Final answer:
The allowable beam overhang depends on the material, size, load, and design, with an overhang up to 1/4 of the span being typical, but always refer to local building codes and design principles for safety.
Step-by-step explanation:
The question of how much beam overhang a post can have is related to structural engineering, a component of civil engineering. This involves understanding the load-bearing capacities of different materials and construction methods. The allowable overhang for a beam largely depends on factors such as the type of material used for the beam, the size of the beam, the type of loads it will carry, and the overall design of the structure. Typically, the overhang of a beam can be up to 1/4 of the actual supported span of the beam, but this can vary. Always refer to the local building codes and structural design principles when determining the precise allowable overhang for safety and compliance reasons.