Every force that acts on a building . from the weight of the structure itself to a snow storm, a windstorm, or an earthquake . must travel through a continuous path of connected structural members before it reaches the ground. That journey is the load path, and understanding it is the foundation of structural design.

Loads fall into two broad families. Gravity loads act downward: dead loads (the permanent weight of materials), live loads (the variable weight of occupants and furnishings), snow, and rain. Lateral loads act horizontally . or can produce uplift . and include wind, seismic ground motion, soil pressure, flood, and tsunami forces. Both families must be accounted for in every structural system.

Tributary area is the concept that links a load to the member carrying it. When you draw lines of equal distance between parallel beams, every floor area within those lines 'belongs' to the beam at the center. The beam must carry the dead and live load of all the tributary square footage it owns. Columns accumulate tributary areas from every floor above them, which is why columns on lower floors carry far more load than those near the roof.

The load path connects every element in a hierarchy: roof sheathing transfers load to rafters or trusses, which transfer to wall top plates, which transfer down through studs or columns, which transfer to footings, which transfer to the soil. Any break in that chain . a missing connection, an undersized fastener, a poorly detailed joint . represents a failure point.

For lateral forces, the lateral force-resisting system (LFRS) takes over. Shear walls and horizontal diaphragms (floors and roofs clad with structural sheathing) work together to capture wind and seismic forces and channel them to the foundation. Without a properly connected LFRS, lateral loads have nowhere to go and the building can rack or overturn.

Building codes . primarily the IBC, which references ASCE 7 . specify minimum load values and the combinations in which they must be checked. You'll combine loads using either Allowable Stress Design (ASD) or Load and Resistance Factor Design (LRFD) methods, each with different factors that reflect the statistical reliability of the loads involved. As an architect sizing structural components and detailing connections, knowing how loads accumulate and transfer gives you the judgment to coordinate effectively with structural engineers and catch problems before they reach the field.