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6 Answers

Open Cell Spray Foam---Bubble Repair

I'm building a new 1 1/2 story home in a HH climate (2B). Insulation is ocspf---6" in walls and roof (i.e. semi-conditioned attic).

The insulation is complete, but there are just a few small areas that aren't well done. There are some areas (corners mostly) that have fist-sized holes in the insulation. It appears that there is enough foam to seal to the outside, but not full thickness because of a bubble. The contractor and the manufacturer both advised that I should just fill these up with canned window foam.


In Energy efficiency and durability | Asked By john walls | Mar 16 12
1 Answer

Do you have to mechanically ventilate an attic space used for storage?

Do you have to mechanically ventilate an attic space used for storage when the whole attic is within the thermal envelope? The roof is 10 inch SIP panels (R-60) and all walls are open-cell SPF.

The owners have asked if there is a code issue here. We can't find anything definitive.

In Building Code Questions | Asked By Ann Lathrop | Mar 16 12
4 Answers

In zone 4A, would I be OK to put 1.5" of closed SPF under my roof deck with unfaced R-38 below that?

I have 2x8 rafters, and they are furred down with 2x4's and there is a 1" gap as a thermal break between them. I want to foam the rafters entirely as well as the underside of the roof deck. I would use .5" sheetrock as an air and thermal barrier below the furring and batt insulation. I know code calls for R-15 air-impermeable foam, but with this set-up in southern, coastal Virginia would this be OK?

In Energy efficiency and durability | Asked By Matt Black | Mar 14 12
9 Answers

Site-built SIP panel — What foam to use?

I previously posted a question about the wall section in an addition where the added guest bedroom and bathroom were going to double as storm rooms. But I'll be danged if I can get back to that thread.

Anyway, on the exterior side of the studs, I was going to sheath with 3/4" Advantech subflooring, then add 1-1/2" of foam, then another layer of 3/4" Advantech.

I seem to remember that extruded polystyrene (blue or pink foam) will shrink with age, and, in fact I have observed this in my crawl space.

In Energy efficiency and durability | Asked By Bill Daugherty | Mar 14 12
3 Answers

Slimmest Blown Cellulose Insulation Cavity?

Another question here. Hoping someone from the insulation community can give me an answer.

What is the slimmest insulation cavity that can be blown? Is it possible to blow 1.5" to 1.75" thick cavities? It seems like you could...you would just have to have a hose that was small enough right?

In Energy efficiency and durability | Asked By Spencer Burnfield | Mar 14 12
20 Answers

Abridged Version of Manual J 8th Addition Excel Program & MANY other questions

I am working on trying to do some sort of reliable energy modeling/comparison for a house that I am designing (and for future projects). I was trying to find out a few things: the difference in energy use between a standard 2x6 wall & a double stud wall, good windows & code, Code 2x6 construction/insulation levels & a better insulated shell with good windows (U-value between .20-.24, Floors R-38 to R-42, Whole Wall R-24+- & thermal break, Ceiling R-60). I downloaded a number of programs and they all seemed very tedious, had a tendency to crash, and seemed very difficult to use.

In Energy efficiency and durability | Asked By Spencer Burnfield | Mar 13 12
4 Answers

Are 3x Studs Req'd. @ Panel Edges of 24" O.C. Exterior Sheathed walls?

The structural engineer I use just gave me a call. He was reading the NDS (National Design Standards) and found that 3x studs are required at 24" O.C. framing that is sheathed w/ plywood/osb. I am assuming this is a requirement only at shear walls, but in the Northwest at least just about every exterior wall is used as a sheathed shear wall.

I was wondering if anyone else has run in to this or if engineers/plans examiners have just been ignoring it?

In Building Code Questions | Asked By Spencer Burnfield | Mar 14 12
1 Answer

Vapor barrier and insulation options

seeking input on insulation and vapor barrier options for 84 sq ft shed reconstruction - down to studs - and want to put polyiso in walls and ceiling with spray foam filler - will provide vented eves with wire mesh to prevent bugs - but concerned about moisture as polyiso not good with water - and trying to avoid blue board - some folks say to simply avoid any vapor barrier applications. need any input relevant that is solid, technical advice. thanks

In Energy efficiency and durability | Asked By carol martin | Mar 15 12
2 Answers

When applying 2" rigid foam on exterior walls on new construction, how are the windows secured to the plywood jamb extensions?

Does the rigid insulation on the exterior negate the need for a poly vapor barrier on the inside?

In Green building techniques | Asked By David Lajeunesse | Mar 15 12
3 Answers

New Green Basics page

When we built GBAGreenBuildingAdvisor.com a few years ago, we wanted to produce an information resource for everybody. Something that would help you get from where you are to where you want to be in Green building, remodeling, and design.

We wanted to help all – builders and remodelers, architects and designers, code officials, consumers, product manufacturers – anyone who wanted to take their game to the next level.

In General questions | Asked By Daniel Morrison | Mar 14 12
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