Fig. 13. - Diagram for Finding Area of a Gable.

Fig. 14. - Finding Area of Gable when Roof is Less than Half Pitch.

Referring to Fig. 13, A B C represents the gable of a building of which A C is the width and D B is the perpendicular hight. By dividing the gable on the line D B we have two triangles of equal areas and equal sides. It is evident that if the triangle D B C is placed in the position shown by the dotted lines A E B, it will form a square whose side is equal to one-half the width of the gable. This of course applies to gables on buildings of a half pitch roof. With a roof of less pitch a rectangle would be formed with A D for its length and D B for its breadth, as shown in Fig. 14. In this figure the triangle A B C is equal in area to the rectangle A E B D. From the foregoing illustrations and principles we derive the following:

Rule. - Multiply one-half the width of the gable by the perpendicular hight.

For example, if a gable is 24 feet wide and the perpendicular hight is 8 feet, then 24 ½ ½ x 8 = 96 feet, the area of the gable.