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5 Answers

Over slab polystyrene foam board insulation and clay tiles

We are using polystyrene board insulation for an over slab application. Is 25 psi polystyrene foam board insulation adequate to support one layer 1/2 inch osb board, one layer of cement backer board topped with ceramic tile?

In Green building techniques | Asked By Tim Hatcher | Mar 14 13
2 Answers

Did I get the right spray foam?

Hi. First thank you to the wonderful people who contribute to this forum. I need some advice and hopefully reassurance that I did the right thing. We just had open cell spray foam installed on the roof deck of the attic, in the eves and dormer roofs of our 100 year old house. I thought I had thoroughly researched this before hand but I guess not because today I found a post here that says this is all wrong. I did ask the spray foam contractor why not use closed cell but he said that open cell was the way to go for this installation. We live in Philadelphia PA which I believe is zone 5.

In Green products and materials | Asked By Cherylann Schieber | Mar 17 13
9 Answers

Daikin or Mitsubishi minisplit?

we have decided on a 12,000 btu ductless mini-split for our superinsulated project. the design temperature is -32c and we have back-up electric resistance heat. anyone have strong preference of one manufacturer over the other?

In General questions | Asked By erik olofsson | Mar 15 13
0 Answers

Manual J app?

Anyone have experience with one of the Manual J iPad apps?

In General questions | Asked By erik olofsson | Mar 17 13
4 Answers

Trying to estimate whole-wall values for retrofit?

I'm in the middle of calculating conductive heat loss within my retrofit design, and having a tough time finding any resources for estimating framing factors using the double stud system. I'm also planning on using TGI rafters, and having similar results in terms of not finding recommended frame factors.

Anyone have any thoughts?


In General questions | Asked By kevin freeman | Mar 16 13
12 Answers


Apologies if this has been covered many many times...

I am building a garage, with rental apartment above, in Rhode Island.
- Climate zone 5 (or 4-Marine? The humidity-controlled bathroom fan seems to run all summer, windows open)
- 24x36, approximately 800 SF of living area, unheated garage area.
- Glazing: Lots on the South (view) side, minimal on E, N, & W. Mid-range manufacturer.
- Framing 24" OC throughout: 2x6 walls, 2x10 (or 12?) floor, complex truss roof.
- Siding 50% wood shingles, 50% cardboard-cement clapboards (matching the "big house")

In General questions | Asked By curtis betts | Mar 12 13
4 Answers

Support for 16 inches of cellulose over dropped ceiling?

We have vapour retarder membrane under the flat part of the roof trusses but want to reinforce that to hold up the 16" cellulose in attic as there will be no drywall there (dropped ceiling). Lath or chicken wire are the only two options that come to mind - any other cost effective and efficient means of providing support to prevent sagging, popping staples and voids?

In Energy efficiency and durability | Asked By Patrick Walshe | Mar 15 13
4 Answers

Interior rigid foam installation

I am remodeling a 1905 Folk Victorian (code for farmhouse). The majority of the house is 2x4, with the exception of an addition which is 2x6. I looked into foam exterior but it would involve removing a lot of original molding and architectural details that add to the house. With spray foam at $7000, it is a $6000 premium over fiberglass. Not worth it. This is where I decided to go with XPS on the interior (or even polyiso).

In Green building techniques | Asked By Ryan W. | Jan 3 13
16 Answers

Maximum Insulation in Thinnest Wall


I live in downtown Toronto (Zone 6), Canada. I'm building a brand new addition to an existing 1888 brick house, on a narrow 17' wide lot. I'm interested in getting the best thermal performance (R40) within the thinnest assembly (11" wide) so here is my idea:

From inside to outside -
5/8" GWB
2x4 wood stud framing with
3.25" of high density spray foam (R21)
1/2" plywood
air barrier
5" Roxul Mineral Wool (R20)
1" wood battens or alternately 6" thermally broken z-girts
metal cladding (I am hoping to use a flat seam metal panel of some sort.)

In GBA Pro help | Asked By Jeanne Ng | Mar 12 13
24 Answers

Reflectix still claiming R4.2 for its bubble wrap - my HVAC guy is hooked

After reading up a bit on this site, I am worried that my HVAC person is installing the wrong product on the metal ductwork that he is now hooking up. As I understand it, Reflectix bubble wrap might have some benefit in a very hot unconditioned attic where the ducts are carrying cold air. But in my case, the opposite is true: the ducts are carrying hot air only and they are located in a cozy spray foamed attic. Mold formation is not an issue here (the basement is a different story, alas).

In Green products and materials | Asked By rich cowen | Mar 25 12
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