need help with roof framing specs

Started by paul s, July 02, 2017, 05:25:08 PM

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paul s

Finally have a small bit of land and can build what i want!!

building is 12' x 24' with 2x4 stud walls on 16" centers so roof span is in 12' direction

for 16 inches on center what size rafters for a 3/12 pitch roof near Charlotte, NC [Boiling Springs] and what for roof sheathing, likely a metal roof..

thanks for your help

Paul

paul s

i am thinking syp 2x8 16 inches on center will 7/16 osb work for sheathing?

Paul


Redoverfarm

It might depend on what the structure is going to be used as.  Insulated or not, living space or storage?

paul s

will be insulated and lived in from time to time or longer

no big zoning herehope to build to look like cute gardenshed

Don_P

Love the Broad River Greenway down there, used to take the dog on walks when we were around there.

If gabled with 2x6 ceiling joists or shed roofed 2x6 would be minimum around there I believe so the 2x8's would be fine structurally. They won't allow much insulation if it is a shed roof.

You do need to get a building permit for this size building, you can call the building dept anonymously and describe what you want to do to confirm.


paul s

Already talked to the town zoning person, stay 10 feet of the lot line and no higher than the house and no single out building over 1200 sf build as many as u like

one county here south of us is no zoning, so build what ever you want

LatinForLiar

Take a look at some rafter span tables, but I think for a span of only 6 feet (.5*12), 2x6 is going to be plenty (especially with a metal roof). Question: why such a low-pitch to your roof? Obviously with a metal roof you can get away with it, but just curious.

For sheathing I would use 1/2" exterior grade plywood. No need for treated or anything fancy. Another option depending on your budget, is to use boards rather than sheathing, and then cover these with insulated wood panels. This would be more aesthetically pleasing.

paul s

the building is 12' wide and the back wall is 8'tall and the front wall is 11' thus the 3/12 pitch

Don_P

This is another way to check spans, these are the folks that make the code tables;
http://awc.org/codes-standards/calculators-software/spancalc

I prefer to use 5/8 osb for roof sheathing, boards are fine as well. Thinner sheathing doesn't give much bite for the screws and I've actually had better luck with osb than plywood if it gets wet during construction. You'll get opinions both ways there.

Do remember zoning is, or can be, different than the building department, I've run into tight enforcement in NC but every office is different.