How to Build Rafters on a Roof

A roof frame is composed of rafter boards which support the roof structure. The size and shape of the roof frame is important as it will determine the shape of the final building. There are many different roofing styles, such as, gambrel, hip, shed, valley, and gable. Each roof style has a unique height and slope. The rafters are the main structural members of the roof, extending down from the ridgebeam to the walls. The rafters hold the sheathing in place which is the final protective covering for the roof under the shingles. Cutting and placing the rafters properly is important for a well built roof.

Difficulty: Moderate

Instructions

Things You'll Need:

• 2-by-6 rafter boards Saw horses Circular saw Tape measure Chalk 16-penny nails Hammer Gloves Goggles

1. Lay out your 2-by-6 rafter boards across two saw horses. Measure and cut a pitch angle on one end and a birds mouth on the other. The pitch cut must lie flush with the ridgebeam and the birds mouth will sit wedged on the wall plate.

2. Use a circular saw set at the maximum depth and make all the end cuts the same on each end of each rafter board.

3. Place a mark on the top wall plate 1 1/2-inches from the end. Continue to make marks every 16-inches on center, leaving 1 1/2-inches from the other end. Make your marks on the opposite wall plate as well. This is your rafter layout.

4. Bring the rafter boards up onto the roof. Measure and mark on the ridgebeam 1 1/2-inches from the end and every 16-inches on center. End nail one rafter to the ridgebeam at the first mark using three 16-penny nails. Nail the opposite rafter to the other side of the ridgebeam using four 16-penny nails at angles.

5. Nail the bottom of each rafter board at the bird's mouth onto the wall plate. Use 16-penny nails, two on each side.

6. Continue to nail the rafter boards to the ridgebeam and the wall plate every 16-inches on center. Make sure to check occasionally as you work to make sure the rafters are plumb and level.

Tips & Warnings

• If at all possible, hire a few helpers so one can nail the rafters to the ridgebeam while the other can nail the rafters to the wall plate.
• Wear gloves to protect your hands from sharp power tools and wood splinters. Wear goggles to protect your eyes from flying wood pieces.