Built up wall

[Jim_Mc_Dade]

Hello,  I have been following the discussions about using the built up roof insulation system(wrap and strap) I have a few questions regarding using the same type of construction to be used on a wall system.  If using T&G 2x material, followed by the blue board sheet insulation (2-2", 1-1" layer), then straping(furing strips), then siding(cedar board&batten), all supported by the sill, protected by a porch overhang roof.
    1)  Is this system possible in relation to the building code?
    2)  If possible, what would be a reasonable span between posts?
    3)  Is the norm to stagger and tape all insulation seams?   
Thanks Jim Mc Dade.   

[Alexis]

The only thing that bothers me with this technique is the fact that sobon, in his book, says that if you want to put 3" or more of insulation, you should put 2X stock on it's edge.

If Jack Sobon says to do that, it's because it's necessary, if it would be strong the other way, he wouldn't say to do that!

Alexis

[TW]

The reason for why the 2x.. always should be put on their edge in a wall.
-When there is a horizontal load on the wall the studs actually get bending stress like a beam. Then beam depth is an advantage.
-When there is vertical load on a wall buckling becomes an important factor. The boards or fiberboard or plywood or gypsum board or whatever sheathing on the inside and outside of the wall prevents the studs from buckling along the wall, which otherwise is the weaker direction of the stud and where it would naturally buckle if left on it's own. Then the only possible direction of buckling is penpendicular to the wall. Buckling is counteracted by stiffness in bending. Now we are back to the advantages of beam depth.

[shinnlinger]

Price it out,

My research shows it will be significantly less $$$ to build a wide stud wall (I saw a guy in Oregon rip a 2x6 in half and space it to 8" or 10" with strapping) and do dense pack insulation vs foam panels.  SIPS will be even more, alot more.

You can obvoiusly "go wide" in a a variety of ways (Like TGI's or 2x10's), but reducing thermal breaks is a good idea and 2x6's are cheaper also.

[Jim_Mc_Dade]

The intended purpose of this type of wall is to enclose a self supporting timber frame structure.   Wind load would be the major concern, that was why I was trying to get an idea of how far this type enclosure system could reasonably span between posts. I look at it like a SIP,  but with screws instead of glue to to tie inner 2x t&g to the out layer of strapping/siding, like its done on a roof.  How ever the t&g, insulation, and strapping would all rest on the sill. 
     The idea of trying to use dense packed cellulose insulation is one I didn't think of and is enviromentally friendlier(greener).
     When using an wall enclosure system that is not the norm,(SiPs,etc) is an engineers stamp required before the code guy will let it fly?
     

[shinnlinger]

Jim,

I would say you should talk to you local building department and see.  I currently live in a no zoning town in the "Live free and Die" state and can do whatever I want as long as I am willing to pay taxes on the square footage (yeah, even for a dog house)

BUt I also lived and built in Eugene Oregon, which had the full meal deal when it came to building inspectors.  I found out there, when building on my own place they were very reasonable.  I did need an engineers stamp on a steeple I put on my shop, but every thing else they were fine with "cocktail napkin" sketches.