On Sun, 13 Sep 2009 18:12:33 +0100, a certain chimpanzee, "David WE
Roberts" randomly hit the keyboard and produced:

I expect to use reasonable depth rafters so I can get some insulation up
between them. I am limited on total height by the current regulations - at
least by the dimensions I have to meet if I don't require buildings
regulations approval.

Are you in England or Wales, or Scotland (or NI, IoM, or the CI)? If
E&W, then you may be confusing Planning and Building Regulations.
B/Regs don't care about the height; you can build a shed as tall as
Canary Wharf, but provided it's a single storey building with a floor
area of no more than 30m^2 and no sleeping accommodation, it's exempt.
--
Hugo Nebula
"If no-one on the internet wants a piece of this,
just how far from the pack have you strayed?"