How many rolls of R-13 insulation are required to insulate the walls of the garage shown in Figures 15.16 and 15.17? The insulation comes in rolls 15 inches wide by 56 feet long. On the gable ends of the building (east and west ends), the insulation is run to the underside of the rafters. Be sure to deduct the area of the garage door, but do not deduct the area of the personnel door. The west side of the building is similar to the east side.

Question

What will be an ideal response?

Answer 1

Find the area of the wall as follows:

Area of north wall = 8?1? × 30? = 243 sf

Area of east wall = 8?1? × 24? + 0.5 × 4? × 24? – 7? × 16? = 130 sf

Area of south wall = 8?1? × 30? = 243 sf

Area of west wall = 8?1? × 24? + 0.5 × 4? × 24? = 242 sf

Total wall area = 243 sf + 130 sf + 243 sf + 242 sf = 858 sf

Effective coverage per roll = 16? × 56? / 12 in per ft = 75 sf

Rolls of insulation = 858 sf of walls / 75 sf of coverage per roll = 11.44 rolls – Use 12 rolls