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4 Answers

How to add cellulose to a wall with existing fiberglass insulation?

I have a 1968 back split in zone 6A (Central NY). The 2x4 exterior walls appear to be insulated with fiberglass. I would like to blow cellulose into the cavities to help reduce air leakage. I know I can blow the walls without removing the existing fiberglass. Should I blow between the fiberglass backing (both foil faced and kraft paper) and the inside sheetrock or keep the vapor barrier in place and blow the cellulose between the exterior sheeting and the fiberglass batt?

Thanks in advance for your help.

In GBA Pro help | Asked By Alwyn John | Nov 21 13
14 Answers

Another conditioned Cape attic

Hello, I have a 1.5 story home, often referred to as a Cape or bungalow, in Ann Arbor, MI. My house was built in the 40s, and recently I've decided to get a new roof and some insulation quotes. I have a single shed-roof dormer on the back where the stairwell comes up, other than that the roof is fairly straightforward.

In GBA Pro help | Asked By Kevin Line | Nov 12 13
3 Answers

Condensation on Insulated Glass windows

Is there any correlation between condensation developing on the inside or insulated glass windows that are energy star rated and the low-e film placement? I was discussing the problem that an architect friend is having with two houses recently constructed using a glass with a low-e coating on the interior face of the windows. I told him that the moisture condensation has to do with ventilation not where the low-e film might be in an insulated glass system. Am I off base?

In General questions | Asked By Philip Koepf | Nov 22 13
1 Answer

How close to the soffit vents under the eaves can I place my exterior wall rigid foam?

I'm doing a curtain wall retrofit, so even though my polyiso is only 4" thick, I'm actually extended a good 8" away from the original wall.

In Green building techniques | Asked By Anthony Zitelli | Nov 22 13
11 Answers

Vapor barrier between ceiling and EPS?

Planning on building a timber-frame. SIPS on side walls. 1x4 or 1x6 T&G run vertically on top of purlins for ceiling. 2x6 or 2x8 stood on edge around perimeter of roof, like a box. ESP the same thickness as 2x material around perimeter screwed down with 1/4" gaps at seams for foam. Seams are foamed and top of seam is taped. 2x4's laid flat, run vertically from eave to ridge, 24" centers screwed down thru foam. OSB or plywood sheathing on top of 2x4's, one of the Grace underlayments next, then fiberglass shingles. Ventiiated soffet and ridge vent.

In Green building techniques | Asked By John H. Stehman | Nov 17 13
9 Answers

One Chicago building envelope system

Thank you all GBA participants who have help educate me on the latest building science and green solutions. I've used quite a lot of this forums past and present posts to make informed decisions on my upcoming rehab project. I have 20 years experience in renovations but this is my first whole house design/build attempting to apply sustainable principles to one of my projects. My last project was in 2005.

In General questions | Asked By Jim Gramata | Nov 17 13
6 Answers

Water-to-air heat exchanger for space heating?

My rough calculation for a heat load shows that I will need about 18,000 BTUs of heat (climate 4C, 2100 square feet, R40 walls, R60 ceilings, triple pane windows, air tight). I have been trying to figure out the best method of heating the home and up until recently I was settled on using a wood furnace as the home will be off-grid.

In Energy efficiency and durability | Asked By Chris Barnes | Nov 21 13
9 Answers

Crawl space ventilating fan

Hello, all --

I have a 625 square foot sealed crawl space that I need to ventilate. I can't seem to find a ducted fan that will suit this application. I'm no internet moron, but maybe I am tonight? What do you all use? My local building code jibes with what Martin wrote about in his article "Building an Unvented Crawl Space."

“a continuously operated mechanical exhaust ventilation at a rate equal to 1 cfm for each 50 square feet of crawl space floor area.”

In GBA Pro help | Asked By Jeff Nelson | Nov 19 13
2 Answers

Rigid foam over first floor insulated slab?

First off, thank you to everyone who participates in this forum! I have found it very useful in answering many of my questions during the pre-construction and now construction phases of my home build.

In Green building techniques | Asked By Keith Andrews | Nov 20 13
10 Answers

Relocating drains to maximize drain water heat recovery

I have a central stack for the bathroom, iron pipe, probably 4" (not a plumber and haven't measured it, but it's big). This is where my DWHR will go, and serving the shower will give me the lion's share of the heat recovery benefits. But I wonder if I could do better.

In Mechanicals | Asked By Nick Welch | Nov 15 13
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