Build a Gable Roof
The gable roof, also called a saddle roof, is simple to design and inexpensive to build. Its symmetrical shape is attractive, sheds rainwater and snow efficiently, and allows for maximum attic space. It's a good choice in climates that receive snowfall, but may not work as well in areas that are subject to high winds. If you have carpentry skills, you can build a gable roof for a simple rectangular structure, such as a shed.
Steps
- Nail top plates to all the outside walls. The top plates should consist of 2 boards of sufficient width to cover the tops of the walls.
- Measure and cut ceiling joists from 2-by-4 lumber. You will attached these to each pair of rafters so they resist the outward pressure of the rafters on the walls. Install the ceiling joists onto the top plates so they span the structure from one long wall to the other.
- Cut a ridge board form 2-by-6 lumber. The ridge board forms the peak of the roof. It's parallel to, and as long as, the longer walls of the structure.
- Lay planks across the ceiling joists. This gives you something to stand on while you assemble the roof. Later you can move these planks to the outside of the roof.
- Calculate the rise of the gable roof. You want the slope to be between 25 and 45 degrees.
- You can use the Pythagorean Theorem to calculate the roof's slope and length of the rafter boards if you know the distance from the ridge board to the outside wall and the rise of the roof.
- If you don't want to do the math for the rafters, you can buy a copy of The Roof Framer's Bible, which contains tables that will tell you how long they should be.
- Measure and cut the rafter boards from 2-by-4 lumber. The rafters will be attached to the ridge board at intervals of 16 to 24 inches (41 to 61 cm) and sit on top of the walls. The length of the rafters depends on the rise (height) of the roof and how far past the walls you want the rafters to extend.
- Use a miter box or miter saw to cut the rafter boards so you can attach them to the ridge board at the correct angle.
- Create a triangular notch in the rafters at the place where they will rest on the top of the walls.
- Miter the tail end (the end that extends past the wall) so the rafters will come to a point.
- Make a collar tie for each pair of rafters. You will attach this to the rafter boards near the peak of the roof on the inside, stabilizing the rafters. It's not necessary to miter cut the collar ties.
- Assemble the gable roof. Make sure as you do so that the top plates of the walls fit well into the notches in the rafters. To do this best, get a helper and use and temporary braces.
- Nail planks to the rafters so they run parallel to the ridge board.
- Cover the ends of the gable roof with mitered planks. Leave room to install vents so warm air can escape from the roof and help keep the structure cool.
- Roll out tar paper and nail it to the planks. Begin at the bottom and overlap the sheets. Cover the ridge board with an extra sheet.
- Add asphalt shingles and roofing nails. Begin at the bottom and overlap your rows. You also need to offset the rows so the edges of the shingles are centered on the shingles above and below them.
- Finished.
Things You'll Need
- Hammer or nail gun
- Nails
- 2-by-4 lumber
- 2-by-6 lumber
- Wood planks
- Miter box or miter saw
- Measuring tape
- Carpenter's square
- Ladder
- Eye protection
- Tar paper
- Shingles
- Vents
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