General Building Contractors are the most common type of contractor, qualified to build residential and commercial structures. They typically serve as the primary contractor coordinating all aspects of building construction.

Electrical Contractors install, maintain, and repair electrical systems in residential, commercial, and industrial settings. They ensure all electrical work meets safety codes and regulations.

General Engineering Contractors handle major infrastructure projects including highways, bridges, dams, water systems, and other large-scale engineering works. They are qualified to perform any engineering construction project.

Painting and Decorating Contractors provide interior and exterior painting services, surface preparation, and decorative finishes for residential and commercial properties.

Plumbing Contractors install, repair, and maintain water supply systems, drainage systems, and related fixtures in residential, commercial, and industrial buildings.

Landscaping Contractors design, install, and maintain outdoor spaces including gardens, lawns, irrigation systems, and hardscape features.

HVAC (Heating, Ventilation, and Air Conditioning) Contractors install, maintain, and repair climate control systems for residential and commercial properties.

Roofing Contractors specialize in the installation, repair, and maintenance of roofing systems for residential, commercial, and industrial buildings.

Residential Remodeling Contractors specialize in making improvements to existing residential wood-frame structures.

Elevator Contractors install, maintain, and repair elevators, escalators, and related equipment.

Earthwork and Paving Contractors perform excavation, grading, and paving work.

Fencing Contractors install and repair fences, gates, and related security barriers.

Flooring Contractors install various types of floor coverings and flooring systems.

Fire Protection Contractors install and maintain fire sprinkler systems and related safety equipment.

Glazing Contractors install glass, windows, mirrors, and related glazing materials.

Insulation and Acoustical Contractors install insulation materials and sound control systems.

Building Moving/Demolition Contractors move structures and perform controlled demolition.

Asbestos Abatement Contractors safely remove asbestos and other hazardous materials.

Ornamental Metal Contractors fabricate and install decorative metalwork and structural metals.

Lock and Security Equipment Contractors install and maintain security systems and locks.

Masonry Contractors work with brick, stone, concrete block, and other masonry materials.

Construction Zone Traffic Control Contractors manage traffic safety in construction areas.

Parking and Highway Improvement Contractors work on roadways, parking lots, and related infrastructure.

Pipeline Contractors install and maintain pipelines for water, gas, oil, and other utilities.

Lathing and Plastering Contractors specialize in installing lath systems and applying plaster to walls and ceilings. They work with traditional plaster, stucco, and modern gypsum-based systems.

Refrigeration Contractors install and maintain commercial and industrial refrigeration systems.

Boiler and Steam Fitting Contractors install and maintain heating systems, boilers, and related equipment.

Sanitation System Contractors install and maintain septic systems and waste treatment facilities.

Sheet Metal Contractors fabricate and install sheet metal products and systems.

Sign Contractors design, fabricate, and install various types of signs and displays.

Solar Contractors install and maintain solar energy systems and related equipment.

General Manufactured Housing Contractors install and set up manufactured homes.

Tree Service Contractors provide tree care, removal, and related arboricultural services.

Framing and Rough Carpentry Contractors build the structural framework of buildings.

Reinforcing Steel Contractors place and install reinforcing steel (rebar) in concrete structures.

Structural Steel Contractors specialize in the fabrication, erection, and installation of structural steel frameworks for buildings, bridges, and other structures.

Swimming Pool Contractors build, install, and maintain swimming pools and spas.

Ceramic and Mosaic Tile Contractors install ceramic, porcelain, and mosaic tile surfaces.

Water Conditioning Contractors install and maintain water treatment and conditioning systems.

Water Well Drilling Contractors drill and install water wells and related equipment.

Cabinet and Finish Carpentry Contractors create custom cabinets, millwork, and detailed woodwork.

Welding Contractors provide specialized welding services for various construction and repair projects.

Limited Specialty Contractors perform specialized trades not covered by other classifications.

Low Voltage Systems Contractors install and maintain communication, security, and control systems.

Concrete Contractors pour, place, and finish concrete for various construction projects.

Drywall Contractors install, tape, and finish drywall and related wall systems.

Awning Contractors install and maintain awnings and shade structures.

Central Vacuum Systems Contractors install and maintain built-in vacuum systems.

Concrete Related Services Contractors provide specialized concrete services and repairs.

Drilling and Blasting Contractors perform specialized drilling and controlled blasting operations.

Elevated Floors Contractors install raised flooring systems and access floors.

Synthetic Products Contractors work with various synthetic materials and products.

Hardware, Locks and Safes Contractors install and maintain security hardware and safe systems.

Machinery and Pumps Contractors install and maintain industrial machinery and pump systems.

Metal Products Contractors fabricate and install various metal products and components.

Doors, Gates and Activating Devices Contractors install and maintain automated door and gate systems.

Paperhanging Contractors specialize in wallpaper installation and wall covering services.

Pile Driving Contractors install foundation piles and perform foundation stabilization work.

Pole Installation Contractors install and maintain utility poles, light poles, and similar structures.

Prefabricated Equipment Contractors install and maintain prefabricated structures and equipment.

Pool and Spa Maintenance Contractors provide ongoing maintenance and repair services for pools and spas.

Sand and Water Blasting Contractors provide surface cleaning and preparation services.

Scaffolding Contractors erect and maintain scaffolding systems for construction and maintenance work.

Service Station Equipment Contractors install and maintain gas station and automotive service equipment.

Siding and Decking Contractors install and maintain exterior siding and deck systems.

Non-Electrical Sign Installation Contractors install signs that do not require electrical connections.

Legacy Tree Service classification (converted to C-49 as of January 1, 2024).