Community: Green building techniques

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!


10 Answers

Small addition with helical pile foundation in Toronto Canada

Hi GBA,

I am an architect in Toronto. My client is a contractor who wants to build a small one storey addition using helical pile foundation instead of continuous foundation to save on cost.

The finished floor is raised above the grade by about 21".

My questions:

-Can I use chicken wire to support the fibreglass insulation in the floor joists as it would be difficult to finish the underside of the floor with plywood I think
-Do I need a air-barrier like tyvek under the fibreglass insulation

Asked By Lowell Lo | Apr 22 18
5 Answers

Foundation Waterproofing & Insulation Treatment

My new home design has an 8' basement and an attached garage with a 4' foundation. Is the garage foundation poured at the same time as the house or separately? On the basement foundation walls I'm planning to use spray-on waterproofing, board insulation, and a dimple mat. I'm not sure how to treat the vertical edge condition where those materials would start/stop. I used Sketchup to help myself visualize what's happening. Do basement exterior materials wrap under the garage footings and continue along the basement under the garage slab?

Asked By Bryanw511 | Apr 20 18
3 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.

Asked By tyman00 | Apr 11 18
36 Answers

Brick house insulation

All,
First of all, I wanted to wish everyone Happy and Prosperous New Year!
I would like to ask for an advice regarding a wall cavity composition. I am in Westchester County, 30 miles north of New York City, climate zone 4. I am about to acquire a brick house (tiny brick, maybe 2-3 inches thick). Single wythe, I believe. I think that brick is just decorative and is not load bearing at all. Only cinder blocks in the basement support the floor joists. Second floor ceiling joists are supported by wood framing.

Asked By Sebastian Smith | Dec 29 17
9 Answers

ZIP System R Sheathing vs Roxul Comfortboard

Building in the Canadian Rockies, so climate zone 5-6 ish.

Up until now I have been considering building a 2x6 exterior wall (with Roxul Comfortbatt in the stud bays) covered in 1/2" exterior plywood, installing a air/moisture barrier from Stogard over the exterior of the plywood sheathing and then fastening1 1/2" Roxul Comfortboards over the Stogard.

Asked By Scott Wilson | Apr 13 18
13 Answers

Thermal breaks when enclosing porch

I have a stone porch in front of the house (6'x25') in lower New York (climate zone 4), that is surrounded on three sides by the house and garage (fiberglass batt insulation c.2005 construction). Only the front is exposed and open. The floor is stone, presumably on a concrete slab. The siding is cedar shakes, with a 6" protruding stone chair-rail around 3' off the ground in it, and stone facing below that. The roof line continues down over this area (with a nice bead-board ceiling with high-hats in it).

Asked By j star | Apr 17 18
13 Answers

EPS, XPS or Polyiso for exterior rigid foam?

Last week I got some great information from this board on my "Taping seams of roof sheathing" question. There was some thread drift there and we started talking about exterior foam and someone suggested I use Polyiso instead of XPS for my exterior foam.

Asked By Steve Mackay | Mar 28 18
10 Answers

Foundation insulation & moisture protection

I would like to insulate and protect my basement foundation walls using a water based spray on waterproofing, XPS insulation board, and a dimple mat. In what order would they be fastened to the wall? I feel like the insulation should go on after the waterproofing for it to be effective as an insulator.

Asked By Bryanw511 | Apr 10 18
29 Answers

Rainscreens with Roxul Comfortboard IS?

Hi all.
I am planning out my wall construction for a home in zone 6. Not much rain (15" annually), but plenty of snow in winter (56" annually). Hot (and mostly dry) in summer (80sF to low 100s), cold in winter (mostly lows in the single digits, but sometimes minus teens F). My house will not have much direct sun due to northern exposure and tree shading.

All that said, here is the wall I am considering:
- wall board
- 2x6 fir studs on 16" centers, Roxul Comfortbatt (R23) between the studs
- OSB, taped and sealed for my air barrier
- house wrap for vapor barrier

Asked By Mike B | Mar 20 16
10 Answers

Rigid foam and dimple mats

My concrete contractor will be applying bituminous waterproofing tar on the outside of the basement walls up to grade. We are considering putting 4" of rigid to the exterior of the concrete after that. Someone advised us to also put up a dimpled waterproofing membrane, but is his necessary if we are applying the 4" of rigid foam?

Asked By Nina in CNY | Sep 30 17
Register for a free account and join the conversation


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