How To Figure Cutting The Lenght Of A Roof Rafter

This is the horizontal measurement from the outside of the wall to the inside of the ridge.

How to figure cutting the lenght of a roof rafter.

Use a tape measure to measure the entire width of your building. On a shed roof rafter run is the distance from a ledger on the main building to the outside of an addition wall or porch carrying beam. The next result is the run. This means that for every 1m the rafter travels horizontally the angled length of the roof will be 1 1543m.

Once you located where the mark falls on the 2 x 10 measure the distance and be sure to add 10 for the overhang. Rafter layout and cutting sequence. 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. Using the appropriate roof pitch table in a rafter cutting guide such as 4 12 determine the length of each rafter based on the correlating measurement shown for 7 feet.

The length of the rafter is given from the long point of the ridge cut at the top down along the top edge the board to the same plumb cut on the rafter s notch. We need to adjust the total run 73 inches in our example by subtracting 1 1 2 inches the full thickness of the ledger adjusted run 71 1 2 inches. Includes result for hip valley factor slope factor and the roof slope in degrees. All we do now is use a calculator to multiply 1 610 by the measurement in the book.

Rafter length using angle v r 2cos a rafter length using pitch v r 2 sqrt 1 p 2 where v overhang r roof span p pitch. 1 1543 x 1 610 1 858m. Measure as precisely as possible down to the 1 4 inch 0 64 cm 1 8 inch 0 32 cm or 1 16 inch 0 16 cm. If you add an eaves overhang dimension then the amount the rafter sticks passed the wall will be added to the rafter length.

Cut one end of each 2 x 8 rafter to get the necessary length desired. Calculate the length of a rafter from the roof slope ratio of inches per foot and a building width measurement. The length of rafter per meter of run is 1 1543. Use our online rafter length calculator to quickly compute the length of the shed roof rafter by entering the measurements of overhead length of roof span pitch or angle.

Rise and run means that a 6 12 pitch roof has 6 of rise vertical for each foot of run horizontal.