Saillies De Toit

I thought this might be a good book.


La CHARPENTE en bois de Gilbert Emery ( RELI - 1 avril 2005)

I draw out page 148, .Saillies De Toit.

Roof projections
With regular projection,  = equal overhang

The ground plan is a trapezoidal ground plan with equal overhang. The book does not explain how to calculate the hip offset from the corner of the ground plan. Disappointing!!!
Back to the drawing board to see how to draw or calculate the hip offset for roof eave angles that are not at 90° and have unequal roof slope angles.

This drawing was generated by my Google SketchUp plugin using the Trapezoidal Ground Plan function.

Irregular Hip Rafter Ground Plan With Equal Overhang

It easy to draw out the tetrahedrons at the hip overhang when the roof eave angle is 90°.

It's also, just a simple math equation to find the hip offset from the corner of the fascia line.

Major Pitch Overhang Run / tan(minor plan angle) = Offset Run on fascia line

24 ÷ tan(36.8699) = 32

Here's a drawing with the math for the trapezoidal ground plan with equal overhang to find the hip rafter offset from the corner of the building plate line.