UniFormat and MasterFormat

The difference in one line

UniFormat asks what part of the building this is. MasterFormat asks what trade does the work. Everything else follows from that.

The differences that matter in practice

• Organizing principle. UniFormat II classifies building elements, defined in NISTIR 6389 as major components that perform a given function "regardless of the design specification, construction method, or materials used". MasterFormat organizes specifications "into work results that contractors can price, procure, and build" (CSI standards overview).
• Code form. UniFormat II codes are alphanumeric and begin with a letter, in a widening hierarchy: A, then A10, then A1010. MasterFormat codes are numeric and begin with a two-digit division number: 03, 26, 31.
• Size and shape of the two lists. The ASTM E1557-97 classification reproduced in NISTIR 6389 has 7 level-1 major group elements, 22 level-2 group elements, and, per section 2.1 of the report, 57 level-3 building elements plus 22 level-3 sitework elements. MasterFormat occupies 50 division numbers, 00 through 49, of which 35 carry titles and 15 are held for future expansion.
• Publishers. UniFormat is a registered trademark of CSI and CSC, and the same element classification is published by ASTM as standard E1557 and by NIST as NISTIR 6389 (Charette and Marshall, October 1999). MasterFormat is published by CSI in collaboration with CSC, and has no ASTM or NIST equivalent.
• Point in the project where each is used. Wikipedia's CSI article states that "Titles in UniFormat Levels 1 through 3 can be applied to most project descriptions and preliminary cost estimates"; CSI's standards page ties UniFormat to "cost analysis and early project design documentation". MasterFormat carries through to the construction documents and procurement, since its sections are what a contractor prices and buys.
• Treatment of sitework. UniFormat II keeps the building (A through F) separate from building-related sitework (G), and NISTIR 6389 states plainly that "UNIFORMAT II is not intended to classify elements of major civil works." MasterFormat distributes site work across divisions 31 to 35 and reserves 40 to 49 for process equipment, so it covers work well beyond a building.
• The relationship between them is many-to-many, not one-to-one. Chart 4.5 of NISTIR 6389, reproduced from the AIA Architect's Handbook of Professional Practice (1984), marks a single element such as Exterior Closure against masonry, metals, wood, thermal and moisture protection, and doors and windows at the same time. A single division likewise feeds several elements: concrete appears under foundations, superstructure and stairs.
• Revision history. MasterFormat editions are recorded for 1963, 1966, 1972, 1978, 1995, 2004, 2010, 2011, 2012, 2014, 2016, 2018 and 2020, and it expanded from 16 divisions to 50 in November 2004. The UniFormat II level-1 and level-2 titles in the 1997 ASTM version have changed comparatively little, which follows from classifying by function rather than by product.
• Mark-ups and project-wide costs. NISTIR 6389 adds Z designators for design allowance, overhead and profit, and inflation, and states that "these designators are not incorporated in the ASTM E1557 standard because E1557 is a classification of building elements only, and not an estimating standard." MasterFormat holds the comparable commercial and administrative content in Division 00 and Division 01.
• Depth of the hierarchy. ASTM E1557-97 defines three levels, and NISTIR 6389 proposed a fourth level of sub-elements (wall foundations, column foundations, perimeter drainage, insulation, and so on). MasterFormat section numbers are all-numeric and open with the two-digit division, with further pairs of digits narrowing the subject.

Scope and ownership

This publishes numbers and titles only: UniFormat levels one and two, and the MasterFormat division numbers. The level-three and level-four elements and the six-digit sections are not here and will not be added.

MasterFormat and UniFormat are registered trademarks of the Construction Specifications Institute and Construction Specifications Canada, who publish and sell the standards. The UniFormat data here follows ASTM E1557-97 as set out in NISTIR 6389, which NIST publishes free.