STB said:
Please provide the code section that allows what you refer to as joist/cripples that will typically have a drywall ceiling attached to them to resist the rafters thrust (not sure if drywall can provide resistance), the size, type,quanity, spacing and connection details for your "stiff-back", and what table was used to determine that an approximately 14' Post/brace is an adequate brace.
Let me first admit, I'm playing both sides of the net.
As a Code Official, I completely agree with your statements above. If it's not in The Code, It can't be allowed (prescriptively).
As a Carpenter, I would say wait a sec.
28' square building
12/12 pitch
4 common rafters at 19' 9-9/16 (no ridge needed, drop 3/4" from 2 side commons to sandwich the first 2 mains)
Commons set at 13'-11-1/4" from corner
4 equal hips at 24' 3"
4 left, 4 right of each jack;
17-10
16-0
14-1
12-3
10-4
8-5
6-7
4-8
2-9
((approx.))
Stiff-back at the commons perpendicular to the joist.
Done.
Carpenter: "Now, Mr. Code Official, you want me to put a stiff-back on EVERY rafter?! Even the last (shortest) 4? There's no outward thrust there! The jacks meet at the hips, 1/2 of each pair is tied to the cj. Where's it gonna go?! ..and a triple 2x12 hip!!!!?"
There needs to be some common sense in the Code interpretation. The Code can't outline every situation, nor should we expect an engineered solution every time.
The stick frame methods I learned, were passed down for generations. The homes my great-grandfather built are still standing (they're a bit drafty, and they don't have fire sprinklers...but I digress)
The Code guys (myself included) like to slam the "we've always done it that way" response. But some things work regardless of what the Code says.
Rant over. Happy Independence Day. Independence from tyranny. Thinner Codes are better Codes.
mj