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CSI MasterFormat divisions: all 50, from 00 to 49.
Every division number and title in MasterFormat 2026, grouped the way CSI groups them. 35 divisions are in use and 15 numbers are held in reserve for future expansion. Search the list, print it, or download a copy to keep.
By Nicolás PlateroCCO
The MasterFormat division list
Division numbers and titles as CSI publishes them, in CSI’s groups and subgroups. The 15 reserved numbers are listed too, in gray: they hold no sections today and keep room in the numbering for future expansion.
MasterFormat® is published by the Construction Specifications Institute (CSI) and Construction Specifications Canada (CSC). This page lists division numbers and titles only. For the sections inside each division, see the official publication at csiresources.org.
Showing 50 of 50 divisions
Procurement and Contracting Requirements Group
Division 00| Division | Title |
|---|---|
| 00 | Procurement and Contracting Requirements |
Specifications Group
General Requirements Subgroup
Division 01| Division | Title |
|---|---|
| 01 | General Requirements |
Facility Construction Subgroup
Divisions 02 to 19| Division | Title |
|---|---|
| 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 |
| 15 | Reserved for Future Expansion |
| 16 | Reserved for Future Expansion |
| 17 | Reserved for Future Expansion |
| 18 | Reserved for Future Expansion |
| 19 | Reserved for Future Expansion |
Facility Services Subgroup
Divisions 20 to 29| Division | Title |
|---|---|
| 20 | Reserved for Future Expansion |
| 21 | Fire Suppression |
| 22 | Plumbing |
| 23 | Heating, Ventilating, and Air Conditioning (HVAC) |
| 24 | Reserved for Future Expansion |
| 25 | Integrated Automation |
| 26 | Electrical |
| 27 | Communications |
| 28 | Electronic Safety and Security |
| 29 | Reserved for Future Expansion |
Site and Infrastructure Subgroup
Divisions 30 to 39| Division | Title |
|---|---|
| 30 | Reserved for Future Expansion |
| 31 | Earthwork |
| 32 | Exterior Improvements |
| 33 | Utilities |
| 34 | Transportation |
| 35 | Waterway and Marine Construction |
| 36 | Reserved for Future Expansion |
| 37 | Reserved for Future Expansion |
| 38 | Reserved for Future Expansion |
| 39 | Reserved for Future Expansion |
Process Equipment Subgroup
Divisions 40 to 49| Division | Title |
|---|---|
| 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 |
| 47 | Reserved for Future Expansion |
| 48 | Electrical Power Generation |
| 49 | Reserved for Future Expansion |
A note on Division 40: CSI’s 2026 overview page labels it Process Integration. CSI’s 2018 master list and the Division 40 page on The Construction Standard use Process Interconnections, the title shown here.
What MasterFormat is and what it is used for
CSI calls MasterFormat “the construction industry’s standardized language for project documentation.” It organizes construction information into work results, the work contractors price, procure and build, and every specification section carries a six digit number that starts with its two digit division.
Specifications
A project manual is organized by division and section, so anyone on the team can find the requirements for openings in Division 08 or finishes in Division 09 without reading the whole book.
Pricing and buying
Because the divisions follow the work contractors price and procure, estimates, bids and buyouts can be broken down the same way the specifications are.
Project records
Submittals and product data are usually filed by specification section number, which is why a submittal log starts with that number. Even the National CAD Standard files its floor plan symbols by MasterFormat number.
What changed in MasterFormat 2026
CSI calls the 2026 edition a significant update: it adds 2,185 new listings and reorganizes 617. According to CSI, this is where the changes land:
- Largest changes. Division 32 (Exterior Improvements) gets a large expansion of site and landscape systems, and Division 34 (Transportation) is restructured for infrastructure classification. Together they account for more than 80% of the structural changes.
- Noticeable expansion. Division 28 (Electronic Safety and Security) and Division 31 (Earthwork).
- Maintenance updates, mainly title clarifications or small reorganizations: Divisions 01, 06, 09, 10 and 26.
- Largely stable: Divisions 02, 07, 27 and 40.
CSI says the majority of the changed content stays in the same divisions, and its notes do not announce any new, removed or renamed division. The division titles on this page match CSI’s 2018 master list.
