Going to be framing in a shed dormer. Looking at the existing rafters through the knee wall they are 2×4 that span 11.5 feet horizontally. Definitely undersized. There is no sagging in the roof though and looking at the house it’s likely early 1950’s or older. I’ll be adding rafters at the ridge for the shed dormer and to span that distance with current code will need 2×8. Question with this is how do you meet up the different size rafters at the ridge? Do I add a 2×10 board to the ridge? Will it be alright that the 2×8 rafters height isn’t the same as the 2×4 on the other side of the ridge? The current pitch is 9/12 and will add a 3/12 shed dormer 14 feet wide