Easy Rafters from Attention to Detail

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Unequal Span Valley

The Unequal Span Valley option is used to calculate valley rafters for intersecting roofs with equal slopes, but different spans. In this type of valley framing a long valley rafters runs to the ridge of the higher roof and a short valley rafter butts into the long valley rafter at the ridge height of the lower roof. Both roofs must have the same overhang, heel height, and fascia sizes, both wall plates must be at the same height, the valley rafters must be the same lumber size, and the ridge boards must be the same thickness.

A fixed drawing of the intersection of the rafters and ridge boards is displayed in the preview window and dimensioned side and top views of the valley rafters are displayed in the two drawing pages. The top views are not drawn to scale, rather they are meant to illustrate the locations of the measuring lines and the direction and angle of the bevel cuts.


Parts of an Unequal Span Valley

Long Valley Rafter
The long valley rafter extends from the intersection of the wall plates to the ridge of the main roof. It has a single bevel cut at the top to frame against the main ridge and an inward facing double bevel at the tail for the fascia boards.

Short Valley Rafter
The short valley rafter extends from the intersection of the wall plates and butts into the long valley rafter at the height of the lower ridge board. The short valley rafter has a square cut at the peak where it butts into the long rafter and an inward facing double bevel at the tail for the fascia boards. To find the point where the two rafters intersect, line up the short valley rafter on top of the long valley rafter and draw a line on the long valley rafter along the top cut of the short valley rafter.