Prime Contractor Responsibilities in Alberta: A Practical Guide
If you work in construction, you've probably heard the term prime contractor.
You may even have been the prime contractor without realizing it.
In Alberta, every construction work site with two or more employers involved must have a prime contractor. The same requirement applies to oil and gas work sites and any other work site or class of work sites designated by an OHS Director.
That requirement comes directly from Section 10 of Alberta's Occupational Health and Safety Act.
The role exists for a practical reason. Once multiple employers are involved at the same work site, someone needs to coordinate health and safety between them.
That's the prime contractor.
What is a prime contractor?
A prime contractor coordinates, organizes and oversees health and safety activities when multiple employers are involved at a work site.
Under section 10 of Alberta's Occupational Health and Safety Act, the prime contractor must establish, as far as reasonably practicable, a system or process that ensures compliance with Alberta OHS legislation at the work site, including cooperation between employers and workers.
The prime contractor must also ensure that the owner and employers, suppliers and service providers at the work site are informed about existing or potential hazards that may affect workers or other people.
Alberta OHS summarizes the role as coordinating health and safety on a work site with two or more employers.
The important word there is coordinating.
The prime contractor does not replace every employer's health and safety responsibilities. Each employer still has obligations to its own workers and to other people who may be affected by its work.
The prime contractor provides the site-wide system that connects those responsibilities.
When is a prime contractor required in Alberta?
For construction, start with two questions:
Is this a construction work site?
Are two or more employers involved in the work?
If the answer to both is yes, a prime contractor is required under section 10(1) of the OHS Act.
This isn't limited to major commercial construction projects.
Alberta's OHS legislation defines construction broadly. Depending on the work being performed, construction can include activities such as building, demolition, repair, alteration, renovation, excavation, land clearing and other work associated with constructing or modifying a structure.
A relatively small project can therefore become a multi-employer construction work site.
The size of the project isn't the deciding factor.
The type of work and the employers involved are.
Do the employers have to be on site at the same time?
No.
This is one of the easiest parts of the requirement to misunderstand.
Alberta OHS specifically states in its Prime Contractor Role and Duties guidance that construction and oil and gas work sites with two or more employers require a prime contractor even when those employers don't work at the same time.
Consider a renovation.
Your company's employees perform demolition on Monday.
An electrical subcontractor comes in Tuesday.
A plumbing contractor performs its work on Wednesday.
Nobody is working shoulder-to-shoulder, but multiple employers are still involved at the construction site.
Staggering the schedule doesn't eliminate the prime contractor requirement.
Who becomes the prime contractor?
The person in control of the work site must designate the prime contractor in writing.
The prime contractor's name must also be posted in a conspicuous place at the work site.
Those aren't recommendations. They're requirements under sections 10(2) and 10(6) of the OHS Act.
If the person in control of a work site that requires a prime contractor fails to designate one, section 10(3) provides the fallback:
The person in control of the work site is deemed to be the prime contractor.
In other words, not designating someone doesn't leave the position vacant.
It can leave you with the position.
There is an exception to the designation provisions in sections 10(2) and 10(3) where the person in control of the work site occupies that site as their private dwelling. Residential projects can therefore require a little more care when determining how the legislation applies to the parties involved.
Is the general contractor automatically the prime contractor?
Not necessarily.
The terms are often used interchangeably in construction, but they aren't interchangeable under the legislation.
General contractor is generally a contractual or project-delivery role.
Prime contractor is a specific occupational health and safety function established under the Alberta OHS Act.
The general contractor may be designated as the prime contractor, and often is.
But the company everyone casually calls the GC isn't automatically the answer.
The better questions are:
Who controls the work site?
Is a prime contractor required?
Who has been designated in writing?
Who is responsible for fulfilling the prime contractor obligations?
On a multi-employer site, those distinctions matter.
What does a prime contractor actually have to do?
This is where the role becomes more than a name on the entrance sign.
Under section 10(7) of the OHS Act, the prime contractor must establish, as far as reasonably practicable, a system or process that ensures compliance with OHS legislation at the work site.
That system must include a process for cooperation between employers and workers regarding health and safety.
The prime contractor must also designate a person in writing to help ensure that cooperation occurs and to implement the system addressing the health and safety matters identified in the Act.
Under section 10(10), the prime contractor must ensure that the owner and employers, suppliers and service providers are informed about existing or potential work site hazards that may affect workers or other people.
What does that look like in the real world?
Depending on the work site, the system could include:
site safety rules
orientations
hazard communication
contractor prequalification
subcontractor requirements
inspections
incident and potentially serious incident reporting
safety meetings
emergency response processes
coordination of simultaneous or conflicting work
corrective actions
records showing that required activities actually occurred
A residential renovation and a major commercial construction project don't need identical systems.
