Framed my first hip roof in 2008. Cut three hip rafters wrong before getting one right. Nobody tells you how different the angles are from a simple gable.
Why Hip Roofs
All four sides slope down to the walls. More stable in high winds than gables. Hurricane zones favor them for good reason. Also looks more finished from any angle.
Trade-off is complexity. More cuts, more math, more ways to mess up. Worth it for the right house.
The Parts You Need to Know
Ridge board runs along the peak, shorter than on a gable roof. Common rafters slope from ridge to walls like normal.
Hip rafters are the tricky ones. They run diagonally from the corners up to the ridge. Different angle, different length calculation, compound cuts at both ends.
Jack rafters fill in the triangular sections. They connect the hip rafters to the ridge or to the wall plates. Shorter as they get closer to the corners.
Tools for the Job
- Framing square – essential for laying out cuts
- Speed square – faster for marking common rafters
- Circular saw – make sure the blade is sharp
- Tape measure – buy a good one
- Calculator – phone works, dedicated construction calculator is better
- Level – the longer the better for checking alignment
Calculating the Cuts
Common rafters use basic rise and run. Pitch tells you the angle. A 6/12 pitch rises 6 inches for every 12 inches of run. Framing square makes layout straightforward.
Hip rafters run diagonally, so they’re longer for the same vertical rise. Use 17 instead of 12 as your unit run. The math works out because of the diagonal.
Construction calculators handle this automatically. Worth learning to do it manually though. Calculators break.
Cutting Tips
Common rafters get a plumb cut at the ridge and a bird’s mouth where they sit on the wall. Tail cut depends on your overhang design.
Hip rafters need compound cuts – angled in two planes. This is where people mess up. Cut a test piece from scrap before cutting your actual lumber.
Jack rafters get progressively shorter. Calculate the difference between each one and they go fast.
Assembly Sequence
Set the ridge board first, braced solidly. Install opposing common rafters to hold it in position.
Add more commons until you’re near the corners. Then the hip rafters go in. These lock everything together.
Fill in the jacks last. Check for level and plumb as you go. Fixing alignment problems gets harder as you add more pieces.
Sheathing
Plywood or OSB goes on perpendicular to the rafters. Start at one bottom corner and work your way up and across.
Stagger the joints. Leave small gaps between panels for expansion. Nail schedule matters for code compliance and for actual performance in storms.
Lessons Learned
Take your time on calculations. Rushing creates waste and frustration. Check alignment constantly during assembly. And accept that the first hip roof takes longer than you think it will. The second one goes faster.
Leave a Reply