VALLEY RAFTER THEORY AND LAYOUT

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Presentation 28

• VALLEY RAFTER THEORY AND LAYOUT

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Valley Rafters

• Valleys are similar to hip rafters

• Run is 45 with the building line.

• Unit run is 16.97?.

• Shortening due to the ridge is typically 1 1/16?.

• Side cut angles.

• Differences to hip rafters

• Seat cut line is not dropped.

• Seat cut plumb line is deeper.

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Valley Rafter Layout Lines

• These lines are added one line at a time.

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Valley Layout for Ridge

• Draw ridge plumb line.

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Valley Layout for Ridge

• Rafter must be shortened for the ridge.

Usually 1 1/16?

• Shortening ½ the diagonal thickness of ridge.

• Draw a square line on the top with a center mark.

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Valley Layout for Ridge

• Side cuts are added for fit.

• Side cut ½ the thickness of valley.

Usually 1 1/16?
Usually 3/4?

• Draw angled line over the top.

• Red lines are cut lines.

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Valley Rafter Length

• Unit Length x Run Rafter Length

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Hip Rafter Length

• If the building span is 24', then the run is
  _____.

12

• If the unit rise is 6?, the hip unit length is
  ______.

18?

• The hip rafter line length is

12 units of run x 18? 216?
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Valley Rafter Length
216?

• Rafter Length

• Measured from first ridge plumb line.

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Birds Mouth Layout
216?

• Draw heel plumb line.

• Measure down equal to common rafter birds mouth
  height.

• Draw seat cut line.

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Birds Mouth Layout

• Measure back ½ valley thickness.

• Draw a plumb line.

Usually 3/4?

• Extend the seat cut line.

• Red lines are the cut lines.

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Valley Tail Layout

• Determine the location of valley fascia plumb
  line.

• Measure either projection or overhang length.

• Measure down fascia plumb distance same as for
  the common.

• Draw a level line.

• Square over the top with a center mark.

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Valley Tail Layout

• Measure back from plumb line ½ valley thickness.

• Draw another plumb line.

• Draw angled lines on top

Usually 3/4?

• Red lines are cut lines.

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Conclusion

• Valley layout lines are added one at a time.