Repairing Cracked Rafters

Make a Sister Rafter

• 1

  Determine the size, length, width, and height of the old cracked rafter, using the tape measure.

• 2

  Cut a new rafter the exact size as the cracked one, using the circular saw.

• 3

  Compare the cracked rafter with its neighboring rafters to see if's has dropped out of position. If the rafter is in its proper position, skip step 4.

• 4

  Use a hydraulic jack to move the cracked rafter back into position. Position the jack on a ceiling joist. Shore up the ceiling joist with a temporary 4-by-4-inch board placed over a floor joist.

• 5

  Place the new rafter in position, right against the cracked rafter. Nail the new rafter into position with the hammer and nails.

• 6

  Cut a scab board from the same size board used to make the sister rafter, using the circular saw. The board should be long enough to extend about a foot past either side of the crack. Nail it on the side of the damaged rafter away from the sister rafter.

Shoring Up the Repair

• 7

  Use the circular saw to cut two 2-by-6-inch boards to be used as short trusses, which must be long enough to connect the joist to the rafters.

• 8

  Position the trusses on either side of the cracked rafter. Nail one end of the short truss to the sister rafter and the other end to the joist under the rafter. Nail the other short truss to the cracked rafter and joist in the same manner.

• 9

  Nail a 2-by-6-inch board horizontally under the cracked rafter, attaching it to two or three undamaged rafters on either side of the damaged rafter. Make sure the board passes directly under the damaged area of the cracked rafter. Nail the board into the sister rafter and undamaged neighboring rafters, but not into the cracked rafter.

• 10

  Use the saw to make 2-by-6-inch boards long enough to run from the ceiling joist to the horizontal 2-by-6 you installed in the previous step. Use the hammer to nail one end to the joist and the other end to the horizontal 2-by-6.

• 11

  Remove the hydraulic jack and the temporary 4-by-4-inch board shoring.