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-   -   rafter size (http://www.diychatroom.com/f9/rafter-size-75759/)

Kealii 07-09-2010 10:40 AM

rafter size
 
I'm planning to do a stick built roof on a room span of 38 feet, so the run is actually down to 19 feet. Will have a 5/12 pitch. There will be an interior wall perpendicular to the rafters and a couple walls parralell breaking up the length of the room. Would a 2x8 rafter satisfy this span? This will be built in Virginia.

Scuba_Dave 07-09-2010 11:37 AM

Depending upon the species of wood, grade etc a 2x8 will span around 16' w/16" OC
A 2x10 would be a better choice
Not sure on the snow load where you are
I went with 2x12's for a similar span here

Are you using fiberglass insulation or spray foam ?

Kealii 07-09-2010 07:31 PM

Thank you for the info. The live load is 10psf. Also, to further clarify, this is also an attic space so the insulation won't be in the rafters, but as an fyi it will be R38.

Rory Read 07-09-2010 08:09 PM

Span Calculator
 
FYI, the American Wood Council ( http://www.awc.org/ ) has a span calculator on their website.

You play around with different spacing, loads and species: http://www.awc.org/calculators/span/...rcalcstyle.asp

Gary in WA 07-11-2010 05:58 PM

"Thank you for the info. The live load is 10psf. Also, to further clarify, this is also an attic space so the insulation won't be in the rafters, but as an fyi it will be R38." ------ 10 psf---- on what, exactly? R-38 ---- in the ceiling joists? And a bearing wall carrying the centers, or off to one side? Type of roofing material? Need more info........

Be safe, Gary


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