Roof carpentry is the process of building a roof that protects and covers a structure from rain, snow, sunlight, extreme temperatures and winds. It’s a subset of framing, the main structural timberwork that goes into a building frame. It requires detailed calculations and precise cutting and a strong understanding of how to use wood and metal connections.
To build a roof, you first need to determine the rise, span and run of each rafter. You can use a construction calculator to do this quickly and accurately. Then you can start to lay out the rafters. A traditional pitched roof has inclined studs called rafters that meet at the peak and support the load. For wide roof spans extra support is provided by a horizontal cross brace, called a purlin, that connects the rafters together. You might also see a strut, which is a diagonal support between two principal rafters, to prevent them from collapsing inwards.
Once the rafters are cut, you need to install them. If you’re working on a building that’s still a frame, this can be done using ladders or scaffolding. If you’re working on a completed building, it may be easiest to hoist the trusses into place with a crane.
Before you do this, you should install temporary bracing to hold the trusses until the sheathing and permanent bracing are installed. To do this, nail a batten that’s longer than the distance between each rafter to the center of the eaves wall frames. Then nail it to the end of a rafter at one gable wall end and another on each side of the ridge board at the other gable wall end. roof carpentry