The MasterFormat Divisions a Service Trade Lives In

Why this matters

The first time a service shop bids light-commercial work, the drawings arrive with a book several hundred pages thick, and the natural move is to open the shop's own division and ignore the rest. That is how a mechanical contractor ends up owning firestopping it never priced, a plumbing shop misses a closeout requirement that holds back its final payment, and an electrician learns at the punch walk that the training sessions were in its scope. The spec book is organized by a system, and once you know the system you can find every page that binds your trade in under an hour, including the pages filed under somebody else's name.

What the system is

Most commercial specifications in North America are organized by MasterFormat, published by the Construction Specifications Institute (CSI) with Construction Specifications Canada. It gives every kind of work a number and a title, so a specifier in one city and an estimator in another mean the same thing by "23 31 13."

The bound volume is commonly called the project manual. It holds the bidding and contracting documents and the specifications, and the drawings travel with it as a separate set.

Six-digit numbers, read in pairs. Since the 2004 edition, sections carry three pairs of digits:

• The first pair is the division: 23 is HVAC.
• The second pair narrows the family: 23 31 is HVAC ducts and casings.
• The third pair narrows it again: 23 31 13 is metal ducts.

A "00" at the second or third level marks the broader heading, so 23 00 00 is HVAC as a whole and 23 05 00 is the common-work section for HVAC. A fourth level, after a decimal point, appears on some projects for finer breakdowns.

The old numbers still echo. Before 2004 MasterFormat had 16 divisions and five-digit numbers, with nearly all mechanical work, plumbing and fire protection included, in Division 15 and electrical in Division 16. Older techs still say "Division 15," and older specs on renovation jobs may still be written that way. The current structure split those into separate divisions and left gaps reserved for future use, which is why the numbers jump.

Your project's table of contents governs. MasterFormat is revised from edition to edition and specifiers adapt it, so a section number in this card is the common one, not a promise. Always search the project's own contents page.

The table of contents, as a service trade sees it

An excerpt from a project manual for a two-story office renovation, trimmed to the divisions where service trades most often live:

PROJECT MANUAL - TABLE OF CONTENTS (EXCERPT)
DIV 00  PROCUREMENT AND CONTRACTING REQUIREMENTS
DIV 01  GENERAL REQUIREMENTS
  01 10 00  Summary
  01 25 00  Substitution Procedures
  01 26 00  Contract Modification Procedures
  01 31 00  Project Management and Coordination
  01 33 00  Submittal Procedures
  01 40 00  Quality Requirements
  01 77 00  Closeout Procedures
  01 78 00  Closeout Submittals
  01 79 00  Demonstration and Training
DIV 02  EXISTING CONDITIONS
  02 41 19  Selective Demolition
DIV 07  THERMAL AND MOISTURE PROTECTION
  07 84 00  Firestopping
DIV 21  FIRE SUPPRESSION
  21 13 13  Wet-Pipe Sprinkler Systems
DIV 22  PLUMBING
  22 05 00  Common Work Results for Plumbing
  22 11 16  Domestic Water Piping
DIV 23  HEATING, VENTILATING, AND AIR CONDITIONING
  23 05 00  Common Work Results for HVAC
  23 05 93  Testing, Adjusting, and Balancing for HVAC
  23 07 00  HVAC Insulation
  23 31 13  Metal Ducts
DIV 25  INTEGRATED AUTOMATION
DIV 26  ELECTRICAL
  26 05 00  Common Work Results for Electrical
  26 24 16  Panelboards
DIV 27  COMMUNICATIONS
DIV 28  ELECTRONIC SAFETY AND SECURITY
DIV 31  EARTHWORK
DIV 32  EXTERIOR IMPROVEMENTS
DIV 33  UTILITIES

Which divisions belong to which shop

• 21 Fire Suppression: sprinklers and standpipes. Licensed fire sprinkler contractors live here; a plumbing shop reads it for interfaces, such as who brings the water service to the riser.
• 22 Plumbing: piping, fixtures, water heaters, drainage, and plumbing insulation.
• 23 HVAC: equipment, ductwork, piping, insulation, controls for HVAC (23 09 00 on many projects), and testing, adjusting and balancing.
• 25 Integrated Automation: building automation that ties systems together. Where a project uses it, HVAC controls may live here instead of in 23, which changes who owns them.
• 26 Electrical: power, lighting, panels and grounding.
• 27 Communications: data and voice cabling.
• 28 Electronic Safety and Security: fire alarm on many projects, plus access control, intrusion detection and video. An alarm or security shop reads this one.
• 31 Earthwork, 32 Exterior Improvements, 33 Utilities: excavation, paving, landscaping and irrigation, and site utilities. Lawn and irrigation contractors find their work in 32; a plumber connecting to the site water or sewer finds the boundary in 33.

