Jack Rafters Angles On A Hip Roof

This method is only for equal pitched roofs with an eave angle of 90.

Jack rafters angles on a hip roof.

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. 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. Interactive 3d model of a hip roof for clarity. 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.

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. The hip roof layout diagram hip jack common and king common rafters positions. 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. Drawings of the complete hipped framing system from different angles.

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. 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. What are jack rafters. 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. If you were cutting 3 5 x 5 5 jack rafters then the 2 plumb lines would be 3 5 apart. This calculator will help you estimate hip roof parameters including rafters and roof area person outline anton schedule 2011 08 29 17 53 20 one of users asked us to create calculator which will help him estimate hip roof parameters like rafter s lengths roof rise and roof area. Jack rafters are sloping beams that are progressively shorter in length and support the weight of a roof.

Select the following information by using the drop downs to enter values in feet and inches.