Ceiling not bearing on exterior walls 1

[bill4sp]

Can anyone help me with this ?
I have a project to continue an area with an addition to follow existing roof, ceiling, interior and exterior walls. I am questioning the location of the ceiling joists. a semi arched effect is existing. Ceiling height in livable area is 9'4" Exterior top plate is 8'2".
The ceiling joists are lagged to the rafters a foot above and two feet back from the exterior wall. The other end is supported by an interior load bearing wall (2x6,16 oc with 2x10 16 oc, 2nd floor floor system(band board))span is 11'4". In checking the allowable rafter size it is 2x8 (13.4 wall to ridge horizonal, 6:12 pitch).Is the fact that the rafters are over sized making this ceiling joist acceptable??

 

[SlideRuleEra]

You will have to "run the numbers" to be sure. I would consider the tributary load from each ceiling joist to be a point load at the location where it is attached to the rafter. This point load would be in addtion to all the other roof load cases that must be considered. Since the point load is near the end of a rafter, be sure to check shear in the rafter in addtion to moment & deflection.

As always, take a good look to make sure connections are adequate.