Our roof rafter calculator tools are handy for calculating the number of rafters needed, rafter length calculator, lineal feet of rafter, board feed in ridge and sub-facia,and the total board feet in the roof. rise and run means that a 6/12 pitch roof has 6" of rise (vertical) for each foot of run (horizontal).. 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 roof pitch calculator calculates slope, pitch, angle and rafter lengths, based on input of rise (m) and run (r).use the diagrams on this page as a reference when inputting rise and run, and while interpreting the calculated results..
Calculate the length of a rafter from roof pitch and a length measurement. includes result for hip/valley factor, slope factor and the roof angle in degrees if you add an overhang dimension then that would be the amount the rafter sticks passed the wall in the calculation.. The length of the rafter. the rise of the rafter. the run of the rafter. height of the scaffold; rafter calculator instructions. enter the value for the roof width (outside to outside) in feet, inches, and fraction, inches and fraction, or use the inches box to enter a value in decimals if that is your preference.. For larger roofs though, i use a roofing ready reckoner. a ready reckoner is pretty much a 'rafter length calculator' - a book full of tables for working out the rafter lengths quickly and easily. each page has a different table depending on the pitch (angle) of your roof with all the figures you need; there are a few good ready reckoners.
