Fast facts
| Trade code | 253A |
|---|---|
| Sector | Construction |
| Classification | Voluntary trade |
| Certifying exam | Required (O. Reg. 876/21, s. 3) |
| Apprentice to journeyperson ratio | Subject to a ratio (O. Reg. 876/21, s. 4) |
| Red Seal trade | Yes |
| Active apprentices in Ontario | 351 (reported in Ontario's apprenticeship dataset) |
| Approved sponsors | 5 |
| Certifying body | Skilled Trades Ontario |
Last verified August 20, 2026 against the sources listed below.
What does a heat and frost insulator do?
A Heat and Frost Insulator works with insulating material to prevent or reduce the passage of heat, cold, vapour, moisture, sound or fire.
Skilled Trades Ontario describes the work of this trade as follows:
- reads and interprets drawings and specifications to determine insulation requirements
- selects the amount and type of insulation to be installed
- measures and cuts insulating material to the required dimensions
- applies, installs, repairs and maintains insulating material
- installs fire-stopping insulation
- applies metal and plastic finishes
How long is the heat and frost insulator apprenticeship?
The in-school portion of this apprenticeship runs to 3 levels. Skilled Trades Ontario does not publish a total hour requirement for this trade on its trade page; confirm the current requirement in the trade's apprenticeship training standard before signing an agreement.
What do you study in school for the 253A?
The in-school portion covers, but is not limited to:
- use and maintenance of hand tools, power tools and shop equipment
- health, safety and asbestos regulations
- heat transmition – conduction, convection, radiation
- laws of thermodynamics – cryogenics
- thermal efficiency calculations
- blueprinting and drafting
- specialty insulation
- insulation on mechanical systems
- underground and spray-on insulation
Is heat and frost insulator a compulsory trade in Ontario?
No. Heat and Frost Insulator is a prescribed trade under section 1 of O. Reg. 876/21, but it is not on the compulsory list in section 2. That means you can legally work in this trade in Ontario without holding a Certificate of Qualification. Certification is voluntary and serves as formal proof of competency to employers and clients.
Voluntary classification only covers certification under the Building Opportunities in the Skilled Trades Act. Specific work within the trade can still require separate licences or permits under other Ontario statutes, so confirm the rules for the actual work being done. The 23 trades where certification is mandatory are on the compulsory trades list.
How do you become a heat and frost insulator in Ontario?
The apprenticeship pathway for this trade is administered by Skilled Trades Ontario under section 14 of the Building Opportunities in the Skilled Trades Act, 2021:
- Find a sponsor and register a training agreement. An employer or union sponsor takes you on and the training agreement is registered with the ministry.
- Complete the on the job and in school training. The skills are set out in the trade's Apprenticeship Training Standard, signed off by your sponsor as you demonstrate them, alongside levels of in school theory at a training delivery agent.
- Receive your Certificate of Apprenticeship. Skilled Trades Ontario issues it when the program is complete.
- Pass the certifying exam. This trade has a certifying exam under O. Reg. 876/21, s. 3. Passing it earns the Certificate of Qualification, the voluntary proof of qualification for this trade.
The exact training standard, current curriculum and program details are on the Skilled Trades Ontario page for Heat and Frost Insulator. On the job hour requirements vary by trade and are not published on this page yet; confirm them in the training standard before signing an agreement.
Is there an apprentice to journeyperson ratio for the 253A?
Yes. Heat and Frost Insulator is one of the 33 trades that section 4 of O. Reg. 876/21 makes subject to an apprentice to journeyperson ratio. The regulation establishes that a ratio applies, but the numeric ratio itself is not stated in section 4. Confirm the current ratio with Skilled Trades Ontario before registering an additional apprentice, because it limits how many apprentices a sponsor may train at once.
Is the 253A a Red Seal trade?
Yes. Heat and Frost Insulator participates in the Interprovincial Red Seal Program, the national standard for the trade across Canada, stewarded by the Canadian Council of Directors of Apprenticeship. A Red Seal endorsement on an Ontario Certificate of Qualification means the qualification is recognized in other provinces and territories without re examination, which matters for workers moving between provinces and for employers hiring from outside Ontario.
