Ridge Height Calculator

Deduct half the thickness of the ridge from the span length this is the correct span length. Another way to do it is to take the building width, subtract the ridge thickness and divide that by 2
Depth of rafter is the actual dimension, for a 2 x 10 you would enter 9.25, the ridge depth is entered the same way. Total rise above plate is the height from the top of the plate to the top of the ridge Height from floor to bottom of ridge would be the length of a support under the ridge. Height Above Plate (H.A.P.) is the vertical height of the rafter above the wall top plate

Horizontal Span of Rafter (inches,run)
Unit Rise (inches rise, e.g. 6/12)
Depth of Rafter (inches)
Width of Birdsmouth (inches, horizontal)
Height from Top of Plate to Floor (inches)
Ridge Depth (inches)
Total rise above Plate (inches) =
Height from Floor to Bottom of Ridge (inches) =
H.A.P.,plumb from plate to top of Rafter (inches) =
Plumb Depth of Rafter (inches) =