Working on a 10'x16' cabin design I plan to build this summer. The walls are 10' high. There is 6' loft on one end that is sitting on a double top plate of 2x4x8' walls to support the loft. On the other end there's a 32" storage ledge on top of the 2x4x10' walls.
I want to build cathedral ceilings (no rafter joists) Generally speaking without all of the information of load, environment, etc; Is the loft and the storage ledge enough to hold the walls together? or do I need a ridge beam?
Given that you have less than 8 feet of unsupported wall, I don't believe you need a ridge beam. Many a garage has been built with hand-framed rafters spanning much more than 10 feet with only one or two rafter ties. You should see little to no movement.
One way to add peace of mind, though, would be to use short collar ties or gussets at the peak, even if just through that unsupported area.
By the way, you never really need a ridge board. The sheathing locks the rafters in place. Modern roofs rarely have them.
From the looks of it you will have about 8' of cathedral ceiling beyond the loft and storage. You should add collar ties at least 32" apart through that span as code calls for (at least back in the day, and maybe it still does) or use a ridge beam the whole span, so the ends that are well supported will assist in supporting the span in the middle.
This is if there will be a snow load on the roof. If not, maybe the beam could be eliminated, but gravity will still have a factor in how this all works.
