stryped fired this volley in news:80401bcf-e992-
:

Also, instead of purchasing trusses, could I just make a 2x4 ridge
board and run 2x4 rafters down from that?

Forgot to answer that part:

You can, but you need collar ties between the rim beams to hold the ridge
up (think "ceiling rafters"). Remember that a ridge board doesn't hold
_anything_ up unless it's on center-posts, it is _held_up_ by the
rafters, which, if allowed to spread at the walls, will sag. Ridge
boards are just convenient nailing surfaces for the rafter tops, and a
way to longitudinally brace the rafters at the same time.

For that small a job, I'd be tempted to make up my own trusses with
gusset-glue-n-nail. They're not code anywhere anymore, but simple to
make, and plenty strong enough for a simple pole barn.

By the time you get a ridge board and all those collar ties in place,
you'd have spent more than for trusses.

LLoyd