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To calculate a sloped member in ClearCalcs, you need to use user formulas to adjust lengths and support locations by the rise/run or degrees of the given slope. In this way, you can still enter the length of a rafter from the plan drawing and adjust it in ClearCalcs using the simple formulas below. Using Rise/Run The formula for 7:12in rise over run is: 
Member Length * SquareRoot(Rise^2+Run^2)/Run
=5ft * sqrt(7^2+12^2)/12
Sub in the rise required rise and member length Example 1: 5ft beam with rise of 7:12 inches Using Degrees You can also adjust the length of a member based on degree slope: 
Member Length * 1/cos(theta)
=5ft * 1/cos(30deg)
Example 2: 5ft beam with slope of 30 degrees - N.B. You need to specify either ‘deg’ or ‘degree’ units for the degrees so it calculates correctly Using a Slope Factor You can also multiply the plan length by the appropriate slope factor. slope-factor-chart - Roofing Calculator - Estimate your Roofing ...