If a truss is installed every 2 feet, how many trusses are needed for a 30-foot roof?

To determine how many trusses are needed for a 30-foot roof when trusses are installed every 2 feet, you start by calculating how many 2-foot segments fit into the total length of the roof.

Dividing the total length of the roof (30 feet) by the spacing between each truss (2 feet) gives you:

30 feet ÷ 2 feet = 15

This calculation indicates that there are 15 segments of 2 feet within the 30-foot length. However, when installing trusses, you typically require one additional truss at the end to properly support both ends of the roof, as the first truss is positioned at the start of the measurement (0 feet) and each subsequent truss fills the gap until the final point (30 feet).

As a result, in addition to the 15 segments calculated, you need that one extra truss at the end for complete coverage. Therefore, the total number of trusses needed is:

15 + 1 = 16

Thus, the correct answer is indeed that 16 trusses are required for a 30-foot roof when placed every 2 feet apart.