Measure and Calculate Rafter Angles

What happens here

Set up a laser level to establish a precise horizontal line across the entire roof structure. Use a measuring stick (or grade rod) to measure from this laser line down to the top of the outer beam and then to the top of the inner beam. Record these measurements. The difference between these two measurements, after accounting for the 'height above plate' (the desired depth of the birdsmouth cut on the rafter, typically 8 inches for a 2x10), will give you the effective 'rise' of the roof. Measure the horizontal distance (the 'run') between the two main beams. Input the run and adjusted rise into a construction calculator (like Construction Master Pro) to obtain the precise roof 'pitch' in degrees. For this project, a pitch of approximately 6.1 degrees was determined.

Goal: Utilize a laser level and measuring stick to determine the exact height difference between the main beams, then calculate the run, rise, and pitch of the roof to ensure accurate rafter cuts.