For a flat roof on a 30' x 66' building with a 2'-6" overhang, how many pieces of 4 x 8 plywood are needed?

To determine how many pieces of 4 x 8 plywood are needed for a flat roof on a building, start by calculating the total area of the roof, including the overhang.

First, calculate the dimensions of the building, which is 30 feet by 66 feet. The overhang on each side of the building is 2 feet 6 inches, which must be added to the total dimensions. There are two 2'-6” overhangs on the 30-foot sides, contributing a total of 5 feet to the width. For the length, only the overhangs on the shorter sides will be considered, adding 2'-6" to both shorter lengths, contributing an additional 5 feet to the total length.

Adding these measurements gives the effective dimensions of the roof:

• Width: 30' + 5' (overhangs) = 35'

• Length: 66' + 0' (no length overhang; only width overhang) = 66'

Now, calculate the area of the roof:

Area = Width × Length = 35' × 66' = 2310 square feet.

Next, calculate the area of one piece of 4 x 8 plywood