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2 Answers

Does Loosefill Attic Insulation Require an Air Gap Between Insulation and Roof Decking?

Does loosefill attic insulation (specifically fiberglass or cellulose) require an air gap between the insulation and roof decking to be effective? Once I've installed baffles to protect the soffit vents I would like to blow insulation all the way to the roof decking at the eaves on houses with shallow pitch roofs. My goal being of course to maximize R-value. Any reason not to do this? Thank You for sharing your knowledge.

In Energy efficiency and durability | Asked By Randy Ransom | Aug 29 12
9 Answers

Drafty Gas Fireplace Insert

In the winter (Alberta) we get huge drafts coming in the grills of our gas fireplace insert. I've noticed it when it's not in use, especially at night but it seems inconsistent and not necessarily predictable by the temperature or audible wind. From the outside there is a fresh air intake on the chimney and there is a metal chimney exiting the top of the old stucco chimney.

What can I do here? Who would I even call to look at it? My husband likes the fireplace but I am really concerned about the draft coming in when it can be -30 C here and our winter is long.

In General questions | Asked By New to North-Central Alberta | Aug 26 12
5 Answers

Broan automatic make-up air damper with a dedicated HRV?

Cold climate zone 5 - central OH. Mechanical ventilation strategy being considered for the new build is as follows:
- Balanced system featuring an HRV with "dedicated" ventilation ductwork. HRV being considered is the RecoupAerator 200DX equipped with an ECM motor from UltimateAir. Pulls stale air from bathrooms and laundry rooms and provides fresh air to the great room and bedrooms.

In Mechanicals | Asked By Milan Jurich | Aug 26 12
1 Answer

How to calculate R-value of attic insulation?

Hi there -

My wife and I are in the final stages of completing a super-insulated house near Ottawa, Canada. I have requested that the attic be insulated to R-80 with blown cellulose. While in the attic yesterday installing some cabling, I had a chance to measure the cellulose. It was installed about a month ago, it is very even, but is only 16" in depth, more or less.

From what information I have cobbled together from the net, this corresponds to about R-60. Am I correct or I have I not accounted for something (such as settling)?

Thanks in advance.

John Scime

In Green building techniques | Asked By John Scime | Aug 28 12
1 Answer

Will VOC's from paint travel through flooring of apartment?

I have a severe allergy to anything new (carpet, paint, most flooring, etc.). I currently live on the 2nd floor of a 3 story apartment building. I just found out that the tenant above me will be moving out - so the apartment will be painted and prepared for the next tenant. My concern is that the VOC's from the new paint will pass through the flooring into my apartment. Is this something that occurs rapidly almost effortlessly, or something that is rather slow? I really appreciate your time.

In Interior design | Asked By Trent Pain | Aug 26 12
3 Answers

Thermal bridging - Cold climate

I am building a cabin and am concerned with thermal efficiency in my envelope. I know this topic has been disclosed in depth but I was unable to find the right answer..

So, I am contemplating three wall assemblies. What you your opinions? Option C probably costs the most...

[Option A - Exterior Rigid Insulation]
Plywood good one side interior finish
6 mil Polyethylene Vapour barrier
2x6 studs @ 24 inch o/c
RSI 3.52 (r-20) Batt insulation...perhaps cellulose insulation
Rigid insulation c/w spunbonded olefin facer (mb)

In Green building techniques | Asked By david lam | Aug 26 12
10 Answers

Cold climate, hip roof, venting the rafters, insulating the rafters

House will have wood heat (drying out the building). Current framing includes 2x6 studs, 2x6 ceiling to attic, hip roof (5/12), 2x8 rafters, open soffit venting, two-foot overhang. Large variation from one end of the 42x28 building to the other -- enormous Sun on south side, full shade on north end. (42-foot length is north-south).
-- Hip roof -- I'll drill large holes to open one creeper to another creating air movement up the hip to keep the sheathing dry and cold in Winter.

In General questions | Asked By Lewis Matson | Aug 26 12
1 Answer


I want to put EPS on top of an underinsulated/unvented roof, then plywood and asphalt shingles. Am I right that this can be done without sleepers (nailers) going through the foam? Would 5/8" plywood be thick enough for shingle nailing? Any thoughts on how thick the foam could be? The cieling height is too low to add venting or insulation from the inside.

In General questions | Asked By william goodwin | Aug 28 12
4 Answers

Thermal envelope (Zone 4A)

We are finishing off a room in the attic, above an unheated 2 car garage. The room has 5 ft knee walls and a cathedral ceiling. There are no HVAC components behind the knee wall. The floor of the room is already insulated (R30 batt) to the garage below and has OSB flooring. The room will be heated/cooled with a high seer mini-split ductless heat pump. We plan on using open-cell spray foam between the rafters in the ceiling. I believe we have 2 options.

In General questions | Asked By Rob Silbajoris | Aug 27 12
1 Answer

Vapor retarder in exposed structure roof?

i am designing an exposed rafter roof assembly that will have exposed 2x t&g decking as the finished ceiling. Structural is requiring a layer of plywood or osb over the decking for diaphragm. The remainder of the roofing assembly would be 6+" of polyiso, 2x vent furring space, 1/2" osb roof nailing surface, building felt and the asphalt shingles. My question is regarding the space between the structural plywood and the insulation. I was planning on making the plywood an air barrier by taping the joints.

In General questions | Asked By brian elliott | Aug 27 12
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