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3 Answers

Open-cell foam in an unvented cathedral ceiling

I'm getting quotes from contractors right now to insulate a small cottage with an unvented cathedral ceiling using 2x10s. I'm in zone 3C.

One contractor has suggested spraying 5.5" of open-cell foam between the rafters and calling it a day. I asked if we could just fill the entire 9.5" cavity and he said, "You achieve maximum efficiency @5.5. Any more is overkill. It will expand a couple more inches as we will not cut it but leave the excess."

Code requires R-30 for ceilings around here.

I may be wrong but doesn't more insulation mean higher R-value?

In Green building techniques | Asked By Nicholas Jensen | May 13 13
3 Answers

Can I use Zip System R sheathing if I keep the relative humidity low?

I'm quite drawn to the Zip System R sheathing for reasons of installation, cost, and ability to install cedar shingles without horizontal strapping every 5". Unfortunately, based on the many blogs and discussions from this site, it seems that even the thickest Zip R product (1" polyiso) is insufficient exterior foam sheathing for climate zone 6a, given our preferred wall system (2X6, dense packed cellulose).

In General questions | Asked By Mike McKernan | May 13 13
13 Answers

Interior Air Barrier

I'm trying to decide which product to use for my interior air barrier. I'm constructing a double stud wall system and intend on placing my interior air barrier on the outside of my inside stud wall. My choices are..

- Certainteed's Membrain
- Siga Majpell 5
- ProClima Intello +
- ProClima DB+

In Green products and materials | Asked By Brian Beaulieu | May 3 13
14 Answers

What needs to be pressure treated?

I'm exploring the use of a wood basement for my "dream house. One possibility is a double wall with the outer wall framed 12" OC and an inner wall framed 24" OC. The outer wall would, of course be sheathed with 'foundation grade' pressure treated plywood and framed with similarly graded lumber. The outer wall will sit on footings and outside the perimeter of the basement's slab floor. The outer wall may extend higher than the inner, to the bottom of the sub floor.

In General questions | Asked By Jerry Liebler | May 9 13
2 Answers

Code question regarding HRVs and bathroom fans

Everything was going well in our green home planning process until a short conference call with our mechanical contractor today.

His assertions:

1. our home will be too dry (we are omitting a humidifier)
2. our bathrooms still need exhaust fans (we are installing an HRV) in order to pass inspection and meet code
3. an HRV should never pull exhaust air from the laundry room as it will create negative pressure

In Mechanicals | Asked By Troy Stevenson | May 10 13
0 Answers

Audit Report Software

I'm looking for advise on residential audit report software. I had used "Recurve" software until they discontinued their service. I am looking for something with similar features in the long run that would be compatible with BPI and Calif. incentive programs (i.e Title 24, CEC requirments, etc.) but any program that produces a thorough, professional report to hand to clients is also of interest. Any suggestions?

In Project management | Asked By Shawn Ellsworth | May 10 13
2 Answers

Termites & presssure treated wood

I am of the opinion, down here in New Orleans, that Formosan termites will go for pressure treated wood as they would any other. I used to see lumber that was treated with Borate, which they don't seem to like? I don't seem to be able to find it anymore. What's the skinny on this?

In General questions | Asked By roger steinbrink | May 9 13
6 Answers

What to do with SIP face exposed below siding?

We are building our first SIP house complete with SIP foundation. We will be using Hardiplank siding which requires 6" clearance between the lowest plank and grade.

So for those 6" or so the skin of the panels will be exposed, and in certain areas it may not be the foundation panels which will have the pressure treated plywood, etc.

So this general question is: What should I do with that space? Normally this space is just exposed poured concrete walls, but with a SIP building, what do you do?

In Green building techniques | Asked By Joe Hartwig | May 7 13
3 Answers

Optimizing use of rigid foam for top plate/soffit?

I want to blow cellulose in my attic, but it is impossible to get a very good r-value in the tight space where the roof slopes down to the soffit.

In Energy efficiency and durability | Asked By Nick Welch | May 9 13
11 Answers

Should I put poly behind tongue-and-groove paneling on exterior walls?

Location is in NE Ohio. 2x4 wall construction, fiberglass insulation, OSB and 3/4" polyiso exterior foam and finally housewrap. Some AC for one to two months a year.

In General questions | Asked By Richard Hummel | May 2 13
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