Shed Roof

A shed roof slopes in one direction only. Easy Rafters is designed to calculate shed roofs that are framed to a ledger board nailed against a vertical wall, not freestanding shed roofs supported by walls at both ends.

It is possible to calculate a birdsmouth near the top of the rafter for a freestanding shed roof by checking the kneewall checkbox and entering a setback for the kneewall that positions the upper birdsmouth in the desired location.

To Calculate a Shed Roof

Select Shed from the Roof Type dropdown list or click on the corresponding button on the toolbar to calculate a shed roof. The preview window displays a dimensioned side view of the shed roof.

Design Tab


Enter or select the slope of the common rafter.

Building Width

Enter the total width of the building.


Enter the horizontal overhang of the roof including the thickness of the fascia board.

Heel Height/Seat Cut

Accept the default heel height and seat cut dimensions calculated by Easy Rafters or override the defaults by locking one or the other and entering the desired measurement.

Kneewall (optional)

Check the chechbox to the right of the kneewall field to enable kneewalls and enter the distance from the outside edge of the wall to the face of the kneewall. The kneewall birdsmouth will use the same heel and seat dimensions as the bottom birdsmouth.

Lumber Sizes

Enter or select the lumber sizes for the common rafter, ledger board and fascia board. If no ledger board is used enter zero for the ridge thickness or select "No Ridge/Purlin" from the dropdown list.

Fascia Type

Select Plumb Cut or Square Cut from the dropdown list.

Drawing Tab


The Common drawing tab displays a dimensioned side view of the Shed Roof common rafter.

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