03
May
Jack Rafter Plumb and Side Cuts. Using the skewable hanger eliminates the need to make an angle cut on the valley jacks.
The first step is to enter the length of the longest jack rafter.
How to cut jack rafters. How to cut in a jack rafter using the ready reckoner book covering edge and plum cuts. Also using pattern to measure. Using a common rafter I mark and cut the ridge birdsmouth and rafter tail to create my jack rafter pattern see illustration above.
Starting at the upper end of the rafter I mark 18 12-inch centers at 18 12 in 37 in 55 12 in and so onalong one edge of the pattern rafter shown on illustration above and in photo bottom right. When you cut the rafters youll need to make 3 separate cuts. The ridge cut also called the plumb cut at the top of the rafter the birdsmouth cut which itself comprises 2 different cuts where.
I was taught to cut jack rafters by laying the amount of jacks on the bench half crowned one way and half crowned the other way. Mark and step off the jack differences on the common pattern Long Point and Short Point. Take the pattern and mark one side of all the jacks to the long point of the plumbcut and then flip the pattern over and mark the.
The side cut angle of a hip jack rafter always changes depending on the pitch of the roof eg 35 degree pitch roof side cut angle of 394 degrees 45 degree pitch roof side cut angle of 352 degrees Its the same with hip or valley side cuts 35 degree pitch roof hip side cut of 418 degrees 45 degree pitch roof hip side cut of 392 degrees. The first step is to enter the length of the longest jack rafter. The top of this calculator has three fields labeled Feet Inches and Fraction.
You can use all three fields the inches and fraction or the inches fields. The inches field will accept decimal values for those familiar with decimal values. Youre signed out.
Videos you watch may be added to the TVs watch history and influence TV recommendations. To avoid this cancel and sign in to YouTube on your computer. Some say to find the length of jack rafters you measure from the corner of the building where the hip is to the center of your layout mark for the jack and this is the run youd use to multiply by the unit rise on the framing square.
Then deduct half the diagonal thickness of the hip and this is the actual length to cut your stock. Finding the Length of a Jack Rafter. You can find the length of a jack rafter fairly easy.
You have to multiply the value that is in the tables by the position number of the rafter. Once you have this answer you will want to subtract half of the diagonal thickness of the hip. On a regular hip roof when cutting either a hipvalley rafter or jack rafters you set your saw to 45 by adjusting its sole and make a cut that either follows an x12 plumb cut line on a jack or an x17 plumb line on a hipval.
Thats simple enough to both do and understand. You can cut the jack rafter side cut cheek angles using the plan angle as the saw blade bevel angle along the miterplumb line on the side of the jack rafter. In this example the 912 jack rafters would use a saw blade bevel angle of 53130100 to cut the jack rafters side cut cheek angles.
Jack Rafter Plumb and Side Cuts. If youre using a circular Saw or Compound Miter Saw set blade bevel angle to 45 for correct Creeper and Hip side angles. With a 45 bevel on the saw cutting at the plumb cut angle of 58 will produce the correct creeper side angle of 403.
It can be difficult to visualize rafter plumb and side cut angles and. The hangers used to mount the valley jacks to the valley rafter are skewable. An unskewed one is lying flat on the floor beneath one I bent and tack-nailed to the side of the valley rafter.
Using the skewable hanger eliminates the need to make an angle cut on the valley jacks. They can just be square-cut to the short-point measurement. Cutting Compound Angles The cuts made on hip jack and valley jack rafters are typically made at compound angles.
To make such cuts tilt a portable saw at a bevel angle. Then guide it across the rafter stock at a miter angle. Secure the stock so it will not move during the cut.
To prevent the blade guard from binding retract it to get the cut started. A trick for setting the bottom of the hip perfectly is to get it close measure your longest jack on both the major and minor side then calculate and cut the shortest jack for each side and run those two first. How to on cutting valley rafters with a speed squareFirst part cutting hip rafters.
This is also an 8-12 on the main roof and the other a 12-12. My question is how do you figure the jack rafter spacing. My stuff is 16 on center so there is usually quite a few rafters to cut.
When cutting them I always try figure it out mathematically then get upset and end up taking my tape out and messuring them. 05-06-2001 0818 PM. Hip jack cheek cuts.
The fifth line of the framing square side cut of jacks this is for when you cut rafters with a hand saw. We no longer have to use this line as much as framers in years past because when you put the skillsaw on.