I have a 1930s semi with a reasonably traditional purlin & rafter hip roof. I am extending it at the side, and have permission to convert the hip to a gable. My understanding is that it should be possible to leave the existing structure intact (it is apparently in excellent condition) and build the extended roof by joining to the existing purlins, but I'm not quite sure of the mechanics. What kind of joint would I need to use to attach my new purlins to the existing ones?
Also, I'm looking at the building control guidance note for this style roof, and there's a statement that reads "if h is greater than 16t provide restraint here at not greater than 2 metre centres." It looks as though this will be needed in my design, but I'm not sure what kind of restraint would satisfy the requirement. Would ceiling joists running between my new gable wall (with appropriate hangers) and the existing wall (probably attached to the existing wall plate with nail plates or similar) be appropriate restraint? Or is it some other kind of restraint it's after?
Also, I'm looking at the building control guidance note for this style roof, and there's a statement that reads "if h is greater than 16t provide restraint here at not greater than 2 metre centres." It looks as though this will be needed in my design, but I'm not sure what kind of restraint would satisfy the requirement. Would ceiling joists running between my new gable wall (with appropriate hangers) and the existing wall (probably attached to the existing wall plate with nail plates or similar) be appropriate restraint? Or is it some other kind of restraint it's after?