of the cathedral vault since I'm dense packing the cavities to further prevent any airflow into the cathedral cavities?

3. Should I also spray foam all the soffit vents around the entire house to further promote sealing off any airflow from entering?

Thanks,
Lee

Asked By uberaustin | Mar 27 17
1 Answer

Duct Insulation Sleeves - Black PP or Reflective Foil?

Right out of the gate, I am NOT talking about foil faced bubble wrap duct insulation. This question is specifically in regards to FIBERGALSS INSULATED DUCT SLEEVES. :-)

I see generally two types of fiberglass insulated duct sleeves available; those with some sort of plastic covering and those with a reflective foil type covering.

I would assume the foil covered types might be intended for use in an unconditioned attic with high summer temperatures? But my question applies to using these products within the conditioned space.

An example of both products can be seen here:

Asked By Lance Peters | Mar 27 17
2 Answers

Timber vs concrete uppermost ceiling

Price not being a factor, does either of these options have any significant advantages or disadvantages over another?

I'm building a 2 story brick and concrete house, but am considering of going with timber ceiling under the roof (which could also end up being flat roof).

The local price will be the deciding factor, but only if there are no serious drawbacks to the timber construction.

So, what gives, if anything?

Sound insulation should not be an issue since it's uppermost?
There is not much difference in thermal insulation?

Asked By davor radman | Mar 23 17
Register for a free account and join the conversation


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