PATTERN RAFTER

Roof plan

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

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

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

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

Pattern rafter Set out length Half span

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

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

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

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

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

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

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