How to Start in Canada

How to Become a Boilermaker Apprentice in Ontario

Ontario's Construction Boilermaker apprenticeship, trade code 428A: Grade 10 entry, three levels, 5,880 hours on the job plus 720 hours of in-school training, voluntary status, and the certifying exam with a Red Seal endorsement.

Written October 30, 2026 · 8 min read

Applies in: Ontario

The path in one paragraph

In Ontario, a boilermaker apprentice registers under the trade name Construction Boilermaker, code 428A. Find a boiler, tank, or pressure vessel contractor or shop willing to sponsor you, register the apprenticeship with Skilled Trades Ontario, and work through three levels that combine 5,880 hours on the job with 720 hours of in-school training, 6,600 hours in total. At the end, the trade has a certifying exam, and passing it earns a Certificate of Qualification with the Red Seal endorsement under the name Boilermaker, recognized across Canada.

First: the name, then the voluntary-trade reality

The name causes the first confusion. Job postings say boilermaker. The Ontario system says Construction Boilermaker 428A. They are the same apprenticeship. Skilled Trades Ontario lists Construction Boilermaker 428A as a Red Seal trade, and its trade page ties the trade to the national title Boilermaker. Use code 428A whenever a form asks for the trade, and expect Boilermaker on the national exam material.

The second point matters just as much. Construction Boilermaker is a non-compulsory trade in Ontario. Nobody needs a licence or certificate to do boilermaker work in this province, and you can work in the trade without ever registering. The apprenticeship is not permission to work. It is structured training, a logbook of signed-off skills, a Certificate of Apprenticeship, and the path to the certifying exam and the Red Seal endorsement. Do not assume the Ontario rule travels with you. Job Bank records boilermaker certification as compulsory in Nova Scotia, Quebec, and Alberta. If Alberta or Quebec is in your plans, the certification requirement there is a different conversation.

What the trade covers, in Skilled Trades Ontario's own description, is building, installing, erecting, testing, maintaining, and repairing all types of boilers, tanks, and pressure vessels, and performing structural and plate work on dust, air, gas, steam, oil, water, and other liquid-tight pressure vessels. A construction boilermaker works from fabrication drawings to fabricate components from steel or other materials, uses metal forming machines such as rotary shears, punch presses, and bending rolls, tests boiler systems for leaks and defects, and attaches rigging and works with hoisting devices to lift components into place. Pressure is the fact that separates this trade from general steel work: the vessels hold liquids and gases under pressure, and a failed test is not a cosmetic problem.

Step 1: Get sponsored and register with Skilled Trades Ontario

The sponsor comes first. Skilled Trades Ontario is clear that an apprenticeship begins when you sign a Training Agreement with a sponsor and register it, and that finding a sponsor is the key first step. A sponsor can be an individual employer, such as a boiler contractor, a tank and vessel fabrication shop, or an industrial maintenance employer, or a group of employers, such as a union or consortium.

The application steps, from Skilled Trades Ontario's start-an-apprenticeship page, are:

  1. Confirm you qualify. You must be at least 16 years old, have legal permission to work in Canada, meet the education requirements for the trade, and have a sponsor in Ontario. For Construction Boilermaker 428A, the chart entry grade is Grade 10.
  2. Find the sponsor. Ask at school about the Ontario Youth Apprenticeship Program if you are in high school, check college career centres, post a resume on job sites, contact Employment Ontario, talk to unions and trade groups, and approach local boiler and fabrication companies directly. Shop-helper work with a boilermaker crew is a common first step toward sponsorship, and it is where most apprentices learn whether they like the rigging, the welding, and the shutdown pace.
  3. Apply. If you are 18 or older, apply online through the Skilled Trades Ontario Portal. If you are 16 or 17, or unable to apply online, download the Application for Apprenticeship Training, complete and sign it, have your sponsor sign it, and submit it by email or mail to Skilled Trades Ontario. Skilled Trades Ontario lists its phone lines as 647-847-3000 and toll-free in Ontario at 1-855-299-0028.
  4. Sign and register the Training Agreement. Once approved, you and your sponsor sign the agreement. You can access the Registered Training Agreement through your portal account, or Skilled Trades Ontario mails a copy if you have no portal account. You also receive a Registered Apprentice Wallet Card to carry while you work.
  5. Download the Apprenticeship Training Standard Logbook. It lists the skills and tasks to master, and your sponsor or trainer signs off each skill once you demonstrate it.

Step 2: Work the three levels

The program totals 6,600 hours: 5,880 hours of on-the-job training and 720 hours of in-school training across three levels. The apprenticeship programs chart marks the trade as hours-based, which means you must complete the on-the-job training for the entire duration of the prescribed hours, and hours-based trades carry a ratio of one journeyperson to one apprentice. About 80 per cent of an Ontario apprenticeship is paid work on the job and about 20 per cent is classroom learning, according to Skilled Trades Ontario.

The rhythm is work, then a block of in-school training, then work again. The in-school curriculum, as Skilled Trades Ontario lists it for this trade, runs across trade practices such as health and safety documentation, plant systems and ancillary components, rigging and hoisting, crafting and drawing interpretation, cutting and welding procedures, applied trade calculations and mathematics, and metallurgy. Depending on the training delivery agency, in-school training may be block release, day release, part-time, or alternative delivery. Attend when invited through the training system, keep your logbook current, and make sure your recorded hours match what your sponsor reports.

Step 3: Write the certifying exam and earn the Red Seal

Construction Boilermaker 428A has a certifying exam. Skilled Trades Ontario issues a Certificate of Apprenticeship when you complete the apprenticeship program, and a Certificate of Qualification when you pass the certifying exam. Because the trade is part of the Interprovincial Red Seal Program under the title Boilermaker, passing the exam also carries the Red Seal endorsement, which is the credential recognized in every province and territory.

