MasterFormat is the standard list of numbers and titles that North American construction projects use to organise their specifications. Published by the Construction Specifications Institute (CSI) with Construction Specifications Canada (CSC), it sorts the work into 50 divisions numbered 00 to 49, each split into sections with six-digit numbers such as 08 71 00 Door Hardware. Division 03 is concrete, 08 openings, 09 finishes, 23 HVAC, 26 electrical. The current edition is MasterFormat 2026, which CSI says adds 2,185 new listings and reorganises 617 existing ones. This guide lists the divisions, explains how to read a section number, and shows how the specifications connect to the drawings.
The MasterFormat divisions
The divisions are arranged in groups and subgroups. Numbers that are skipped (15 to 20, 24, 29, 30, 36 to 39, 47 and 49) are left open for future use. The titles below are the published division titles; CSI's 2026 edition keeps most content in the same divisions, but check your subscription for the exact current wording.
| Group or subgroup | Divisions |
|---|---|
| Procurement and Contracting Requirements | 00 Procurement and Contracting Requirements (bidding documents, contract forms, conditions of the contract) |
| General Requirements | 01 General Requirements (administration, submittals, quality, temporary facilities, closeout) |
| Facility Construction | 02 Existing Conditions, 03 Concrete, 04 Masonry, 05 Metals, 06 Wood, Plastics, and Composites, 07 Thermal and Moisture Protection, 08 Openings, 09 Finishes, 10 Specialties, 11 Equipment, 12 Furnishings, 13 Special Construction, 14 Conveying Equipment |
| Facility Services | 21 Fire Suppression, 22 Plumbing, 23 Heating, Ventilating, and Air Conditioning (HVAC), 25 Integrated Automation, 26 Electrical, 27 Communications, 28 Electronic Safety and Security |
| Site and Infrastructure | 31 Earthwork, 32 Exterior Improvements, 33 Utilities, 34 Transportation, 35 Waterway and Marine Construction |
| Process Equipment | 40 Process Interconnections, 41 Material Processing and Handling Equipment, 42 Process Heating, Cooling, and Drying Equipment, 43 Process Gas and Liquid Handling, Purification and Storage Equipment, 44 Pollution and Waste Control Equipment, 45 Industry-Specific Manufacturing Equipment, 46 Water and Wastewater Equipment, 48 Electrical Power Generation |
For a typical building, the divisions an architect works in most are 01 and 03 to 14. The engineers' work sits in 21 to 28 (fire protection, plumbing, mechanical, electrical, low voltage) and 31 to 33 (civil and site).
How to read a MasterFormat number
A section number is three pairs of digits, read from broad to narrow, with an optional fourth pair after a decimal point:
- 08 00 00: the division (Openings).
- 08 70 00: a group of sections within it (Hardware).
- 08 71 00: the section (Door Hardware).
- 08 71 00.13: an optional fourth level for an even narrower topic, used by some offices and master specifications.
The six-digit numbers date from the 2004 edition, when MasterFormat grew from 16 divisions to 50. The same door hardware section used to be 08710, and older project manuals and some owner standards still use the five-digit form, so you will meet both.
What changed in MasterFormat 2026
CSI describes the 2026 edition as a significant update: 2,185 new listings and 617 reorganised ones. Two divisions account for more than 80% of the structural changes: Division 32 Exterior Improvements (a large expansion of site and landscape systems) and Division 34 Transportation (restructured for infrastructure). Divisions 28 Electronic Safety and Security and 31 Earthwork were also expanded, while Divisions 01, 06, 09, 10 and 26 received mainly title clarifications and small reorganisations. CSI notes that most changed content stays in the same division. Earlier editions were published in 2010, 2011, 2012, 2014, 2016, 2018 and 2020, and many firms' master specifications still follow one of those.
MasterFormat 2026 is distributed through CSI's Dynamic Standards subscription, which bundles MasterFormat, UniFormat and OmniClass. Without a subscription only a limited set of numbers and titles can be looked up.
Inside a section: the three parts
MasterFormat decides which section a topic goes in; CSI's companion standard, SectionFormat, decides what goes inside it. Almost every specification section has three parts:
- Part 1 General: scope, references, submittals, quality assurance, warranty.
- Part 2 Products: materials, products and systems, often with acceptable manufacturers.
- Part 3 Execution: preparation, installation, field quality control, cleaning and protection.
When a part has nothing to say, the title stays and the text reads "Not used".
How specifications and drawings work together
The drawings show where things go, how much and how they fit; the specifications say what they are and how to install them. MasterFormat numbers are the link between the two:
- Keynotes on drawings often use the section number as the key, for example a note "09 30 13" pointing to the ceramic tiling section.
- Schedules on the drawings point into the specifications: a door schedule's hardware set number refers to the hardware sets in 08 71 00, and a room finish schedule uses codes defined in the Division 09 sections.
- Submittals are usually numbered and logged by section, so a shop drawing for door hardware is filed as 08 71 00. See shop drawings vs submittals.
- Cost estimates at the construction documents stage are often organised by division.
If a drawing and the specification disagree, the contract's order of precedence decides which governs; check where your contract sets it out. Our guide to construction documents explains how drawings, specifications and the contract fit together.
MasterFormat, UniFormat and OmniClass
| System | Organises by | Typical use |
|---|---|---|
| MasterFormat | Work results (what a trade builds or installs) | Specifications, bidding, detailed cost estimates |
| UniFormat | Building elements and systems (substructure, shell, interiors, services) | Early design estimates, preliminary project descriptions |
| OmniClass | Many tables, including work results based on MasterFormat | Classifying objects in BIM and facility data |
A project often starts with a UniFormat estimate and moves to MasterFormat once there are specifications.
Common mistakes
- Mixing five-digit (16-division) and six-digit numbers in one project manual.
- Referencing a section on the drawings that is not in the project manual, or was renumbered in a later edition.
- Repeating product requirements on the drawings that are already in the specification, so the two can drift apart.
- Putting administrative requirements in a technical section instead of Division 01.
- Assuming every project uses the latest edition; the project manual's table of contents is what counts.
Frequently asked questions
How many divisions are in MasterFormat?
Fifty, numbered 00 to 49, of which some numbers are left open for future use. Before 2004 there were 16.
What is the current edition of MasterFormat?
MasterFormat 2026, distributed through CSI's Dynamic Standards subscription.
What is Division 9 in construction?
Finishes: plaster and gypsum board, tiling, ceilings, flooring, wall finishes and painting.
What is Division 8 in construction?
Openings: doors and frames, windows, skylights, hardware, glazing and louvers.
What do the numbers in a spec section mean?
The first pair is the division, the second a group within it, the third the section; an optional fourth level follows a decimal point.
Is MasterFormat the same as CSI divisions?
Yes. "CSI divisions" is the everyday name for the divisions of MasterFormat.
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Related: what are construction documents, types of construction documents, shop drawings vs submittals, general notes on drawings.
All product names, standards and organisations mentioned on this page are trademarks or registered names of their respective owners and are used for identification only. MasterFormat, UniFormat and OmniClass are trademarks of the Construction Specifications Institute. Ncored is an independent product by Noir architects and is not affiliated with, sponsored by, or endorsed by any of them. This page summarises published information about MasterFormat; the current CSI publication and your project manual govern. Individual experiences may vary.