Community: GBA Pro help

Q & A Instructions

[Click map to enlarge]

The 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!

3 Answers

Laying drain tile in stone trench under slab- @bottom or center?

In preparing to lay perforated drain tile (4" Schedule 20 perforated pipe) in their trenches under a basement slab, there is a difference of opinion between my contractor and the illustrations in Building Science Corporation "Basement Insulation Systems" research report (2006). My contractor suggests that the filter fabric lay directly on the clay substrate, the pipe directly on top of that, and the 3/4" stone on either side of and above the pipe. Then we'd wrap the fabric 360 degrees around.

Asked By Anita Brosius-Scott | Oct 25 10
14 Answers

Condensation on Cathedral Ceiling

Nine months ago I had a new composition shingle roof installed. When the roofer removed the old roofing, he found there were two layers of comp shingles in place. The slope on the roof is 3/12. The drywall is attached directly to the 2x6 rafters, so no attic space. The underlayment is 30lb felt. The roof faces west. City permit was pulled.

Asked By barbara | Sep 27 09
3 Answers

Is spray foam insulation OK under concrete in basement instead of XPS?

I'm having my existing basement waterproofed (hopefully!) and insulated, and having a concrete floor poured in place of the present moist gravel. My Energy Advisor / insulation guy suggests continuing the spray foam we'll be applying to the walls, on down onto and over the prepared (and drained) gravel under the new concrete, and having that serve as both the waterproof and insulating layer. I haven't read of anyone doing that. The alternative is blueboard (I'm thinking 1" is plenty) and vapor barrier (Tenoarm poly with sealed seams). So, is it OK to use only spray foam under the concrete?

Asked By Anita Brosius-Scott | Oct 13 10
3 Answers

Will foundation insulation inside cause foundation failure in Maine?

Yikes! An entry at ("Building and Environmental Inspection, Testing, Diagnosis, Repair") discusses foundation failures happening after insulating the inside walls of existing foundations - particularly in very cold climates with wet clay soil. Yikes. We're in Maine (pretty darn cold in winter) and our soil is dense wet clay. We plan to insulate the inside of our poured-concrete foundation walls (circa 1936) with spray foam, 3" at the top, 2" down to floor. We'll be pouring a concrete floor too, to replace the moist gravel floor, and insulate (1" or so) under that.

Asked By Anita Brosius-Scott | Oct 13 10
3 Answers

USGBC Green Build expo

Can someone post who, if any of the GBA people will be speaking at the expo and what classes. I attended the Re-green session last year with Peter Yost and it was incredibly informative and interesting.
Thank you,

Asked By benjamin mccarthy | Oct 12 10
2 Answers

A new construction wall in a cold climate

I am building a new addition in southern Ontario and would like to use 1" to 1.5" natural stone veneer for the exterior. Stone veneer would be applied over metal lath screwed into studding.

I would also like to use 1" to 2" of rigid foam insulation as exterior sheathing over 2x6 wood stud walls without an interior vapour barrier.

I was hoping to get some help detailing the wall.

Can the metal lath be applied directly over the rigid insulation and screwed in the studs without any wood sheathing anywhere?

Asked By wayne hutson | Oct 6 10
4 Answers

Basement floor insulation

A section of my house still has an earth floor in a space that's approximately 4 1/2 to 5 feet tall. I had put a sheet of heavy plastic over the earth and then had some crusher dust added to keep it in place. Needless to say, this did not stop the moisture from coming up through the ground. The space is always damp and consequently the rooms above it always have a damp smell in the warmer months and a very cold floor in the winter.

Asked By Gwen Smith-Dockrill | Oct 5 10
9 Answers

What is the best way to insulate interior finished basement walls that have 2" rigid foam on the exterior?

This is in a cold climate and the basement slab is also insulated with 2" rigid foam. Thanks.

Asked By Jason Hackworth | Oct 5 10
4 Answers

Flash & Batt Condensation Issue

I am building a new home in New Jersey. In 2X6 exterior partitions, I am putting 2" of closed cell spray foam insulation followed by 3 1/2" of unfaced fiberglass batt insulation.
During my insulation inspection my local building inspector posed the following question:
What is stopping the moisture/humidity from inside the home from traveling into the wall and condensing between the back of the drywall and the sprayfoam?

Asked By Robert Tonelli | Sep 26 10
2 Answers

Can I put radiant heat under red oak?

The wood has been sitting inside the house for a few years. So I'm sure it has acclimated well.

If it's not quarter-sawn, is that a determining factor as well?

The flooring will be going into a family room with 10-ft ceilings. The radiant heat system will go in the joists below inside the new basement which seems dry as far as I can tell.

Thanks if anyone can give me solid input from experience.

Asked By eric wotzak | Sep 27 10
Register for a free account and join the conversation

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