Roof Rafter Installation

Marking and cutting rafters is only half the job of framing a roof. Those rafters have to be installed properly. That is at least a two-person job and will go better with three or four, even on a small roof. The first task obviously is cutting the rafters correctly, so the top or plumb cuts make a peak and a "birdsmouth" notch is properly cut to fit tightly over the cap board on the outer wall. That can be accomplished with a framing square and circular saw.

Things You'll Need

  • 8- or 10-foot stepladders
  • Tape measure
  • Pencil
  • Rafters
  • Framing nails
  • Hammer
  • Level
  • Ridge board
  • 2--by-4-inch framing lumber
  • Hurricane ties

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Assemble all the rafters and set them in pairs. Raise an 8- or 10-foot stepladder on each wall at one end of the roof, preferably the back. Use a tape measure and pencil to mark all rafter locations, starting at the end. Mark both edges for a 2-inch wide rafter (which actually is 1 1/2 inches wide). Space the centers of rafters 24 inches apart. Mark locations on both walls.

Have one person on each ladder raise a rafter into place (better with two people, one on each end of the rafter). Set the birdsmouth notch on the wall cap; make sure it is a tight fit. Drive one framing nail with a hammer through the birdsmouth into the cap, on each rafter. Test the peak; put a short piece of 2-inch board between the plumb cuts to simulate a ridge board. If the peak is good, remove the test board, use a level to make sure the rafters are plumb and drive a second nail into each birdsmouth.

Repeat the rafter installation at the other end of the roof. Make sure those rafters are plumb and secure. Measure the length between rafter ends and get a 2-inch thick ridge board (4 or 6 inches deep, depending on the roof) to fit between the end rafters. Use one board if possible; if the length is too much, splice two boards by cutting comparable boards to overlap the joint about a foot on each side, nailed to the two boards. Space the splice to fit between two rafters, so each side will be fully supported by one rafter pair.

Install the ridge board by sliding it between the plumb cuts at each end from the bottom. Nail it in place with one framing nail in each rafter on each side. Use a level to make sure it is level. Add other rafter pairs one at a time, on the 24-inch marked spots. Nail each rafter through its birdsmouth to the wall cap and to the rafters. Check each location with a level to keep the ridge board level. Once the ridge board is set, add a second nail in each rafter.

Work down the roof until all rafters are installed. Measure the distance between the bottom of the ridge board and the end wall cap and cut a 2-by-4-inch "gable stud" to fit. Nail that stud in place on each end.

Add cross ties, 2-by-4s cut to fit between the rafters on each side about a third of the way down from the peak to the ceiling level, for extra strength. Install "hurricane ties" at each birdsmouth. These are metal straps that nail to the rafter and to the cap boards on each side of each rafter.


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