## Saturday, November 9, 2013

### Internal Edge of Hip Rafter On Roof Surface

There's quiet a few different ways to draw out the Internal Edge of Hip Rafter On Roof Surface, but hopefully these drawings will make it even simpler to understand. With the Internal Edge of Hip Rafter On Roof Surface dimension you'll be able to develop the miter angles of a rafter on the roof surface, using the folding or draw down technique, at any skewed angle from the plate line.

The Internal Edge of Hip Rafter On Roof Surface dimension is based on the hip rafter backing angle.
Using trigonometry
Internal Edge of Hip Rafter On Roof Surface dimension = Depth of Rafter x tan( Hip Rafter Backing Angle)

Wire frame model of a roof framing kernel with the location of the hip rafter backing angle.

Transparent view of the hip rafter backing triangle in the roof framing kernel.

Here we'll split the roof  framing kernel into two parts at the hip.

Unfold the roof framing kernel.

The basic roof framing kernel unfolded.

The basic roof framing kernel unfolded with the hip rafter backing triangle added.

The basic roof framing kernel with the depth of the profile rafter drawn and the Internal Edge of Hip Rafter On Roof Surface dimension drawn at the end of the hip rafter backing triangle using the depth of the profile rafter.

On the roof surface you'll draw the center line of the hip rafter. Then you'll draw the edge of the hip rafter using the plan view location at the eave line. Then use the  Internal Edge of Hip Rafter On Roof Surface dimension  to draw the next line.

Here we have a purlin rafter that is parallel to the eave line. Mark perpendicular lines at the edge of the hip rafter and the Internal Edge of Hip Rafter On Roof Surface. Then draw the miter angle lines on the sides of the purlin rafter and the back bevel lines on the top and bottom edges of the purlin rafter.

Here we have a jack rafter that is perpendicular to the eave line. Mark perpendicular lines at the edge of the hip rafter and the Internal Edge of Hip Rafter On Roof Surface. Then draw the miter angle lines on the sides of the jack rafter and the back bevel lines on the top and bottom edges of the jack rafter.

Here we have a purlin rafter that is skewed to the eave line. Mark perpendicular lines at the edge of the hip rafter and the Internal Edge of Hip Rafter On Roof Surface. Then draw the miter angle lines on the sides of the skewed purlin rafter and the back bevel lines on the top and bottom edges of the skewed purlin rafter.

Purlin Rafter perpendicular To the Roof Surface Offset/Skewed From Plate Line