Q&A: A Forum for Green Building Experts and Beginners

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3 Answers

I have a client that is questioning which is a better route...going with ZIP sheathing on the exterior and blown insulation for air tightness, or going with a standard 7/16" osb and open cell foam on the interior for air tightness. Exterior foam would be installed in either situation. Zone 6 for construction.
I was really not sure what is the best recommendation on air sealing. Cost wise, it appears it will be almost the same.

In Energy efficiency and durability | Asked By Jesse Lizer | Nov 16 11
11 Answers

I am trying to get my new built cottage down to .6ACH at 50 pascals. I had my third blower door test done today and initially received good news - we had achieved .6ACH. Then the tester ran the test again at ACH 150 and ran the results through some interpolation software. This test indicated an ACH 2.4 at 50 pascals. Thinking that there might be an error in the interpolation, he then used the duct blaster attached to a window and came up with an ACH 2.8 at 50 pascals.

In PassivHaus | Asked By Steve Snyder | Nov 18 11
16 Answers


How should I air seal and insulate a pine tongue-and-groove ceiling?

My house has a T&G ceiling. Over time the boards have contracted and caused gaps at the tongues and grooves. In a few areas where the ceiling has an angle change, I can see the insulation's kraft paper.

In Energy efficiency and durability | Asked By Walter L | Nov 13 11
10 Answers

I have a 1964 rambler home with a heated room under the garage. The garage slab is reinforced concrete in good condition. I'm planning to upgrade the home's insulation, and this seems like a major area needing attention. There is currently no insulation under the slab, and the room under the garage has a low ceiling (approx 7 ft). The garage has an internal floor drain and is heated, but we keep the temp set just above freezing. The most obvious solution would be to add foam insulation to the underside of the slab, but would this cause problems with condensation?

In Energy efficiency and durability | Asked By Jody Keppers | Nov 16 11

The designers at my firm have enjoyed using Tectum roof deck systems:


We are trying to avoid using XPS because of blowing agent issues, so we were encouraged to find out that Tectum offers an EPS option. Ideally though, they would offer a polyiso option. Since they don't, do any of you know of a similar product out there that offers polyiso instead of EPS or XPS?


In Green products and materials | Asked By Heather Gayle Holdridge | Nov 17 11
1 Answer

I have an air handler in my attic space. The attic is out of the envelope and I would like to build a rigid foamboard box around it to maintain a more even temperature. Should I vapor barrier (Fypar) the inside of the box, the outside, or neither?

It blows heat in the winter and AC in the summer. Of course, its surroundings are just the opposite. Any input would be appreciated.

In General questions | Asked By shane claflin | Nov 17 11
4 Answers

Also, what details are necessary to permanently - place a generator near a home. For example a grounding rod..

In Energy efficiency and durability | Asked By FRancis Gamza | Nov 16 11
12 Answers

I am the un-proud owner of a new home constructed 1 year ago. I have terrible problems with air leakage particularly from the attic where blown cellulose is used. Due to this problem and after reading your columns, I called a BPI certified Energy Audit Company to perform a blower door test.

Prior to testing the company came and turned off all the furnaces and hotwater heater. The gas dryer and stove were not running.

In Energy efficiency and durability | Asked By Kevin Hilton | Nov 16 11
3 Answers

I am building a small 750 square foot cottage and have achieved 1.24 ACH at 50 pascals before applying the drywall/plaster finish. Is there a standard target ACH before the walls are finished? The walls are insulated with foam and I am trying to figure out whether we can achieve .6 ACH by finishing the walls or need to do further air sealing.

In PassivHaus | Asked By Steve Snyder | Nov 16 11
3 Answers

We live in Massachusetts and recently replaced our roof with Ecostar plastic shingles and the rep forced the roofer to expand our soffit vents and ridge vents as part of the installation. We had a much delayed energy audit in the midst of the installation and the recommendations have put us in the middle of what seems to be an experts' dispute. The energy consultant says seal the soffits, spray foam and dense pack the closed rafter area leading from the second floor knee wall to the attic flat.

In Green building techniques | Asked By Stuart Warner | Nov 16 11
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