What type of beam is supported only at one end?

A cantilever beam is defined as a beam that is supported at one end while the other end extends freely without support. This structure is unique in that it allows for significant overhangs, making it ideal for certain architectural styles and designs where space needs to be utilized efficiently. The unrestrained end experiences moments and forces that must be carefully calculated to ensure the structural integrity of the beam and the overall framework.

In contrast, an overhanging beam is supported at one end and extends beyond its support, but it has an additional support somewhere in the span. A purlin, on the other hand, is a horizontal structural member that supports the roof or wall sheathing and is typically supported at both ends. Lastly, a truss is an assembly of members that creates a rigid framework, typically supported at multiple points rather than just one. Thus, the distinct characteristic of being supported solely at one end clearly identifies the cantilever as the correct answer.