The Red Seal exam for this trade, written under the national title Insulator (Heat and Frost), has 130 multiple-choice questions, each with four possible answers and exactly one correct answer.
How the 130 questions are distributed
| Major Work Activity | Questions |
|---|---|
| A. Performs routine occupational skills | 16 |
| B. Performs industrial applications | 40 |
| C. Performs commercial applications | 39 |
| D. Performs applications common to industrial and commercial systems | 15 |
| E. Performs specialized applications | 12 |
| F. Performs asbestos , lead and mould abatement | 8 |
By question type, this trade's exam runs 15 to 25% knowledge and recall, 65 to 75% procedural and application, and 5 to 15% critical thinking.
Already experienced? The Trade Equivalency Assessment
Workers with experience from outside Ontario's apprenticeship system, or from another country, can apply for a Trade Equivalency Assessment instead of starting an apprenticeship. Approval requires verifiable evidence of competency in the trade's Training Standard and experience at least equal to the trade's total training time; if approved, you challenge the certifying exam directly. The assessment costs $235 plus HST, and a reassessment with new evidence costs $100 plus HST, per Skilled Trades Ontario's Trade Equivalency Assessment page.
Certification is not the only paperwork
A Certificate of Qualification covers the person. Running a business in the trade carries its own obligations: many Ontario municipalities require a contractor licence on top of personal certification, and construction employers must complete WSIB registration before work begins. Both are indexed on our sister site: municipal contractor licensing requirements by city and WSIB Form 1000, registration of constructors and employers, on Ontario Trade Registry.
What does a heat and frost insulator earn in Ontario?
| Median wage | $35.00 per hour |
|---|---|
| Low | $22.00 |
| High | $48.88 |
| Occupation measured | Insulators (NOC 72321) |
| Reference period | 2023-2024 |
Published by Employment and Social Development Canada through Job Bank, for Ontario as a whole. Read it as the pay range for the occupational group this trade belongs to, not a guaranteed rate: one NOC code can cover more than one trade, and wages vary by region, employer and experience.
A note on this trade's Red Seal status
Two official sources disagree here. red-seal.ca lists Ontario among the provinces that designate this trade Red Seal, while Ontario's own apprenticeship dataset does not flag it as a Red Seal trade. This page follows red-seal.ca, which is maintained by the Canadian Council of Directors of Apprenticeship, the body that runs the Red Seal Program. Confirm your own position with Skilled Trades Ontario before relying on it for interprovincial recognition.
Is the 253A recognised outside Ontario?
This trade has been part of the Interprovincial Red Seal Program since 1991. 13 of Canada's 13 provinces and territories designate it Red Seal: AB, BC, MB, NB, NL, NS, NT, NU, ON, PE, QC, SK, YT, Ontario among them. Its National Occupational Classification code is 72321, which is how federal labour market data refers to this occupation.
Where can you train as a heat and frost insulator in Ontario?
| Private training providers | 1 |
|---|---|
| Approved sponsors | 5 employers registered to train apprentices |
| Apprentices in training | 351 |
Counts are from Ontario's published apprenticeships dataset. A sponsor is the employer or union that registers and trains the apprentice; you need one before an apprenticeship can start.
How dangerous is construction work in Ontario?
Ontario does not publish injury figures per trade, only by sector. In 2024 the Ministry of Labour recorded 18 worker fatalities and 442 critical injuries under the construction health and safety program. See the ten-year counts and what they leave out.
Related Ontario trades
Other construction sector trades with certification records on this registry:
Official verification sources
- RegulationO. Reg. 876/21, Prescribed Trades and Related Matters (e-Laws)
- Certifying bodySkilled Trades Ontario: Heat and Frost Insulator
- ActBuilding Opportunities in the Skilled Trades Act, 2021 (e-Laws)
- WagesJob Bank wage data, Employment and Social Development Canada
- Red Seal profilered-seal.ca: Heat and Frost Insulator trade profile
- Participation dataOntario open data: Apprenticeships dataset
Classification, exam requirement and ratio status on this page are read directly from O. Reg. 876/21 as consolidated on e-Laws, not from secondary summaries. Facts not yet verified against a primary source are marked as not published rather than estimated.