Claw Lines for Plumb Hip Rafters
The claw lines are laid out on the roof surface.
Seat Lines that develop the claw lines
- Purlin Rafter Seat Line Dimension for Plan View
- Purlin Rafter Seat Line Dimension for Roof Surface
- Hip Rafter Seat Line Dimension for Roof Surface
- Hip Rafter Dimension for Claw Line #1
- Hip Rafter Dimension for Claw Line #2
- Hip Rafter Dimension for Claw Line #3
- Hip Rafter Dimension for Claw Line #4
- Hip Rafter Dimension for Claw Line #5
The hip roof claw lines are based on the Main and Adjacent side roof slope angles. These claw line dimensions will only work on hip rafters that are backed out and offset to have equal shoulder heights at the eave line. The claw lines allow you to check your geometric roof surface layout or use these claw line dimensions to layout the claw lines on the roof surface independently of the the other parts of the roof to cut the upper and lower claw angles on jack rafters, purlin rafters and skewed purlin rafters.
The claw lines are based on the
- Profile Rafter Depth
- Hip Rafter Depth
- Hip Rafter Width
The profile rafter depth depth should be the same size as the hip rafter depth if your rafter has an lower claw. Use the claw line dimensions for the correct side of the roof if your roof has two different roof slopes.
Claw Line Dimensions
- Claw Line #1 represents the center line of the hip rafter. It is always equal to 0.
- Claw Line #2 represents the edge of the backed out hip rafter.
- Claw Line #3 represents the internal edge of the hip rafter backing triangle. It is the intersection of the edge of the hip rafter and the bottom of the rafter. Use lines 2 & 3 for the development of the miter angle on the side of the rafter.
- Claw Line #4 represents the intersection of the bottom side of the rafter with the hip rafter.
- Claw Line #5 represents the intersection of the top side of the rafter with the hip rafter.
- Use lines 4 and 5 to develop the lower claw line on the side of the rafter.
If you use the claw lines independently of the roof, use the Sheathing Angle to draw out the correct roof surface. To draw out the roof surface you can enter the eave length, like 24" in a calculator and use the roof Sheathing Angles as the roof slope angle to calculate the length of the common rafter length on the roof surface.
Roof Sheathing Angle Example:
- Rafter Length on Roof Surface = tan(Roof Sheathing Angle) × Eave Length
- Eave Length = 24"
- Roof Sheathing Angle = 58.84094°
- Rafter Length on Roof Surface = tan(58.84094°) × 24 = 39.69269" or 3 11/16"
Once you have the claw lines laid out you can place a jack rafter, purlin rafter or skewed purlin rafter on the claw lines to draw out the miter angle and claw angle on the sides of the rafter. The Roof Sheathing angle is also transferred to the top and bottom edges of the rafter for the correct back bevel on the rafter.