The results are automatically generated for 16 rafters. It is traditional for most farming carpenters to use inches only on jack rafters anyway. It simply slowed the calculator down too much to generate feet and inches. The next 16 are the lengths of the jack rafters in inches and fractions. Jack rafter (Arch) in England, one of the shorter rafters used in constructing a hip or valley roof in the United States, any secondary roof timber. If you are not familiar with these methods, then you may be better off to leave the bevel alone and just cut the rafter square. Anything over that presents several options for making the cuts fit proper into the hip or valley. Most modern saws will adjust up to a 55º. If the pitches are different, then the bevels will be different. As long as the roof pitches are the same, then the bevel will always be 45º. This is the angle in degrees to set the circular saw you should be using to cut the rafters. The first one is the bevel of jack rafter. Knowing this, 17 results are automatically generated below. Just remember if it is different, then the measurements of the rafters will be different and will have to be handled by repeating the steps for this side. If it is not the same it does not matter to this calculator. Most of the times it is the same as the pitch the jack rafter is on. This is the adjacent roof that will share the hip or valley. It is also necessary to select the pitch of the complimentary roof. Next select a the pitch the jack rafter is on. The words at the top of the list are the ones most associated with jack rafter, and as you go down the relatedness becomes more slight. The top 4 are: beam, structural member, eave and wood.You can get the definition(s) of a word in the list below by tapping the question-mark icon next to it. It can be slightly faster to enter “311.5” in the inches box besides entering “25” in the feet box, “11” in the inches box, and selecting “1/2” in the fraction drop down. Below is a list of jack rafter words - that is, words related to jack rafter. The inches field will accept decimal values for those familiar with decimal values. You can use all three fields, the inches and fraction, or the inches fields. Another technique is to locate the first jack rafter in from the corner of the. The top of this calculator has three fields labeled “Feet”, “Inches”, and “Fraction”. The common difference is subtracted from the length of the common rafter. The first step is to enter the length of the longest jack rafter. Use the hip roof calculator for an easier way to get started. Know that the basic skeleton for the roof has to be erected before any jack rafters can be installed. If more are needed, then simply start over by entering the last measurement in the longest jack rafter field. This calculator returns the first 16 jack rafters. The only method that is 100% foolproof to find the values for all jack rafters, no matter what the pitch or even if they are on different pitches is to physically measure the long rafter and the short rafter and then divide the difference by the number of spaces. Jack rafters are sloping beams that are progressively shorter in length and support the weight of a roof.