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Discussion Starter #1
I've got your basic rectangle shaped house (40'x 27') with a hip roof. Roof framing is all 2x6. I'm adding on a large addition to the 27' wide end that will make the house essentially L shaped. The new addition roof is higher than the existing roof so I need continue the existing house ridgeline so that it "dives" into the new roof.

A few folks have told me to leave the existing hip roof structure and just overframe the existing roof. The existing roof framing is all sound. The other alternative is to completely remove the hip and jack rafters on that end (basically the last 14 feet of the roof) and just replace with common rafters that match the existing common rafters.

If you were doing this which way would you go.
 

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The old roof hip is a 2x6, but today has to be one size larger than the commons. 24"o.c., IRC says 2x6 will span- 11'9" only, with no snow load. So it should be 2x8= 14'10" span. Plus it has to hold the new over-frame and ridge of new. I would build it to the second choice for certain.Leave the old ceiling joists. Be safe, G
 

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Discussion Starter #4
Thanks Gbar, I think you got me on the hip size. I don't recall noticing the 2x6 jacks sticking down below the hip so I'm betting that I didn't pay enough attention to realize that the hip was a 2x8. I'll have to take a look again.

The rafters are all 16" oc so I just pulled up Table R802.5.1 (3) which should be correct for my situation (30 psf snow, 10 psf dead). Looks like the 2x6s aren't enough unless they happen to be select which I doubt (but will certainly check for). The overframe itself shouldn't put the roof above the 10 psf dead load because I'm planning on removing the old shingles before overframing.
 

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I'm in the process of working up some concepts of that very thing for a friend.

This matches a 10' high addition to a standard 8' height existing house.

If you have SketchUp, I'll send you the file so you can play with it.
 

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