Understanding CSI MasterFormat Divisions

The Construction Specifications Institute (CSI) MasterFormat is the standard indexing system used in North America for organizing construction data, specifications, and estimating budgets.

Why MasterFormat Matters

Before MasterFormat, every architect and contractor organized specifications differently. By standardizing construction into 50 major divisions, MasterFormat ensures that communication across trades is uniform.

When preparing a Bill of Quantities (BOQ), estimators code every line item with its corresponding CSI code.

The Core Divisions (1995 vs 2004+)

While the old 16-division format is still sometimes seen, modern estimates use the expanded 50-division format.

Division 00-01: General Requirements

Division 00: Procurement and Contracting Requirements
Division 01: General Requirements (Overhead, PMs, Temp Facilities)

Division 02-14: Facility Construction

Division 02: Existing Conditions (Demolition)
Division 03: Concrete
Division 04: Masonry
Division 05: Metals (Structural Steel)
Division 06: Wood, Plastics, and Composites (Lumber)
Division 07: Thermal and Moisture Protection (Roofing)
Division 08: Openings (Doors and Windows)
Division 09: Finishes (Drywall, Painting, Flooring)

Division 21-28: Facility Services (MEP)

Division 21: Fire Suppression
Division 22: Plumbing
Division 23: Heating, Ventilating, and Air Conditioning (HVAC)
Division 26: Electrical
Division 27: Communications

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Last Reviewed: July 2026
Standards Referenced: CSI MasterFormat
Next Review: January 2027