Thanks Paul

I think I will eventually be seeing an engineer.The reason I have not yet is,this is a cottage in Quebec and no stamped drawings are required.Also taking red pine from the lot(no grading required)That said ,I want to do things correctly to avoid future problems.The 4x6 rafters spaced 4' is a concern.Your comment about spreading of the 16' middle bay.When you said plate sizes,did you mean-"joint connection plate"?(the wall plate is 8x8)With regards to lateral stiffness.Plywood or osb on top of the ceiling boards?would plywood or osb on top of the 2x8's(over the insulation)be as effecive?This is still in the planning stage so I am open to change to avoid headaches. Maybe a ridge beam is the better way to go?I belive I can eliminate the collar ties when using a ridge beam.

Regards