How do I calculate a load on a ridge with common rafters? I want to split the rafter load in half. Half going to the ridge, and half going to the plate. This would say that the ridge must hold twice the load as each of the two plates do. If this was a floor I would say this is true. A senter (or summer) beam would hold twice that of the outer beams suporting the joists. But in the roof (because of the angle)my epereance says the plate caries more of the potetial load. How should I size my ridge? The building in mind is 24' wide with a 9/12 pitch.