Experienced boilermakers who never registered have a parallel door. The Trade Equivalency Assessment lets experienced tradespeople document equivalent qualifications or experience and seek the Certificate of Qualification without completing the apprenticeship. The application guide requires verifiable evidence of competency against the Training Standard and experience at least equal to the required training time, 6,600 hours for this trade, supported by work experience verifications from references who know the work first-hand.

What not to do

Do not start work assuming the Ontario voluntary status applies everywhere in Canada. Alberta, Quebec, and Nova Scotia treat boilermaker certification as compulsory, so check the destination province before you move for work. Do not confuse this trade with Welder, which is the welding trade on its own, or with Steamfitter, which installs piping systems rather than building and repairing the vessels themselves. Do not let months of site work go unrecorded. In an hours-based trade, unrecorded hours are hours you may have to work again, so keep the logbook signed and the hours submitted. And do not pay for a course that promises the certificate on its own. The certificate comes through Skilled Trades Ontario on completion of the program and the certifying exam, not through a private training provider alone.

Related guides:

The Ontario construction boilermaker apprenticeship, step by step

  1. Find a sponsoring employerA boiler, tank, or pressure vessel contractor or shop willing to train you
  2. Register with Skilled Trades OntarioSTO Portal if you are 18 or older, paper form if you are 16 or 17; approval brings a Training Agreement
  3. Work the three levels5,880 hours on the job plus 720 hours of in-school training, 6,600 hours in total, hours-based
  4. Write the certifying examThe trade has a certifying exam and a Red Seal endorsement on passing

Questions people ask

What is the Ontario boilermaker trade officially called, and what code goes on the forms?

Construction Boilermaker, trade code 428A. That is the Ontario trade name in the Skilled Trades Ontario apprenticeship programs chart. The national occupation name is Boilermaker, National Occupational Classification 72103, and the Red Seal title is Boilermaker. When a form asks for the trade, put down 428A. It separates this trade from Welder and Steamfitter, which are different Ontario trades that also work with pipe and pressure equipment.

How long does a construction boilermaker apprenticeship take in Ontario?

The program is 6,600 hours: 5,880 hours of on-the-job work experience and 720 hours of in-school training, delivered across three levels. Skilled Trades Ontario describes that total as approximately four years. The apprenticeship programs chart marks the trade as hours-based, which means you complete the full prescribed on-the-job hours rather than progressing on competency sign-off alone. Job Bank describes the occupation route as a three- to four-year apprenticeship program, or a combination of over four years of work experience in the trade and some high school, college, or industry courses in boilermaking. The hours are the fixed part; the calendar time follows how steadily the work comes.

Is construction boilermaker a compulsory trade in Ontario?

No. Construction Boilermaker 428A is non-compulsory in Ontario. You do not need to be a registered apprentice or a certificate holder to do boilermaker work in this province, though registration is still how you get the structured training, the Certificate of Apprenticeship, and the certifying exam. Skilled Trades Ontario states that because the trade is non-compulsory, the Certificate of Qualification does not have to be renewed, and people practising the trade do not appear on the Skilled Trades Ontario Public Register. Job Bank records the national position for boilermakers the same way: trade certification is compulsory in Nova Scotia, Quebec, and Alberta, and available, but voluntary, in all other provinces. Do not assume the Ontario rule travels with you to Alberta or Quebec.

What education do you need to start this apprenticeship in Ontario?

Grade 10 is the academic entry grade listed in the Skilled Trades Ontario apprenticeship programs chart for Construction Boilermaker 428A. Skilled Trades Ontario also requires apprentices to be at least 16 years old, to have legal permission to work in Canada, and to have a sponsor in Ontario. Job Bank describes completion of secondary school as usually required for the occupation nationally, so treat Grade 10 as the floor, not the competitive standard: a diploma, and comfort with applied trade calculations, metallurgy, and reading fabrication drawings, will matter to a sponsor deciding whether to take you on. The in-school training runs on trade calculations and drawing interpretation, so math and technical reading are worth arriving with.

How do you register as a construction boilermaker apprentice with Skilled Trades Ontario?

First find a sponsor, an employer or group sponsor responsible for your training. Then apply: if you are 18 or older, apply online through the Skilled Trades Ontario Portal; if you are 16 or 17, or you cannot apply online, complete the paper Application for Apprenticeship Training, signed by you, a parent or guardian if you are under 18, and your sponsor, and submit it to Skilled Trades Ontario. Once approved, you and your sponsor sign a Training Agreement, which registers you as an apprentice, and you receive a Registered Apprentice Wallet Card.

Can experienced boilermakers challenge the certification without apprenticing?

Yes, through the Trade Equivalency Assessment. It exists for tradespeople who never completed an Ontario apprenticeship but hold equivalent qualifications or experience and want an Ontario Certificate of Qualification. The bar is documented proof: competency against the Training Standard and experience at least equal to the required training time, supported by work experience verifications from references who saw the work. Check the current Trade Qualifier application guide before relying on that route, because the evidence bar is documentary.

Keep going

Sources

Where a figure could not be verified on a Skilled Trades Ontario or Job Bank page at the time of writing — any examination fee, any wage figure, and the calendar length of the in-school training blocks — this guide says so and points to the Skilled Trades Ontario trade page instead of carrying a secondary source's figure. Check that page before you pay anything or plan around a date.

Get new guides by email

One short email when a new Canadian startup guide publishes. No spam — unsubscribe anytime.

We use your address only for the newsletter. Privacy policy.