Level 1

Area Limitations (Table 506.2)

Size Matters

Chapter 5: General Building Heights & Areas

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Welcome to Building Heights & Areas: Chapter 5

Level 1: Understanding Area Limitations

You've learned how to classify buildings by use (Chapter 3) and by construction type (Chapter 6). Now comes the critical question that determines if your building design is even possible:

"How big can this building be?"

Why This Matters

Area limitations directly affect project feasibility and cost. A developer wants to maximize rentable space. An architect needs to know if the program will fit. A code official must verify the building doesn't exceed its limits. Get this wrong early in design, and you're looking at expensive redesigns or construction type upgrades that blow the budget.

The Core Principle

The IBC limits building area based on two factors working together:

  • Occupancy (how the building is used)
  • Construction Type (what it's made of)

Higher-risk occupancies and less fire-resistant construction = smaller allowable area. Lower-risk occupancies and more fire-resistant construction = larger allowable area.

Your Building: The 3-Story Mixed-Use Project

We'll continue using the building from Chapter 3:

1st Floor: 8,000 SF retail store (Group M)
2nd Floor: 8,000 SF professional offices (Group B)
3rd Floor: 8,000 SF apartments (Group R-2)
Fire Protection: Fully sprinklered (NFPA 13)

The question: What construction type do we need to make this building work? Can we use economical wood framing, or do we need expensive steel/concrete?

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