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2 Answers

What is the best way to build a 2x8 exterior wall and achieve R-40?

I am building a house near Toronto, Ontario. Winters are cold, and we do see our share of -20 or colder weather. Summers have been somewhat hot in last couple of years.
My wall section looks like this right now from exterior to interior.
Stucco>1"rigid foam board (taped seems)>2x8 studs @ 16"OC>2" closed cell spray foam> R24 Batt>6mm poly>drywall.
I am worried about any moisture getting in the wall so that is why I am considering doing 1" rigid foam board from the outside and poly from the inside.
Can anyone tell me if they have done anything similar.

In Energy efficiency and durability | Asked By Slobo Urosevic | Apr 7 15
5 Answers

I am concerned that spray foam, once installed, can become an accelerant in the event of a fire. Have there been any studies?

There was a new mansion built in Houston that had a fire. The house was completely destroyed. Spray foam was used in all the walls. I have not heard nor read anything about spray foam and fire.
Thanks

John

In General questions | Asked By john winkler | Apr 8 15
15 Answers

Pricing per ton for GSHP and air-to-water heat pump

Is there a general rule of thumb for pricing of a GSHP and Air to Water heat pump for a medium sized installation of ~17 tons or 200,000 BTU/hr. $/Ton or $/BUT? What products fit this market segment?

Do you also have a general rule of thumb for an energy retrofit of a home in $/Ton or $/BTU reduced heating demand?

Is there an issue with using a GSHP in a climate where little cooling is required?

In General questions | Asked By Cathleen Dalmeida | Apr 4 15
20 Answers

Roof furring questions

When it comes to furring a roof, are 1x3 or 2x4 furring strips better to use? I assume the latter because they are stronger/wider and give a better grip area to the sheathing above. Spacing should be what: 12" or 16" on center?

My other question is with the sheathing above. I read that plywood is better than OSB although there has been a lot of problems at the lumber yards with plywood cupping. The lumber yard attendants said that the QC on plywood is really bad because it is so rarely used. I assume 5/8" sheathing is ideal for a metal roof?

In Green building techniques | Asked By Peter L | Apr 6 15
3 Answers

Use scrap polyiso for inground gutters?

I have bunch of scrap 1 1/2" fiberglass-faced roofing polyiso left over from basement insulation project. Next large project I will be working on is fixing grading issues around the perimeter of the house, removing all the bushes right next to foundation, and putting down washed p-stone (likely). I have read before on GBA about those inground insulation "skirts", but there XPS or EPS is recommended with EPDM on top. Would it be bad to just use scrap polyiso under EPDM?

In GBA Pro help | Asked By Apollo S | Apr 8 15
13 Answers

R-25 rigid insulated roof deck with cold metal roof above question

Zone 6 remodel in design phase. If anyone has links to similar design pics/blog building a cold/insulated roof it would be much appreciated.
Insulating roof deck to R-25 or greater with combo of reclaimed rigid foam.
I would like to then create a vent space (my question), followed by Plywood, then metal roofing.
What is the best way to create the vent space and how deep does it need to be (roof pitch varies 7 to 9).
is a criss cross pattern of 1x3 screwed to rafters followed by another horizontal to the ridge the best approach?

In GBA Pro help | Asked By Dirk Gently | Apr 3 15
3 Answers

Turning my Zone 5 attic into conditioned space

So have been scouring for iso to do my basement walls and needed only 40 sheets, but Ive come across a guy who has 100 sheets and needs to get rid of them all at a crazy price.
So my question is can I use this 3' iso on the underside of my rafters to bring my attic into a conditioned space.
The attic insulation is already at R60 (R38 batts and the rest blown in cellulose) but I thought if I have all this left over Iso I may as well use it in the roof and give my central air a break.

In Energy efficiency and durability | Asked By Darren Finch | Apr 8 15
32 Answers

I am overwhelmed with the wall cavity options and need advice

After researching for the last few months on this website, buildingscience.com, and PHIUS.org I am just overwhelmed...buy maybe under informed. I am an owner/builder (former construction project manager...mainly responsible for foundation and electric work then) and this will be my second house. Most of the case studies and articles I have read are about homes in climate zones far more extreme than what we typically have in TN.

In Energy efficiency and durability | Asked By Andrew Bennett | Mar 4 15
4 Answers

Double stud wall with timber ceiling

I am designing and building a double-stud wall, single story house on a slab-on-grade foundation with a frost wall. As a dedicated timber framer, I have tried to hold on to some aspect of that approach while acknowledging that it adds cost and complications with air-sealing, etc. I devised a method where the outer wall supports the roof (cathedral) and the inner wall supports the ceiling assembly. My concerns are with the inner wall bearing the load from the floor to the edge of the slab.

In Green building techniques | Asked By Caleb Creaven | Apr 8 15
3 Answers

Insulating radon-mitigated crawlspace floor

I finally have solve the radon problem in my house and sitting pretty with 0.8 average. Also very happy that formerly "unvented yet might as well be", dirty, and damp space is now so clean, I only walk in my socks there.

That all said, walls I am insulating with polyiso (two layers of 1.5"), rim joist I am going to spray with closed cell, when space becomes warm enough. But it leaves the floor uninsulated.

In GBA Pro help | Asked By Apollo S | Apr 8 15
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