Every building project starts with a fundamental question: how big can this building actually be? The IBC answers that through Table 503, which sets maximum height (in feet), stories (above grade plane), and area per story (in square feet) based on two intersecting variables: construction type and occupancy classification.

Construction type ranges from Type I (protected noncombustible, like concrete and fireproofed steel) down to Type V (fully wood-framed). Occupancy classification groups buildings by function and risk level, from Assembly (A) through Storage (S). Where these two factors meet on Table 503, you get your baseline limits.

But the code doesn't stop at the table. Sections 504 and 506 provide formulas for increasing those limits. A fully sprinklered building can gain 20 additional feet of height and one extra story. The allowable area per story can jump dramatically through frontage increases (Equation 5-2) and sprinkler increases (Equation 5-1). Section 507 even permits unlimited area buildings under specific conditions.

For the ARE, you need to know how to read Table 503, apply the modification formulas, and understand how fire walls, mixed-use occupancies, and unlimited area provisions change the math. These calculations appear on the exam as scenario-based problems where you determine whether a proposed building meets code requirements.