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# PATTERN RAFTER - PowerPoint PPT Presentation

PATTERN RAFTER. Roof plan. Pitch of roof Half span of roof Eaves overhang Rafter spacing Thickness – ridge hip rafters. = 22.5 ° = 2150mm = 300mm = 450mm = 25mm = 35mm = 45mm. Information required. Rise per metre =

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## PowerPoint Slideshow about 'PATTERN RAFTER' - Mercy

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### PATTERN RAFTER

Half span of roof

Eaves overhang

Rafter spacing

Thickness – ridge

hip

rafters

= 22.5°

= 2150mm

= 300mm

= 450mm

= 25mm

= 35mm

= 45mm

Information required

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

Calculations required

• 1. Plumb bevel rafter

• 2. Level bevel rafter

1.

Rise

2.

Half span

207

Rise/m ÷ 2

1000 ÷ 2

500

Set out length

Halfspan

Reduction : Common rafter

Ridge

Half thickness of ridge

Half thickness

ridge measured

square to plumb bevel

Reduction : Crown end

Half rafter thickness

Crown end

Half rafter thickness

measured square to

plumb bevel

½ mitre thickness hip

½ rafter thickness

= 0.450 x 1.082

= 0.487

=

= 24.75mm

= 22.5mm

Creeper spacing calculations

end

a

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

creeper spacing

X tl/m

487mm

487mm

long point

first creeper

487mm

450mm

487mm

450mm

overhang x

tl/m

325mm

450mm

450mm

300mm

• 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