CSI MasterFormat divisions explained

Where MasterFormat comes from

MasterFormat is published by the Construction Specifications Institute (CSI) and Construction Specifications Canada. Older specifications used 16 divisions. The 2004 edition expanded the system to 50 divisions to make room for growing technologies, especially building services, and later editions have continued to refine it. Many divisions are reserved for future use, which is why the numbering has gaps.

How the numbers work

Every section number has three pairs of digits. The first pair is the division, the second is the level-two grouping and the third is the level-three detail. For example, 03 30 00 is Cast-in-Place Concrete within Division 03 Concrete, and 09 29 00 is Gypsum Board within Division 09 Finishes. Specifiers can go further with decimal extensions when a project needs more detail.

The divisions estimators use most

Divisions are grouped into subgroups. Procurement and contracting requirements sit in Division 00 and general requirements in Division 01. The facility construction subgroup runs from Division 02 to 19, the facility services subgroup from 20 to 29, the site and infrastructure subgroup from 30 to 39, and process equipment from 40 to 49.

• 02 Existing Conditions (including demolition)
• 03 Concrete · 04 Masonry · 05 Metals
• 06 Wood, Plastics and Composites · 07 Thermal and Moisture Protection
• 08 Openings · 09 Finishes · 10 Specialties · 11 Equipment
• 14 Conveying Equipment
• 21 Fire Suppression · 22 Plumbing · 23 HVAC
• 26 Electrical · 27 Communications · 28 Electronic Safety and Security
• 31 Earthwork · 32 Exterior Improvements · 33 Utilities

Why estimates follow the divisions

General contractors buy most of their work through subcontracts, and subcontractors tend to align with divisions: a concrete sub, a drywall and ceilings sub, an electrical sub. An estimate organized by division lets the GC compare each subcontractor’s quote with an independent number for the same scope, spot gaps on bid day and decide which trades to self-perform. It also maps neatly onto most estimating and accounting software.

MasterFormat and UniFormat

MasterFormat organizes work by product and trade. UniFormat, also published by CSI, organizes cost by building element, such as substructure, shell, interiors and services. Early in design, when there are no detailed specifications yet, elemental estimates in UniFormat are often more useful. As the design matures, estimates usually move into MasterFormat divisions to match the specifications and the way the work will be bought.

Practical tips for estimators

Keep the division structure even when you price a single trade, because general contractors will compare your number with others by division. Watch the boundaries between divisions: firestopping sits in Division 07, but penetrations through rated walls are often made by MEP trades, and toilet accessories in Division 10 may be supplied by one firm and installed by another. Note which division each boundary item sits in, and say so in your scope letter, so nothing is priced twice or left out.

How MasterFormat helps after award

The division structure stays useful long after bid day. Subcontracts are usually let by division, submittals are numbered by specification section, and cost reports often follow the same codes. When the estimate, the specification and the cost report all use MasterFormat, a change in one place can be traced through the others, which makes change pricing and final accounts much easier to agree.