PATTERN RAFTER

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PATTERN RAFTER
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Roof plan
3
Information required

• Pitch of roof
• Half span of roof
• Eaves overhang
• Rafter spacing
• Thickness ridge
• hip
• rafters

• 22.5
• 2150mm
• 300mm
• 450mm
• 25mm
• 35mm
• 45mm

4
Calculations required

• Tan pitch angle
• 0.414
• 1.082
• tl/m x half span
• 2.327m

• Rise per metre
• rise/m
• True length per metre
• t.l./m
• Set out length of rafter
• set out length

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Bevels required

• 1. Plumb bevel rafter
• 2. Level bevel rafter

1.
Rise
2.
Half span
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Steel square application
Rise/m 2
207
1000 2
500
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Pattern rafter
Set out length
Half span
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Reduction Common rafter
Ridge
Half thickness of ridge
Half thickness ridge measured square to plumb
bevel
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Reduction Crown end
Half rafter thickness
Crown end
Half rafter thickness measured square to plumb
bevel
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Creeper spacing calculations

• Rafter spacing x tl/m
• ½ mitre thickness hip
• ½ rafter thickness

• 0.450 x 1.082
• 0.487
• 24.75mm
• 22.5mm

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Long point first creeper
c
Creeper spacing
b
487mm
a
a
c
b

• c is long point
• first creeper

• Half mitre
• thickness out

• Half rafter
• thickness back

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

• Set out length and birdsmouth

• Plumb bevel centre line

• Reduction crown end

• Reduction common rafter

• Continuous creeper reduction

• Long point 1st creeper

• Square marks across top
• edge and label

• Eaves overhang

• Mark edge bevel creeper

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Produced by John Friedman
jfriedman_at_tafensw.edu.au