1. PATTERN RAFTER

2. Roof plan

3. Information required Pitch of roof = 22.5° Half span of roof = 2150mm
Eaves overhang
Rafter spacing
Thickness – ridge
hip
rafters
= 22.5°
= 2150mm
= 300mm
= 450mm
= 25mm
= 35mm
= 45mm

4. Calculations required
Rise per metre =
rise/m =
True length per metre =
t.l./m =
Set out length of rafter =
set out length =
Tan pitch angle
0.414
1.082
tl/m x half span
2.327m

5. Bevels required 1. Plumb bevel rafter 2. Level bevel rafter 1. Rise 2.
Half span

6. Steel square application
Rise/m ÷ 2
207
1000 ÷ 2
500

7. Pattern rafter
Set out length
Half span

8. Reduction : Common rafter
Ridge
Half thickness of ridge
Half thickness
ridge measured
square to plumb bevel

9. Reduction : Crown end Half rafter thickness Crown end
measured square to
plumb bevel

10. Creeper spacing calculations
Rafter spacing x tl/m
½ mitre thickness hip
½ rafter thickness
= x 1.082
= 0.487 =
= 24.75mm
= 22.5mm

11. Long point: first creepera
Crown
end
Creeper spacing b
487mm a a c b
Half mitre
thickness out
c is long point
first creeper
Half rafter
thickness back

12. Continuous creeper spacing
X tl/m
487mm
487mm
long point
first creeper
487mm
450mm
487mm
450mm
overhang x
tl/m
325mm
450mm
450mm
300mm

13. Mark edge bevel creeper
Summary
Plumb bevel centre line
Set out length and birdsmouth
Reduction common rafter
Reduction crown end
Long point 1st creeper
Continuous creeper reduction
Eaves overhang
Square marks across top
edge and label
Mark edge bevel creeper

14. Produced by : John Friedman jfriedman@tafensw.edu.au