Roof Conversion - Cathedral Ceiling

[frslam]

Hi folks, first time poster here. I've been reading posts on this site for years, it's excellent. From the Isle of Skye. I am currently renovating a house, full strip back-to-block, floor void filled with 75tn of type 1 in preparation for a 100mm slab, PIR and UFH. I'm currently working on the Roof and structure, getting ready to install 6 inch kit panels between gable and half way along the length of the house to support a glulam ridge beam. The ridge beam will support 8 x 2 rafters in between the original 5 x 2 rafters. This is so half the house can have a cathedral ceiling (approximately 6m from floor to ridge). I have a SE who specified the structure but I'm trying to decide which is best way to seat the rafters on the wall head. This is because of how the original roof was built. The original rafter ties extended outside the walls of the house, with a plate running the length of the house, similar to how a ridge board works. The rafters themselves then sit on top of the plate and are fixed through to the rafter ties (ceiling ties) and the ends of this make up the fascia/soffit. This arrangement creates a little more height for the 1st floor rooms, but the difficulty is new 8 x 2 rafters won't sit on the wall head. Has anyone ever seen a detail where timber is cut (triangles) and glued/nailed or screwed to bottom of rafters to widen the seat to allow rafters to sit on the wall head? Hopefully this is maybe easier to understand on my wee sketch.

[JohnMo]

Your structural engineer should tell what you have to do. Not sure it's down what you or I feel is correct. Your wind loadings are huge, call or email the structural engineer.