Obviously, the results will be more accurate if you can measure directly.
Here, you can see how each of the five inputs above were figured: Once all of these inputs have been entered into the calculator, you will see that the appropriate rafter width is 120.33 inches. Roof rise – This should be calculated from the base of the roof to the highest point of the roof gable (the peak). This is a heavy roof, so the 1200 mm column on the right side of the table is excluded – it only applies to light roofs.
(In our example showing a 13’x19′ Big Kahuna attached pergola, this calculation would be: 11’6″+ 1’6″= 13′ = Rafter Length of 13 feet). The layout of your home or building will have a significant impact on the final design and slope of your roof. In addition, using the “Rafters” diagram, you can see the precise dimensions of the roof rafter (including length) from every possible angle. Using this handy online tool, you will have an easy way to determine and figure out the specific rafters needed for the unique slope and dimensions of your roof. Once you know the appropriate lengths, you will be able to determine the total cost of your roof project. Choose rafter spacing from Table 10.1 – the options are 480, 600 or 900 mm. Here, the number is 941.86 inches. Here, the wall thickness is 240.57 inches. Here, the birdsmouth plumb is 76.37 inches. Ok. … You can either get these measurements directly, by going up on your roof, or indirectly, by using your house footprint as a proxy for the variables. So for a pergola that is 20 feet wide, you would convert that number to inches–in this case that comes out to 240 inches–then divide it by 16 to get the total number of rafters needed. Span Calculator for Wood Joists and Rafters also available for the Android OS. The actual indentation or cut is known as the “birdsmouth,” while the birdsmouth plumb is the depth of the cut out. Once all of these inputs have been entered into the calculator, you will see that the appropriate rafter width is 120.33 inches. Here, the number is 1166.66 inches. Calculating rafter length starts with a few basic inputs that you will need to gather before using this tool. Birdsmouth plumb – If you study the diagram carefully, you will see that there is an indentation in the roof rafter where it meets the exterior wall of the building. So we increased the size of the Pergola to 18' x 18' with the 12 spoke rafters. eval(ez_write_tag([[300,250],'myrooff_com-large-leaderboard-2','ezslot_10',122,'0','0']));The good news is that there are some common inputs that can be used for any roof, no matter its dimensions, angle, or shape.
Rafter run outer wall – This should be measured starting from the center of the roof span, and then extending to the very edge of the exterior wall. These are the inputs that you will need (all of them measured in inches): eval(ez_write_tag([[300,250],'myrooff_com-leader-1','ezslot_11',123,'0','0']));By entering these inputs into the rafter length calculator, you will get a final number, which is the rafter size. Conclusions about the roof rafter length calculator. also available for the Android OS. Here, the overhang is 320.13 inches. eval(ez_write_tag([[300,250],'myrooff_com-banner-1','ezslot_5',121,'0','0']));Inputs for rafter length calculator. 3” x 10” Rafters . And by getting the prices of wood from your local home improvement store, you will know the exact cost of your roof project. Using this number, you will know exactly how much timber you will need. If you are making repairs to your roof or installing a completely new roof, you will need a rafter calculator to help you figure out rafter lengths. In this case, that number is 15. 4” x 12” Beams . Overhang – The overhang should be measured from the outer edge of the exterior wall to the furthest point of the rafter. In addition, using the “Rafters” diagram, you can see the precise dimensions of the roof rafter (including length) from every possible angle. Wall thickness – It is important to take into account the overall thickness of the exterior wall. Here, the wall thickness is 240.57 inches. 3” x 8” Knee Braces . Here are the sizes we plan to use to hopefully prevent sagging: 8” x 8” Posts . 2” x 6” Shade Planks . Light Polycarbonate roofing . To calculate your Rafter Length for an attached pergola, it is Measurement A + 1’6″. Example of figuring rafter lengtheval(ez_write_tag([[300,250],'myrooff_com-large-mobile-banner-1','ezslot_13',124,'0','0'])); For first-time homeowners, some of these roof inputs might not be immediately obvious, so let’s work through a hypothetical example based on the “General View” diagram. Take note of this measurement, as this will be the first number in the size pergola you choose. Beam size for long span on pergola decks fencing contractor talk what is max distance between posts using 2x12x20 foot beams for a pergola beam span calculator pergolainstructions key 5413352419 pergola beam span calculator pergolaforcarport span tables for 8 x12 x24 western red cedar this pergola measuring pergola dimensions learn the standard.