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Employer classification manual

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Rate group table
Class A: Forest products
Class B: Mining and related industries
Class C: Other primary industries
Class D: Manufacturing
Class E: Transportation and storage
Class F: Retail and Wholesale trades
Class G: Construction
Class H: Government and Related services
Class I: Other services

Structural Steel Erection

Class G: Construction
Application Date
January 1, 2005
748: Form Work and Demolition
4227-000 : Structural Steel Erection
Document No.


Compulsory under Schedule 1


Business activities include the erection, maintenance, repair, or dismantling of pre-engineered structural steel and aluminum components. 

This category includes

  • metal aircraft hangars, pre-engineered
  • metal garages
  • metal office and factory buildings
  • metal roof trusses
  • pre-engineered metal buildings
  • structural components and shapes.

Also included is the supply of structural steel erection labour to any industry.


Special Operation activities are defined in the O. Reg. 175/98 and are classified as a business activity in its own right. A construction contract may require an employer to conduct Special Operation activities in conjunction with the contracted activity. Where the Special Operation activity accounts for

  • Less than 10 % of the total direct insurable earnings for the entire contract
  • Is considered by the WSIB to be integral to the main activity of the contract

it is not classified separately but instead is classified as part of the contract.

All business activities carried out underground for the mining industry are considered mining activities and must be classified in the appropriate Class B - Mining CU.

In the supply of labour industry, the agency supplying and paying the worker, not the employer to whom the worker is supplied, is responsible for covering the agency's workers under the Workplace Safety and Insurance Act.

These workers perform a variety of functions that are normally

  • part of the day-to-day operations, and
  • usually carried out by permanent staff

of the employer to whom they are supplied.

All workers supplied are compulsorily covered under Schedule 1 even if

  • the work activity they carry out, or
  • the business activity of the employer to whom they are supplied

is not covered according to the "Status" line of the relevant CU in the ECM. 

For information on classifying construction work by contract, see the section titled "Classification of Construction Activities" in The Classification Scheme, document 14-01-01, located in the Operational Policy Manual and in the Reference section of this Manual.

Cross reference

B-110-02, Gold Mines, Contracting.
B-113-02, Nickel Mines, Contracting.
B-119-16, Other Mines, Contracting.
D-375-04, Pre-engineered Metal Buildings.
G-707-02, Plumbing, Heating, and Air Conditioning, Installation.
G-711-02, Highways, Streets, and Small Bridges.
G-732-02, Large Bridge Construction.
G-737-01, Millwright and Rigging Work.
G-737-03, Other Trade Work.
G-764-03, Rough and Framing Carpentry.
I-929-01, Supply of Non-clerical Labour Operations.

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