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1 Answer

Can 1.5" and 2.0" unfaced XPS be used as a continuous rafter baffle?

I am considering using either 2.0 or 1.5 XPS as a continuous rafter baffle (from soffit to ridge vent) using a 2" vent between the XPS and the the roof deck. The rafters are nominal 2x10s and the underside of the rafter will be insulated with Roxul and then covered with finished plywood with a high quality latex paint (Class II or preferably Class III vapour retarder). I have only seen 1" XPS recommended by GBA. Can a thicker board be used or is there concern re: drying to the exterior given the relative impermeance of the thicker board?

In GBA Pro help | Asked By Andreas Seibert | Oct 18 16
1 Answer

Replacing siding on an old Toronto house


I need to replace the siding on my house. I've read through this article, but still have some questions:

Some info:

In General questions | Asked By Jon Haque | Oct 18 16
11 Answers

Insulating an addition built on piers and insulating corners

I am starting a 16' x 21' addition that will be supported on 8' tall block/brick piers. The floor will be framed with 11 7/8" I Joists. I contacted an insulation sub for the insulation work. Here are the details:
23/32" plywood sub floor
11 7/8" I joists
Sub will apply R30 of Icyene open cell foam to bottom of sub floor (leaving approx 3-4" air gap to bottom of joists
I will install 2" XPS foam, then 15/32" ply, Tyvek taped for air sealing, and vinyl soffit,

In Energy efficiency and durability | Asked By Dave Otto | Oct 13 16
14 Answers

Add rigid insulation to a 2x4 ceiling with an existing polyethylene vapor barrier?

I've been creeping around this website for years. I love reading random articles and questions and learning this stuff for fun.

Zone 6. We live in Southern Maine (Scarborough to be exact, stop by and say hi!).
Our "play room" appears to have been built (or renovated) as part of the garage addition, date unknown. Our house is 1960ish.

- (Section A) About 300 sq.ft. of the room is a flat drywalled ceiling, 8' tall. 2x6 framed ceiling. "Attic" space

In Green building techniques | Asked By Seth Fernald | Oct 3 16
1 Answer

ERV ducting options for existing construction?

I have taken Martins advice from a past discussion and added an ERV to our home. Currently the ERV is setup in the easiest install method by adding the fresh air and exhaust air ducting from the ERV to our return air for our furnace. Our furnace blower has an ecm blower so we are not taking a huge power hit as it pulls about 100 watts. The drawback to this is that we have two independent HVAC units serving the home, each on opposite ends of the two story house.

In GBA Pro help | Asked By Jeremy K | Oct 17 16
2 Answers

Insulated Slab - Entrance and Edge Details

I am working on my first Insulated and heated slab for a garage addition. We are focused on getting the details right. To start we are in Northern NJ (Climate zone 5/4 Marine) We installed 2" XPS down the inside of the stem walls to the footer. Under the slab we have 2" XPS sitting under the Vapor Barrier and wire mesh and above the crushed stone capillary break. We are running into an quandary with the edge details:

The mason is insisting that we need to

In Energy efficiency and durability | Asked By David Colin | Oct 17 16
8 Answers

Old, empty house — preventing mold

I have a small, old house in Transilvania (Romania) that is empty. The windows do not close well,

In Energy efficiency and durability | Asked By Sue Park | Oct 15 16
2 Answers

Finding an engineer

I would like to put 8" of rigid foam over a gambrel barn roof, with long fasteners. However, I cannot find a standard guide to the numbers and spacing of screws for the roof. I was going to do screws every 12x12" (horizontally and vertically), but am concerned this may not be enough.

How do I go about finding an engineer to help calculate the appropriate quantity? This seems like a pretty specialized application, and I would want to use someone with experience. Is there a guide somewhere that lists names and numbers of companies who specialize in this area?

In Green building techniques | Asked By John P. | Oct 17 16
4 Answers

Underfloor hydronic: foil faced insulation or aluminum diffuser plates?

Hello: I have a hydronic underfloor system (double pex-piping within floor joist space). The installer used NEITHER diffuser plates to hold the piping NOR reflective insulation. The performance has been disappointing and after having read many of your posts and Q&A I am convinced I should do one or the other at least. The insulation in the joist spaces is R11, kraft paper facing to the basement.

In Mechanicals | Asked By Trevor Laubenstein | Oct 14 16
8 Answers

How best to install HVAC return duct on outside of house?

Basic facts: 3 level house built on a down slope hillside lot in 1994. HVAC zone one covers main and upper floors. Zone two heats lower floor bedrooms. Equipment room located on lower floor. Climate zone 3c---SF Bay Area home. Large SW facing windows heat up main floor (family room) and upper floor master suite.

In Mechanicals | Asked By Joe Geesman | Oct 4 16
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