How To Figure The Length Of A Roof Rafter

The rise of the rafter.

How to figure the length of a roof rafter.

Allow for ridge thickness when determining rafter run to outer wall. If you add an eaves overhang dimension then the amount the rafter sticks passed the wall will be added to the rafter length. Rise and run means that a 6 12 pitch roof has 6 of rise vertical for each foot of run horizontal. The rafter member will be longer.

Contents1 rafter of roof 2 span of roof 3 rise of roof 4 pitch of roof 5 run of roof 6 exmple 1 7 example 2 8 calculate rafter length using angle. Step 4 add the measurement for the overhang the eaves on the outside wall to the result obtained in the rafter guide to determine the overall rafter length. Note that this is not the actual length of the rafter. See rafter run to outer wall calculator below.

Calculate the length of common rafters with this free and easy online tool by entering a dimension for the roof width selecting a pitch for the roof and the thickness of the ridge. The run of the rafter. 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. While making roofing for your house with the roof rafters it is important to know the rafter length to make the roof seat perfectly on the rafter.

Calculate the length of a rafter from the roof slope ratio of inches per foot and a building width measurement. The length of the rafter. The results are automatically fired. The diagonal measurement is the full length of the rafter minus the overhang.

Given here are the formulae to calculate the length of a shed roof rafter to make your roofings stronger and look beautiful. Half building width minus 1 2 ridge thickness. Print full scale rafter cut templates and birdsmouth templates fold template over rafter to mark or cut through. Pitch is the incline of the roof represented as the ratio of rise to the span twice the run.

For example if the roof rises 4 feet and the span is 16 feet twice the run. Determine the camber along the timbers length before you can mark the rafter lengths and layout check the camber of the timber. It is the length of this portion of the rafter. Hook your tape measure on to the rafter and measure the diagonal rafter length that you calculated earlier.

When the rafter is installed this top long end will be at the peak of the ridge beam. 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. If you plan to have overhang etc. The dotted line is how the rafter length measurement is used measure from the point at the top down the length and plumb a line there.

Height of the scaffold. Before starting the calculation we need to know some technical terms related to a pitched roof.