Shed Roof

a ridge board would provide an easy support for gable rakes and I like overhang all the way around and soffit venting is best. Setting a 14' (select) or so ridge beam is a piece of cake and have it all marked for rafter placement.

What ceiling height are you planning?

Bud

" Not sure how the walls don't bow out over time on those."
That's why I asked your ceiling height.
If you opt for a ridge beam you can go overkill and support all rafters without tying walls together with ceiling joists, just some rafter ties farther up. That would give you more ceiling height.

Bud

Sorry I'm a slow typer

In Ok with a low slope roof and snow load I was thinking of a 2x12 ridge beam . As for 2x4 rafters, NOT. The money saved will not be worth the compromise. I use a lumber yard, except when I want to hand select a small quantity of lumber then I head to the box stores and flip through their stacks. IMO, go with selected 2x6, better lumber and easier to work with. You can even point it out when selling.

With the 2x12 or whatever, when larger than what you need for the gable overhang, just notch it flush to framing and leave a 2x4 extension.

Bud