Structural calculations

Structural calculations are the engineer's demonstration that beams, columns, footings, connections, and the lateral system are adequate for the loads the code assigns them: dead, live, wind, seismic, and any others that apply.

Where it applies in the lifecycle

Prepared during Preparation and reviewed during Plan review. They are supporting evidence rather than construction documents, so they do not travel to the field the way the drawings do; the inspector checks the drawings, which the calculations justify.

When they are required

• New structures, and additions
• Removal or alteration of load-bearing walls
• New openings in structural walls
• Foundation work
• Anything where the reviewer is not willing to accept prescriptive tables

Prescriptive versus engineered

Much residential work can be built from prescriptive code tables, which give allowable spans and sizes directly, with no engineer involved. Once a design steps outside the tables, in span, height, geometry, or load, it becomes an engineered design and requires sealed calculations.

Sealing

Where calculations are required, they are typically sealed by a professional engineer licensed in the state where the project is built. A seal from an out-of-state engineer is not transferable, and a package sealed by someone not licensed in the state is rejected at intake.