Jack Rafters Angles On A Hip Roof

On a hip roof framing plan the lines that indicate the hip rafters ec ac kg and ig in figure 18 3 form 45 angles with the edges of the building.

Jack rafters angles on a hip roof.

What are jack rafters. I use it with an adjustable stanley quick square and can cut the whole roof on the ground take all the timbers up and assemble the lot in one go. If the hip is not backed this is the amount to lower the seatcut of the hip to have the corner edge of the hip plane in with the sheathing common rafter ll major side majll majspan majllratio. At the birdsmouth i supplied the 3 inch seat and for the rafter tail a 12 inch overhang with a 2 inch high subfascia plumb cut which dictated the level cut at the heel.

Drawings of the complete hipped framing system from different angles. Jack rafter plumb line shiftungen. Interactive 3d model of a hip roof for clarity. The two plumb lines on the side of the jack rafter material are always parallel and they are drawn at the thickness of the jack rafter material.

Select the following information by using the drop downs to enter values in feet and inches. The hip roof framing calculator returns the value of the main rafter the side rafter the length of the hip the height of the knee wall and the lengths of the jack rafters. The hip roof layout diagram hip jack common and king common rafters positions. This method is only for equal pitched roofs with an eave angle of 90.

Jack rafters are sloping beams that are progressively shorter in length and support the weight of a roof. You can see from the plan that the total run of a hip rafter is the hypotenuseof a right triangle. After they re up you can snap a line to mark and trim the tails in a nice straight line to make up for any ridge warp or marking cutting and fixing errors. Hip backing angle 15 4 for a good straight fascia add an extra inch or 2 to the tails of all your rafters total length.

All the complicated trigonometry calculations are done for you and there s loads more in there too like diminishing jack measurements and hip rafter lengths and angles as well.