But both need a system appropriate to their work.
Why does coordination matter?
Because employers don't operate inside bubbles.
Imagine one contractor performing hot work while another contractor is using a flammable substance nearby.
Each employer could have a perfectly reasonable safety program when viewed independently.
You can still have a serious problem.
The hazard exists because of the interaction between their activities.
The prime contractor function exists, in part, to deal with those intersections.
Someone needs to understand what's happening across the work site, make sure relevant hazard information is being shared and establish a process for coordinating activities between employers.
This is also consistent with Alberta's broader approach to multi-employer work sites. The Government of Alberta's Health and Safety Program guidance explains that employers on multi-employer work sites have obligations to coordinate their health and safety systems. Where a prime contractor exists, that contractor has specific duties to establish a system for cooperation and coordination.
A collection of individually compliant employers doesn't automatically create a coordinated work site.
Does the prime contractor become responsible for everyone's safety?
No.
This distinction is important.
Designating a prime contractor does not transfer every employer's OHS responsibilities to one company.
Employers continue to have obligations under section 3 of the OHS Act, including obligations relating to worker health and safety, training, supervision, hazard information and cooperation with other parties exercising duties under the legislation.
Supervisors have their own obligations.
Workers have their own obligations.
Owners, contracting employers, suppliers, and service providers can also have their own obligations.
The Government of Alberta describes this as the internal responsibility system, where every work site party is accountable for the health and safety responsibilities associated with its role.
You can see Alberta's summary of those responsibilities in Obligations of Work Site Parties.
The prime contractor adds coordination.
It doesn't erase everyone else.
What is a contracting employer, and how is that different?
This is another role contractors should understand.
Under section 8 of the OHS Act, a contracting employer that directs the activities of another employer involved in work at a work site must, as far as reasonably practicable, ensure that employer complies with OHS legislation at that work site.
A contracting employer must also ensure that relevant parties are informed about existing or potential work site hazards.
So if your company hires and directs subcontractors, you may have obligations as a contracting employer.
If the project also requires a prime contractor and your company has been designated as that prime contractor, you can have obligations under both functions.
Which brings us to an important part of the Act.
Can one company have multiple OHS roles?
Yes.
And this is where construction companies can accidentally oversimplify their responsibilities.
A company could potentially be an:
Employer, because it employs workers.
Contracting employer, because it directs other employers through contracts or agreements.
Prime contractor, because it has been designated to coordinate health and safety at a multi-employer work site.
It may have other functions as well depending on the project.
Section 12 of the OHS Act deals specifically with multiple obligations.
If a person has two or more functions under the Act at the same work site, that person must meet the obligations associated with each function.
Your job title doesn't determine the full extent of your responsibilities.
Your actual role in the work does.
What does a good prime contractor system look like?
A useful prime contractor system should answer some fairly basic questions.
Who is working here?
What work are they performing?
What hazards are they bringing to the site?
What hazards already exist?
Could one employer's work affect another?
Who is responsible for controlling those hazards?
How will changes be communicated?
What happens when someone identifies a deficiency?
How are incidents reported and investigated?
How will employers coordinate during an emergency?
And how can you demonstrate that any of this actually happened?
The last question matters.
Site rules aren't particularly useful if nobody knows about them.
An orientation process doesn't accomplish much if workers aren't actually oriented.
A corrective action isn't complete because somebody wrote it down.
The system needs to operate.
Prime contractor doesn't mean "safety police"
The objective isn't for the prime contractor to follow every subcontractor around the site looking for something wrong.
The role is broader than that.
A good prime contractor creates the structure that allows multiple employers to work safely together.
That means establishing expectations, sharing information, coordinating activities, identifying where responsibilities intersect and making sure problems don't disappear into the space between companies.
Because on a multi-employer work site, that's often where the interesting problems live.
Know your role before the work starts
Prime contractor responsibilities are considerably easier to manage when everyone understands their role before work begins.
If you're controlling a construction work site where multiple employers will be involved, establish early:
whether a prime contractor is required
who will be designated
what other OHS functions each party holds
how health and safety will be coordinated
how hazards and changes will be communicated
what records will demonstrate that the system is operating
The designation matters.
The system behind it matters more.
Putting a name on the wall satisfies one requirement.
It doesn't coordinate a work site.
Photo by Scott Blake on Unsplash
Alberta resources
For the legislation and government guidance referenced throughout this article:
Alberta Occupational Health and Safety Act: Part 1, General Obligations
Government of Alberta: Prime Contractor Role and Duties
Last reviewed: September 2026
This resource provides general information about occupational health and safety requirements in Alberta and is not legal advice. Responsibilities can vary depending on the work site, contractual relationships and the functions each party performs.