From 16 divisions to 50
MasterFormat had 16 divisions from the early 1960s until the 2004 edition, which expanded it to 50 (numbered 00 to 49) and moved to six digit section numbers. The last CSI edition with 16 divisions was published in 1995.
The biggest move was mechanical and electrical work. The old Division 15, Mechanical, was split into Divisions 21 (Fire Suppression), 22 (Plumbing) and 23 (HVAC). The old Division 16, Electrical, became Divisions 25 to 28, from Integrated Automation to Electronic Safety and Security. Numbers 15 and 16 are now reserved, so a spec that still says “Division 15” for mechanical work is using the pre 2004 system.
MasterFormat and UniFormat: the difference
MasterFormat organizes specifications into work results, the parts of the work that contractors price, procure and build. That is why it gives a project manual its structure, division by division and section by section.
UniFormat, also published by CSI and CSC, arranges the same building by functional elements, such as substructure, shell, interiors and services, without regard to the materials and methods used to build them. CSI names its primary use as a format for estimators to present cost estimates during schematic design. In short: UniFormat describes what each part of the building does, and MasterFormat describes the work that builds it.
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Questions, answered
What are the 50 divisions of CSI MasterFormat?
MasterFormat numbers its divisions from 00 to 49. Division 00 covers procurement and contracting requirements and Division 01 general requirements. Divisions 02 to 14 cover facility construction, from existing conditions and concrete to conveying equipment. Facility services run from 21 to 28, site and infrastructure from 31 to 35, and process equipment from 40 to 48. 15 numbers are reserved for future expansion, so 35 divisions are in use.
What happened to the old 16 divisions?
They were replaced in 2004, when MasterFormat expanded from 16 divisions to 50 and moved to six digit section numbers. The old Division 15, Mechanical, became Divisions 21 (Fire Suppression), 22 (Plumbing) and 23 (HVAC). The old Division 16, Electrical, became Divisions 25 to 28, from Integrated Automation to Electronic Safety and Security. Numbers 15 and 16 are now reserved for future expansion.
How many MasterFormat divisions are actually used?
35. MasterFormat numbers its divisions from 00 to 49, but 15 of those numbers are reserved for future expansion: 15 to 20, 24, 29, 30, 36 to 39, 47 and 49. CSI prints them in its master list as Reserved for Future Expansion, so they keep their place in the numbering even though they carry no work today. The other 35, from Procurement and Contracting Requirements to Electrical Power Generation, are the ones with sections in them.
What changed in MasterFormat 2026?
According to CSI, MasterFormat 2026 adds 2,185 new listings and reorganizes 617. Divisions 32 (Exterior Improvements) and 34 (Transportation) account for more than 80% of the structural changes, Divisions 28 and 31 grew noticeably, and Divisions 01, 06, 09, 10 and 26 got maintenance updates. CSI's notes do not announce any new, removed or renamed division, and the division titles match CSI's 2018 master list.
What is the difference between MasterFormat and UniFormat?
MasterFormat organizes construction information by work results, the work contractors price, procure and build, and it gives specifications their structure. UniFormat, also from CSI and CSC, organizes a building by functional elements such as substructure, shell, interiors and services, without naming materials or methods. CSI describes its primary use as presenting cost estimates during schematic design. In short, UniFormat describes what each part does and MasterFormat the work that builds it.
Where can I get the full list of MasterFormat sections?
From CSI. This page covers division numbers and titles only. The sections inside each division, with their numbers, titles and explanations, are in the official MasterFormat publication, which CSI licenses under its end user license agreement. CSI also asks anyone planning a commercial product or resource built on MasterFormat numbers or titles to contact CSI first.
Sources: CSI, MasterFormat 2026: what's new; CSI, Standards overview (MasterFormat and UniFormat); CSI, Standards FAQs: MasterFormat; CSI, About UniFormat; CSI MasterFormat 2018, Master List of Numbers, Titles, and Explanations (copy hosted by AGC Austin); The Construction Standard, MasterFormat Division 40: Process Interconnections; Consulting Specifying Engineer, MasterFormat 2004: A Major Step Forward for Construction Project Delivery (2005); Wikipedia, MasterFormat.
Last updated September 23, 2026.