How many rafters are required to frame a gable roof on a 24' x 42' building with rafters spaced at 24" O.C.?

To determine how many rafters are needed to frame a gable roof for a building measuring 24 feet by 42 feet with rafters spaced 24 inches on center, it is important to first convert the spacing from inches to feet. A spacing of 24 inches is equivalent to 2 feet.

Next, you need to consider the run of the roof. Since a gable roof has two sides, we can calculate the run based on the width of the building. The width of the building is 24 feet, and each side of the roof extends over half of that width, resulting in a run of 12 feet on each side.

To find out how many rafters fit along one side of the roof, you start with the length of the building, which is 42 feet. To find the number of spaces for the rafters, you divide the total length of 42 feet by the spacing of the rafters, which is 2 feet.

First, divide 42 by 2, yielding 21. However, remember that the framing also requires a rafter at the beginning and an additional rafter at the end of the run, meaning you need to add one more to account for the last rafter that fits at