Jack Rafters Hip Roof

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

Jack rafters hip roof.

Rick arnold frequent contributor to fine homebuilding and the journal of light construction presenter at jlc live the katz roadshow the remodeling show. Since the jack rafters are at an angle to the hip rafter some compound cutting is required to create their housing into the hip rafter. 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. When you create a hip roof in a timber frame there are different types of rafters used.

The jack rafters in turquoise connect from the plate in red to the hip rafter and are of different lengths depending on where on the slope they are placed. 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. Span for the main rafters measure from outside of wall to outside of wall. Use the hip roof calculator for an easier way to get started.

Depending on the size of the roof most hip roofs will have 4 6 short jack rafters that are spaced out every 20 inches 51 cm between the hip rafters and the king common rafters. They must must be on the same level. Measure the distance between the angled hip rafter and the top of the wall at 20 in 51 cm increments and cut jack rafters to fit. Rafter is called for only when framing a hip roof but a valley rafter is needed on both hip and gable roofs whenever roof planes intersect.

If more are needed then simply start over by entering the last measurement in the longest jack rafter field. A jack rafter is a shortened com mon rafter that may be framed to a hip rafter a valley rafter or both. Know that the basic skeleton for the roof has to be erected before any jack rafters can be installed. 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.

Thus there are hip jack rafters and valley jack rafters. The first step is to enter the length of the longest jack rafter. The hip rafters in purple form the roofline and extend from the plate to the ridge.