I'm planning to build a thermosiphon panel for passive air cooling on the outside of a 8 1/4 OSB SIP wall.  The draft plan is attached and loosely based on Gary Reysa's project here:

http://www.builditsolar.com/Projects/SpaceHeating/solar_barn_project.htm

As far as structural loading, the panels replace the siding on the SIPS and are supported by 2x8's ~76" OC.  The panels (three sheets of glass) weigh about 150lbs, so for an 8' SIP you've got about 20lbs per vertical linear foot.

The local building inspector is suggesting (so far only a suggestion and not a mandate, but he hasn't approved the specific plan) that the the design needs an engineers stamp.  Apart from the cost and time of getting this it also doesn't seem to be a reasonable request given the loads involved - I'd hate to be the one to set a precedent in this.

The SIP detail books contain descriptions of how to hang kitchen cabinets, which I'm sure are much more than 20lbs/ft.  I also suspect that I don't need a engineers stamp to hang a shelf.  So three bookshelves on the wall, 1 1/2 inch red oak on 72" centers, 20lbs per linear foot for a bookshelf and I'm already way above the weight of the panels.

So now I need some help justifying why his request is unreasonable.  What properties of the panels should I be presenting to him to support my arguments. 

The axial loading of a SIP is over 2000plf, 250lbs for 1.5 inches of the 2x8.  Do I need to be concerned about this?  The load is more accurately spread of 5 1/2" since the 2x8 is supported by 2x4's.

If my reading of the spec book is correct the pullout of deck screws from 7/16 OSB is upwards of 150lbs/screw and a shear of over 100lbs.  So screws on 6" OC would have 2550lbs of pullout and 1700lbs of shear.  Even nails would provide 10x the required pullout and shear.  Is this the limiting force of the panel? Are there other things I should consider? For example, could I delaminate the panel by overloading the OSB?

What other factors should I be armed with to take back in with the design?

Thanks,

Jim
PS Any other suggestions on the panel design would be welcome.

PPS OT Nail trivia - 8D Ring has 156lb pullout of OSB - I've never got one out yet, the head always breaks off.  Spiral nails have less holding power than smooth, which I think is the opposite of dimensional lumber.

That looks like most of the load rests on the existing wall below. Is there somewhere you could through bolt from the interior. Looks pretty cool.

Brawler,

The 2x8 at the bottom is a different problem, but could also use some help. That's not a wall below it, it's 4" of polyiso insulation, the wall is to the left and shown (approximately correctly) with no insulation. So the 2x8 needs some support, probably just some squares of 2x8 underneath like shelf brackets, or 2x4 horizontally over the old roof. Since that's conventional framing, and the official is familiar with it, I can _probably_ find a solution for which he won't require engineering. Its the SIPs that have him more concerned. The building official is not particularly unreasonable. He's a little bureaucratic and caution, and not that familiar with SIPs. He's a former builder, but I don't think that he has any practical experience with SIPs.

Instead of screws into the OSB, I could use screws through the SIPS. They seem to be rated for 600+lbs per screw. It's somewhat more difficult because you have to get them straight and I don't know if they would cause a problem with the drywall. Maybe a couple of these and then screws into the OSB would keep the official happy. I can put together the numbers for the fasteners, but is there something SIP related that he may raise that I need an answer for?