The construction sector

Construction is a dynamic industry with workplaces and workforces that change constantly. The construction sector covers both large and small firms and includes unionized and non-unionized workplaces. Even though some establishments do not maintain employee payrolls, they may have workforces which may consist of contracted workers, part-time employees, family members or business owners.

Most of the construction contractors in Ontario are small- to mid-size employers. Almost 90 per cent of construction employers have fewer than eight employees. About one per cent employ more than 100 workers;footnote 1 however, these personnel are often deployed across several projects.

Through the course of a typical project, 10 or more different employers may be involved and there may be as many as 10 different trades and trade unions on site. These multiple-employer and multiple-union workplaces are quite different from those in other industries. Although “construction” may describe all of the work, the individual activities are quite diverse.

The Occupational Health and Safety Act (OHSA) defines “construction” as including erection, alteration, repair, dismantling, demolition, structural maintenance, painting, land clearing, earth moving, grading, excavating, trenching, digging, boring, drilling, blasting or concreting, the installation of any machinery or plant, and any work or undertaking in connection with a project (excluding any work or undertaking underground in a mine). “Project” is also defined in section 1 of the act.

Although Ontario’s construction industry is one of the safest in the world, there is a high potential for injury, given the nature and conditions of the work. The Ministry of Labour continues to work actively with its health and safety partners and external stakeholders to control and, where possible, eliminate the top hazards in each sector and to promote compliance and the development of a strong health and safety culture in the workplace.

Ontario’s diverse, complex construction industry is made up of a number of primary sectors, each with subsectors.

Asbestos abatement operations

Asbestos abatement operations include removal operations involving the repair, alteration, renovation, demolition and maintenance of buildings and the repair, alteration, maintenance or demolition of machinery, equipment, aircraft, ships, locomotives, railway cars and vehicles. Asbestos abatement workers, maintenance workers, construction trades, and other workers engaged in “asbestos operations” are exposed to asbestos during the removal or disturbance of asbestos-containing-material in buildings or structures like boilers, pipes and other mechanical equipment.

For the purposes of enforcement of Ontario Regulation 278/05 – Asbestos on Construction Projects and in Buildings and Repair Operations, operations that may expose a worker to asbestos are classified as Type 1, Type 2 and Type 3 operations. As the risk increases from Type 1 to Type 2 to Type 3 operations, the protective measures and procedures prescribed in the regulation become increasingly stringent.

Industrial, commercial and institutional (ICI)

The ICI sector comprises high- and low-rise industrial, commercial and institutional building projects, and above-ground mining plants.


Made up of both high-rise (i.e., apartment and other multiple housing) and low-rise residential projects, including “in-fill” housing, single homes, multiple housing (e.g., townhouses) and renovations and additions, the sector is characterized by multiple contractors and independent operators.


This sector includes heavy civil works or infrastructure comprising highway and road construction, both new construction and rehabilitation of existing highways and roads, bridge work and asphalt paving operations.


Mostly sewer and water main construction, trenching, excavations, caisson and cofferdam construction, shaft construction, tunneling, and subway and railway construction.


Includes the construction of underground utilities (gas and oil pipelines, hydro-electrical power, telephone, cable) and above-ground power and distribution lines, transmission and electrical towers.

Window cleaning

Consists of window cleaning services for buildings and the cleaning of windows where a worker may fall a vertical distance of three metres or more.

Other construction

This covers projects not captured in other sectors such as silo construction, moving buildings and structures and other construction not elsewhere classified.


A “diving operation” means work performed under water by divers or work performed on the surface in support of divers. Diving operations include underwater inspection, investigation, excavation, construction, alteration, repair or maintenance of equipment, machinery, structures or ships, scientific research, aquaculture support, emergency services, disposal of unexploded devices, environmental (abatement of spills) and the salvage of sunken property.


  • footnote[1] Back to paragraph Government of Canada - Number of establishments in Canada by type and province/territory: December 2014 Construction (NAICS 23)