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5 Answers

Can I combine floor and wall heating in a solar passive house to avoid overheating?

I have consulted many "experts" on highly insulated houses, most of them recommend to use ductless heat pumps to heat the house. But I am a radiant heat addict...
Apparently the problem with radiant floor and passive solar is that when the sun comes out, the southern side of the house is too hot because the concrete slab has heated during the night and is warm and when the sun comes out it can bring it to a much higher temperature.

Asked By Micheline Freyssonnet | May 22 17
3 Answers

How to insulate kneewalls or interior gables?

I have a room with a vaulted ceiling. The interior gable wall obviously extends to the ridge. On the opposite side of the gable wall is a vented attic space with insulation on the attic floor. I would like to insulate this gable wall against the attic.

Asked By Bob Brown | May 21 17
2 Answers

Help with Vapor Barrier - On Grade Engineered Wood

Hello All. Thanks for a great site. I have been reading quite a few Q&A regarding this topic but seems to be still confused. So I appreciate any assistance.

The home is located in the Dallas area (zone 3a I guess) and was built in 2010 with a plastic vapor barrier under the slab. There's also gutters and grading all around.

I'm trying to install engineered wood on the first floor (on grade) and based on the consensus here is to put another vapor barrier on top of the slab as a safety measure in the long run. This is where I get confused.

Asked By Ram777 | May 22 17
8 Answers

Sealing PT sill plate to concrete slab ?

I am a homeowner in the midst of a 2000 sq ft addition. Houston TX, foundation is a concrete slab. Walls (from inside out) are drywall, stick 2*4 framing with open cell foam, OSB, tyvek, air gap, brick veneer.

The builder used pressure treated 2*4s for the sill plate but there is no (capillary) barrier between the concrete and the sill plate. 3.5" of open cell spray foam is going in the exterior walls today.

Asked By Mark McFarlane | May 20 17
8 Answers

Insulating polyiso with EPS in a roof stack

Has anyone tried protecting the R-value of Polyiso by putting it inward of EPS?
We are contemplating insulating a roof deck with an over-deck foam stack.
We are in Zone 5A (Lake Effect, N.E. Ohio) and the idea is to maximize R-value by using "some" Polyiso. In an attempt to maximize the R-value with a 6" foam stack here's what we have come up with. From inward to outward:
1) Rafters
2) Zip System OSB Decking
3) 2" Polyiso (R-6.7)
4) 2" EPS II (R-4.2) - Staggered
5) 2" EPS II (R-4.2) - Staggered
6) Roofing Membrane
7) Furring and metal roofing
Total R-value of 30.

Asked By Dave-OH | May 19 17
5 Answers

Kerf channel and thermal bridge

I am working through a shed roof design for a small shop and I have always liked protruding rafter tails. Obviously, I know these days they have been entirely eliminated due to the thermal bridging.

I will ask one question though and show a couple drawings. What if one were to cut a deep enough channel or kerf (may not be the right term) along the exterior face of the envelope (in my case, a SIP)? And then, if that channel (all the way around BTW) were filled with a foam of some kind.

Asked By John Brown | May 20 17
5 Answers

Ice & Water Shield and closed-cell foam for an unvented roof?

I'm looking to add exterior insulation to a low-slope wood decking (2x6 T&G) roof.

I have come across details that use rigid foam, but the builder would like to use a purlin system to create a cavity for closed cell spray. My question is, if we go that route, would I still want a peel & stick air-barrier applied to exterior of decking and interior of the purlin/spray foam layer if the closed cell will act like an air barrier.

Bonus question, should the eaves be insulated to reduce ice-damming?

Thank in advance.

Asked By B B | May 20 17
3 Answers

Frost-protected slab on a moderate slope

I've been reading through the "Revised Builder’s Guide to Frost Protected Shallow Foundations" (http://cdnassets.hw.net/10/9d/3808b4b94676968c59b8548815f3/revisedfpsfgu...) and notice that they recommend FPSF on "low slope sites." I'm assuming that this would preclude using on a site of about 15% slope, but not sure what is generally thought of as "low slope." Any thoughts on FPSF on a 15% slope (Zone 5A), building is a split level with slab on grade, double stud walls with a concrete foundation wall serving as the uphill wall on the house and garage.

Asked By Ethan T | May 21 17
1 Answer

Heating a "near passive" house?

Hi everyone, I am currently mid way through the design of the home we will soon build. Coming from a traditional carpentry background and this will be our first 'superinsulated' build. We are not going for passive cert. but building with passive methods and ideas.

House is 2 levels, Walkout basement with lots of south facing windows. 2800 sq ft total.

We are in zone 6B in BC Canada, and aiming for wall R40 roof R60, using the dual stud wall method with cellulose insulation.

Planning to heat the house with a wood fired boiler, and having electric as backup for when we are not home.

Asked By user-6850466 | May 20 17
3 Answers

Do we need housewrap?

Building a new home in Hanover NH. Advantech sheathing will be taped. Then 2 1/2 inches of XPS will then be applied and taped. Then firing strips, then Hardy siding.

Initial plan was to place house wrap on outside of of XPS. Our builder says that perhaps house wrap is not necessary, given the tape on sheathing then again on XPS, but he is willing to add it if we prefer.

Is there any advantage to house wrap with this construction method?

Asked By Frank Torti | May 21 17
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