| C-2 Insulation and Acoustical Contractor | Thermal and sound insulation, including blown, batt and acoustical ceiling materials. | 1,210 |
| C-4 Boiler, Hot Water Heating and Steam Fitting Contractor | Boilers, hot-water heating systems and steam piping. | 708 |
| C-5 Framing and Rough Carpentry Contractor | Wood framing, rough carpentry, sheathing and structural wood members. | 1,093 |
| C-6 Cabinet, Millwork and Finish Carpentry Contractor | Cabinets, built-ins, trim, doors and other finish woodwork. | 4,450 |
| C-7 Low Voltage Systems Contractor | Low-voltage wiring for communications, alarms, data, sound and similar systems (not fire alarm systems). | 4,909 |
| C-8 Concrete Contractor | Forming, pouring, finishing and repairing concrete: slabs, driveways, foundations and flatwork. | 5,608 |
| C-9 Drywall Contractor | Gypsum wallboard installation, taping and texturing. | 3,335 |
| C-10 Electrical Contractor | Electrical wiring, panels, fixtures and equipment for generating, carrying and using electricity. | 29,124 |
| C-11 Elevator Contractor | Installing, maintaining and repairing elevator systems. | 221 |
| C-12 Earthwork and Paving Contractors | Excavation, grading, trenching and asphalt or concrete paving. | 2,498 |
| C-13 Fencing Contractor | Fences, gates and related barriers of any material. | 1,905 |
| C-15 Flooring and Floor Covering Contractors | Hardwood, laminate, vinyl, carpet and other floor coverings. | 7,112 |
| C-16 Fire Protection Contractor | Fire sprinkler and other fire suppression systems. | 2,266 |
| C-17 Glazing Contractor | Windows, glass doors, storefronts, mirrors and other glass installation. | 3,162 |
| C-20 Warm-Air Heating, Ventilating and Air-Conditioning Contractor | Furnaces, heat pumps, air conditioning, ductwork and ventilation. | 12,227 |
| C-21 Building Moving/Demolition Contractor | Demolishing structures and moving whole buildings. | 1,889 |
| C-22 Asbestos Abatement Contractor | Removing, encapsulating and disposing of asbestos-containing materials. | 320 |
| C-23 Ornamental Metal Contractor | Decorative metal railings, gates, grilles and similar work. | 1,107 |
| C-27 Landscaping Contractor | Planting, irrigation, hardscape, garden walls and other landscape construction. | 12,644 |
| C-28 Lock and Security Equipment Contractor | Locks, door hardware, safes and security equipment. | 375 |
| C-29 Masonry Contractor | Brick, block, stone and other masonry construction. | 2,118 |
| C-31 Construction Zone Traffic Control Contractor | Temporary traffic control in work zones: signs, barricades and striping. | 482 |
| C-32 Parking and Highway Improvement Contractor | Parking-lot striping, signage, curb stops and highway safety features. | 518 |
| C-33 Painting and Decorating Contractor | Interior and exterior painting, coatings and wall coverings. | 16,194 |
| C-34 Pipeline Contractor | Underground and above-ground pipelines for water, gas, sewer and other fluids. | 554 |
| C-35 Lathing and Plastering Contractor | Lath, plaster and stucco systems, inside and out. | 1,882 |
| C-36 Plumbing Contractor | Water, drain, waste, vent and gas piping and fixtures inside a property. | 18,279 |
| C-38 Refrigeration Contractor | Commercial and residential refrigeration equipment and walk-in coolers. | 1,662 |
| C-39 Roofing Contractor | Roof coverings of every type, plus waterproofing on roofs. | 5,805 |
| C-42 Sanitation System Contractor | Septic tanks, leach fields and sewer connections. | 978 |
| C-43 Sheet Metal Contractor | Sheet-metal fabrication and installation, such as ducts, gutters and flashing. | 1,315 |
| C-45 Sign Contractor | Fabricating and installing electrical and non-electrical signs. | 887 |
| C-46 Solar Contractor | Solar thermal and photovoltaic systems. | 1,184 |
| C-47 General Manufactured Housing Contractor | Installing, repairing and setting up manufactured and mobile homes. | 459 |
| C-49 Tree and Palm Contractor | Tree and palm planting, pruning, trimming and removal. | 665 |
| C-50 Reinforcing Steel Contractor | Rebar and other steel reinforcement for concrete. | 258 |
| C-51 Structural Steel Contractor | Erecting structural steel shapes, plates and frames. | 1,583 |
| C-53 Swimming Pool Contractor | Building and remodeling swimming pools and spas. | 2,951 |
| C-54 Ceramic and Mosaic Tile Contractor | Ceramic, porcelain, stone and mosaic tile installation. | 6,387 |
| C-55 Water Conditioning Contractor | Water softeners, filtration and treatment equipment. | 312 |
| C-57 Well Drilling Contractor | Drilling, deepening and repairing water wells. | 736 |
| C-60 Welding Contractor | Welding and cutting of metal on construction projects. | 1,119 |
| C-61 Limited Specialty | A catch-all for narrow trades, each tied to a D-subcategory such as window coverings, doors and gates, or pool maintenance. | 19,063 |
