Rafter spacing recommendation please!

[Lulu-vt]

It's the roof pitch. Rise over run. For every X" of run the roof rises Y". With a 5/12 pitch, for every 1 foot of run (12") it rises 5". It's a much more reasonable pitch to deal with.
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You would use a framing square to set the 5/12 angle on the ridge end and tail end of the rafters.
And you should also cut a birds mouth for them so they are bearing weight evenly over the top plate.

Do you have anyone with carpentry skills that can help you with this?

Also, I did try the 5/12 roof pitch because it’s close to the 19° slide I need for the snow to slide. But it just looked weird. It looked very squat to the whole building. Maybe I’ll try something inbetween for better overhang.

 

[DobieLover]

I could also cut a "birds mouth" into the wood if you think I should have both.

I do both. It makes the structure more secure.

 

[123RedBeard]

Growing up in VT... I'd recommend 16" on center ...

90° is basically 12/12 pitch, 6/12 is more than fine for a metal roof in VT.

I would also cover the rafters with 5/8" or thicker plywood before adding the metal roof.

 

[Lulu-vt]

I would also cut your "birds Mouth" for better bearing on your wall top plate. Your 24" OC hook your tape to the top plate and mark at 23 1/4, 47 1/4, 71 1/4 etc. This insures that your 4x8 Plywood breaks half way on the rafter. As DobieLover said, a 5 pitch is a lot easier to work with, especially when you start roofing, also you can use shorter rafter material. If your rafter material is what you show you will have plenty of soffet space.

OK. Just to clarify in my own words, you're saying it's best if I have a support rafter halfway through my plywood? So if the plywood is 4' wide then have a rafter at each 24" increment?
As far as the roof pitch, we determined that the 12/12 was the pitch that looked best with our build. But...after this post we are dialing it back a bit. I have done measurements for a 7/12 pitch...holy pythagorean theorem!!! I am also cutting in a birds mouth. Thanks for your reply.

 

[5Australorpasaures]

We call it 24" on center because when you layout with the 23 1/4, 47 1/4 etc this will have your 96" (8') breaking half way on your 95 1/4" layout giving you full bearing on your seam

Not to confuse you, if you move your tape from the outside of your top plate and pull your layout from say your 47 1/4 mark you would now mark 24", 48", not the 23 1/4. Do a work up on a scrap or stud, hook your tape pull your 23 1/4, 47 1/4 71 /14. Take your tape to your first mark, measure to the next mark and it will be 24"s. I really hope this gives you some clarity. The idea is never, ever let any wood float between stud, joist or rafters, always break on nailing surface.

 

[5Australorpasaures]

OK. Just to clarify in my own words, you're saying it's best if I have a support rafter halfway through my plywood? So if the plywood is 4' wide then have a rafter at each 24" increment?
As far as the roof pitch, we determined that the 12/12 was the pitch that looked best with our build. But...after this post we are dialing it back a bit. I have done measurements for a 7/12 pitch...holy pythagorean theorem!!! I am also cutting in a birds mouth. Thanks for your reply.

I forgot to mention when laying out say from left to right place your rafter to the right of your mark

 

[DobieLover]

So if the plywood is 4' wide then have a rafter at each 24" increment?

No. You need the roof decking to run long horizontally not vertically. It gives it more strength. It still puts rafter spacing 24"OC. But because the very outer edge will be flush to the face of the first rafter the second rafter is placed 22.25"OC then 24" from there out.
Then when you place the first sheet with the 4' edge flush to the outer face of the end rafter the other 4' end will land in the middle of the 4th rafter.

 

[Lulu-vt]

No. You need the roof decking to run long horizontally not vertically. It gives it more strength. It still puts rafter spacing 24"OC. But because the very outer edge will be flush to the face of the first rafter the second rafter is placed 22.25"OC then 24" from there out.
Then when you place the first sheet with the 4' edge flush to the outer face of the end rafter the other 4' end will land in the middle of the 4th rafter.

Gotcha! Thanks so much.