Common Rafter Joint

I'm building a 24'x30' "tall posted cap" timber frame workshop utilizing 5"x8"x15' common rafters 30" on center, ending on outer 8"x10"x30' top plates and meeting on a 8"x10"x30' ridge beam (slope is 9/12 and material is EWP). I have two
questions: 1) Should I notch rafters to meet the ridge beam or should I notch the ridge beam to accept the rafters. 2)What joint should I use where the opposing rafters meet ex: butt joint with a metal strap nailed on top of rafters; half lap and pegged: tounge and fork or ????. Regards, Dennis.

Dennis: If you go to the TFG home page and click on Publications at the top of the page and highlight Joinery and then Historic you'll go to a page where you can download in a PDF file articles written about joints and joinery. If you select Part 5 Roof joinery you'll have a ten page article to review and see all different types and ways to do what you're trying to do. There are many ways to do what you want to do and any of these could be the correct way, it's your choice. Good luck with your research. Jim

Dennis, you might first verify the loading on the ridge, since the ridge will bear more weight than the individual plates. This I believe is critical in a tall posted cape scheme, where simple bearing capacity of the ridge will prevent spreading at the plates and stress at the lower ties. So identically sized plates and ridge may not be appropriate. When you size the ridge, you should consider the reduced cross-section at the joint as the true beam size especially if you are cutting grain on the upper or lower third of the beam where the stress on fiber is greatest.

My choice, for simplicity, is a bearing housing on the upper side of the ridge with a sloped ledge, butted and strapped at peak and birds mouth cut into rafter. I would prefer the half-lap at the peak with pegs that have a knob on one end and kerfed and wedged at the other end.

Dennis --

No excuses or blame here whatever, but, yours is the type of question, which perhaps explains some of the lack of reply in this forum.

Technical enough ( I know the name invites it ) to require a well concidered answer and at the same time, not providing enough information to give you the response you might hope for. In truth, you ask for far more than a few moments of good will could provide, and thats putting liability aside.

You do not say how your bents are configured or what it is you are doing to resolve thrust - a major part of any design and particularly important in a "tall posted cape"

Your doing the right thing.

Keep wondering out loud !