COMMON RAFTER LAYOUT USING THE CALCULATOR METHOD

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Presentation 24

• COMMON RAFTER LAYOUT USING THE CALCULATOR METHOD

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Procedure Overview

• Calculate the length of the rafter.
• Calculate the length of the rafter tail.
• Lay out the rafter.
• Cut the first one and use it as a pattern.
• Cut the remaining rafters.

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Rafter Length Calculation

• Needed information is found on the set of plans.
• Example If the unit rise is 6?, the building
  span is 22', and the projection is 16?, what is
  the rafter length?

6?
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Rafter Length Calculation

• Rafter Length Run x Unit Length.

11 x 13.42? 147.62? 147 5/8?

• Projection 16 12 x 13.42? 17.89? 17 7/8?

13.42?
6?
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Rafter Layout Step 1

• First, crown the board.

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Rafter Layout Step 2

• Draw plumb line for the ridge.

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Rafter Layout Step 3

• Shorten to allow for the ridge and draw another
  plumb line.

Usually ¾?
Measured perpendicular to plumb line.
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Rafter Layout Step 4

• Measure rafter length from original line

Mark plumb line
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Rafter Layout Step 5
Measure tail length from birds mouth plumb line.
Mark another plumb line.
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Rafter Layout Step 6
Mark level lines.
Size depends on fascia
2 - 4? Typical
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Last Step

• Check crown
• Check calculations
• Check measurements
• Cut rafter as a pattern
• Use pattern to lay out remaining rafters

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Conclusions