Laying Out and Cutting Common Rafters
Traditional cut rafters are still the go-to approach to roof framing in some areas.
Although trusses dominate new construction in most parts of the country, traditional cut rafters are still the go-to approach to roof framing in some areas. They’re also common in remodeling work and in small jobs such as entry-porch roofs. Laying out rafters involves some math, but only for the first one. After it’s been laid out and cut and its fit has been checked, it serves as a pattern for the rest.
The two starting points for any rafter are the roof pitch — that is, the rise and run — and the building width. The run, or horizontal part, is always 12 (except in the case of a hip rafter), but the rise, or vertical part, varies. For example, an 8-in-12 (or 8-pitch) roof angle would rise 8 in. for every 12 in. of run. The second starting point is the building width. Even when you’re working…