The section most trades skip inside their own division is the common-work section, 22 05 00, 23 05 00 or 26 05 00. It carries the rules that apply to every other section in the division: sleeves and seals, hangers and supports, identification and labeling, motor requirements, and often the matrix of which trade furnishes, installs and wires each item.

Division 01 binds everyone

Division 01, General Requirements, is the procedural rulebook for the whole job, and every technical section points back to it. Three of its sections decide more about a service shop's schedule and cash than any technical paragraph:

• 01 25 00 Substitution Procedures: how and by when to propose a product other than the one specified, what the request must contain, and what happens if it is late. The deadline is often before bids are due, which surprises shops that planned to substitute after award (see related: How to Write a Substitution Request the Engineer Can Approve).
• 01 33 00 Submittal Procedures: format, routing, the review period the designer is allowed, and how many resubmittals before the contractor pays for further reviews. The review period is what you add to every lead time (see related: What a Submittal Review Stamp Means and What It Does Not).
• 01 77 00 Closeout Procedures and 01 78 00 Closeout Submittals: what has to be turned over before substantial completion and final payment, including operation and maintenance manuals, warranties, record documents and spare parts (see related: How to Assemble a Closeout Package).

Around them sit 01 26 00 on how changes are priced and documented, 01 31 00 on coordination and meetings, 01 40 00 on testing and inspections, and 01 79 00 on owner training. A technical section that says "submit product data in accordance with Section 01 33 00" is not repeating the rule; it is incorporating it.

Worked example: mapping one HVAC shop's scope

An HVAC shop is bidding the renovation whose contents appear above: replace two rooftop units, add a duct run to a second-floor suite, and rebalance. The estimator starts with Division 23 and finds four sections in the excerpt: 23 05 00, 23 05 93, 23 07 00 and 23 31 13. The full book adds the equipment section for the rooftop units and the controls section, making six Division 23 sections in scope.

Then the estimator reads 23 05 00 for its references outward, and it names three sections in other divisions:

• 07 84 00 Firestopping. The new duct run crosses a rated corridor wall. The firestopping section says each trade seals its own penetrations with a tested, listed system and submits the listed system drawings. The duct plan shows eight penetrations of that wall. Read alone, Division 23 never mentions firestopping beyond a pointer; read together, the shop owns eight listed seals plus a submittal.
• 02 41 19 Selective Demolition. The section assigns removal of abandoned equipment to the trade that owns the system, so removing and hauling away the two old rooftop units and capping their curbs is in the mechanical scope, not the general contractor's.
• 26 05 00 Common Work Results for Electrical. Its responsibility matrix says the HVAC contractor furnishes the unit disconnects, the electrician installs and wires them. That is a hand-off to price and to schedule.

Division 01 adds three more. 01 25 00 sets substitution requests due ten days before bid in this book, so the alternate rooftop unit the shop prefers has to be submitted now or not at all. 01 33 00 allows the engineer ten working days per review. 01 79 00 requires two hours of owner training on the new units, recorded with a sign-in sheet.

Count it from the list: six sections in Division 23, three outside it in other technical divisions, three in Division 01, so twelve sections bind the shop, and half of them are not in Division 23. An estimator who read only Division 23 priced half the sections that carry obligations, and the missing half are exactly the ones that show up as surprises at the punch walk.

What changes the read

• Small jobs with outline specs. Some light-commercial jobs come with a short-form spec on the drawings instead of a book. The same divisions apply in compressed form, and the notes on the general sheet usually play the part of Division 01.
• Owner standards. Retailers, schools and hospitals often add their own standard sections, sometimes numbered in MasterFormat style and sometimes not. They bind the same way.
• Performance and delegated-design sections change what a section asks of you, from installing a product to designing a result (see related: Basis of Design, Proprietary and Performance Specifications).

References

• MasterFormat, Construction Specifications Institute and Construction Specifications Canada, in the edition your project manual is written to.
• See related: The Three-Part Spec Section: General, Products, Execution
• See related: Reading Construction Plans + Specifications; Reading Bid Documents + Scope Reference
• See related: How to Check Your Scope Against By-Others and NIC Notes
• See related: Specification Compliance and the Or Equal Question