Lean to Shed Rafter Calculator (into a wall)

Calculate the length of lean to shed roof rafters for any common roof pitch when the top of the rafters stop into a wall. It includes the rise and works in feet and inches or metric values.

How to Calculate a Lean to Rafter

The run for a lean to shed rafter ending into a wall should account for the ridge board nailed into the wall where the tops of the rafters rest into. In other words, if there is a 1 1/2″ ridge board nailed into the wall, and the width of the lean to is 96″, then the run will be 94 1/2″ ( 96″ – 1 1/2″ = 94 1/2″). Enter this measurement into the calculator and select a roof pitch and the length of the rafter will automatically returned along with the rise.