rafters

[alcowboy]

Quick question. What is the max allowed spacing between rafters?

[rocking23nf]

2 feet is the norm I believe, not sure if thats also max.

[Don_P]

To answer in the broadest terms, it depends on what they are holding up. I've put them in 8' apart when covered by a heavy timber deck. The trusses on my shop are 10' apart and then have 6x6 purlins across them every 32" horizontally with 1" board sheathing above that. You could build with purlins running across the two gable end walls and have no rafters.

I've also used double the rafter size on twice the spacing before with a 2x6 T&G deck on top. That looks nice. Typically something like 4x10's on 4' centers.

It depends on what you need..?

[John Raabe]

For normal 2x rafters w/ OSB or plywood sheathing the common roof rafter spacing is 2' o/c. - Insulation, drywall, etc are sized for this spacing.

Once you upsize the rafters to beams and the sheathing to decking (usually for an exposed interior) then there are more spacious options.

[soomb]

For normal 2x rafters w/ OSB or plywood sheathing the common roof rafter spacing is 2' o/c. - Insulation, drywall, etc are sized for this spacing.

Once you up size the rafters to beams and the sheathing to decking (usually for an exposed interior) then there are more spacious options.

John, if building a 10 x 10 shed (office) with 2x6 floor joists 16" OC, topped with  3/4 TG Plywood (glued and screwed), and using 2 x 4" wall construction 16"OC, 8' in height with a slight shed roof slope . In AZ where snow load will NEVER be a concern.  Would you feel reasonably OK with 2 x 6 rafters on 16" or 24" centers?

[Bobmarlon]

I don't want to hijack this thread but I also have a rafter question if anyone cares to give there 2 cents.  I Salvaged some 3X8 fir beams from a house we demoed.  I have enough for my covered deck if I go 4 feet on center  could I do this if I used 2X materia as sheathing or if I notched in some 2 X strapping I just really want to use these beams. 

[bayview]

http://www.awc.org/calculators/span/calc/timbercalcstyle.asp

/

[Bobmarlon]

I know about span calculators that calculator Cant Answer my question.

[John Raabe]

Are you trying to use these 3x8s as joists spaced 4' o/c and then asking what you should use as a decking material?

If so, you could use 2x6 T&G for solid decking but it should not be exposed to rain. I would think that the span is too great for standard 2x open decking that is spaced 1/8" to 1/4" for drainage. Can you get 2 1/2" or 3" decking? That would probably work.

Alternatively, you could run 2x4's supported on a ledger @ 16" o/c between the joists and then use standard decking running parallel to your joists.

[Bobmarlon]

thanks john. No I'm going to have a covered deck and use these beams as exposed rafters but wasnt sure what to use as the decking above the rafters underneath my roofing.  this still kind of answered my question.  Instead of using T and G would it be similar if I sheathed over  2X10 or 2X6 with OSB?