Stick Built Roof/Rafter Questions
I am building a new home in South Central Pennsylvania. I am looking at using 2×10’s to stick frame the ceiling joists and roof rafters. 8/12 pitch , horizontal span of 19 ft. (38′ from front to back of house) The ceiling joists are not a problem:I have enough load bearing walls/partitions to support the span of the ceiling joist. My question is specific to the roof rafters: Using 2×10’s 16″ on center, do I need any other means of support for the rafters? Will be using 1/2″ plywood, standard 30 year fiberglass dimensional shingles on the roof.
Thanks, Mike from PA
Replies
Rafter and Joist spans
http://www.awc.org/pdf/STJR_2012.pdf
I don't have a comment on the rafter span other than to say consult the span charts above. What I do want you to also think about is insulation. Will any part of the rafters form an insulated ceiling anywhere in the house? If so you need to not only think about rafters in terms of span but also in terms of depth to get the needed level of insulation in them. I have been the route of ripping down 2x material for furring down rafters to a depth that can handle the needed insulation. Frankly, its a pain in the axe. It obviously carries some level of danger when ripping due to knots and other deficeincies in 2x lumber. More than that, its hard to get a completely parallel surface when you are combining rafters with their own inherent quirks in crowns plus any error in ripping perfectly plus the crown on the ripped down 2x. Lets just say if you do it, let somone else hang and finish the drywall.
If I had it to do over again, I would have gone with deeper I joists rather than 2x which was fine on the span chart.
Just my $.02 worth.
Rafters in a span that large will have a hell of a lot of horizontal thrust. Have you checked to see what would be required to fasten them to the ceiling joists?
And are you sure you can get 2x10s that long?