When hiring an engineer to design or certify drawings, many people assume that "anyone with an engineering license can sign anything." In fact, engineering licenses come in several grades, and the law clearly sets how large a job each grade may take responsibility for. If an engineer signs work beyond their license grade, that drawing set will run into problems as soon as it is submitted for a building permit. This article summarizes the license grades, the scope of work for each grade under the current COE regulation, and how to check a license yourself.
How Many Grades of Engineering License Are There?
The professional engineering license (COE) under the Engineer Act B.E. 2542 (1999) has 4 grades: Associate Engineer, Professional Engineer, Senior Professional Engineer and Special Associate Engineer. Licenses are issued by the Council of Engineers Thailand (Council of Engineers, COE). Engineers start at the Associate grade after graduating and passing the exam, then move up grades based on experience and portfolio of work.
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| Level | How the grade is obtained | Design and calculation scope (civil) |
|---|---|---|
| Associate Engineer | Entry grade — graduate of a COE-accredited engineering program who has passed the exam | Limited-size work, e.g. buildings of no more than 4 storeys that are not public buildings |
| Professional Engineer | Promoted from Associate after accumulating the required experience and work, then passing the promotion exam | All types and all sizes (consulting limited to giving advice) |
| Senior Professional Engineer | Highest grade — promoted from Professional with senior-level experience and work | All types and all sizes, no restrictions |
| Special Associate Engineer | Issued to people with specialist knowledge of a specific type of work, without requiring an accredited degree | Specific work only, as stated on each holder's license |
The license grade is therefore the first thing to check when hiring a designer, not just "do they have a license?" — an Associate Engineer can take responsibility for an ordinary house, but public buildings or tall buildings must be handled by a Professional or Senior Professional Engineer only. For an overview of all design work, see Guide to RC structural design and civil engineering
What Can Each Grade Sign Under the 2023 Regulation?
The scope of work for each civil engineer grade is set in the Council of Engineers Regulation on Criteria and Qualifications of Controlled Engineering Practitioners of Each Grade, Civil Engineering Branch, B.E. 2566 (2023), which replaces the B.E. 2551 (2008) version. A Senior Professional Engineer may do all work of every size; a Professional Engineer may do all work of every size except consulting, where they may only give advice; and an Associate Engineer is clearly limited in the size of work. Key examples are in the table.
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| Type of work | Associate Engineer | Professional Engineer | Senior Professional Engineer |
|---|---|---|---|
| Project planning | Not permitted | All sizes | All sizes |
| Building design and calculation | No more than 4 storeys, or no more than 5 m per storey, and not a public building | All sizes | All sizes |
| Design of underground structures, retaining walls | Depth/height no more than 2.50 m | All sizes | All sizes |
| Bridge design | Not on the list of permitted work | All sizes | All sizes |
| Building construction supervision | No more than 8 storeys | All sizes | All sizes |
| Bridge construction supervision (span) | Pier spacing no more than 12 m | All sizes | All sizes |
| Inspection / operation and maintenance work | All sizes | All sizes | All sizes |
| Consulting | Not permitted | Advice only | All sizes |
A key point is that an Associate Engineer's scope for "design" and for "construction supervision" differs — they may design buildings of no more than 4 storeys but supervise construction of up to 8 storeys, while project planning and consulting are not permitted at all. Inspection work and operation and maintenance work, on the other hand, an Associate Engineer may do at any size. The Associate Engineer's full list covers many more categories, such as warehouses and silos up to 1,000 m³, dams and weirs up to 2.50 m, fluid storage tanks up to 500 m³, towers and chimneys up to 15 m, scaffolding and concrete formwork — see every item with explanations in Civil Associate Engineer scope: what can they sign? For the highest grade, read What is a Senior Professional Engineer and how does it differ from a Professional Engineer? and Which work requires a Senior Professional Engineer's signature?
The document an engineer must certify together with the drawings is the structural calculation report, which must also be signed by an engineer whose grade matches the size of the job. Read more in What is a structural calculation report?
How Does the Building Control Act Relate to License Grades?
The Building Control Act B.E. 2522 (1979) requires building permit applications to include drawings and calculations certified by a licensed engineer, while the Engineer Act B.E. 2542 (1999) requires that engineer to hold a license grade that covers the size of the job. The two laws work together — the first governs the building, the second governs the practitioner.
In practice, when a building permit application is submitted to the relevant authority, officials check both the drawings and the signatory. If the signing engineer's license grade does not cover the size of the job — for example, an Associate Engineer signing the design of a 6-storey building — the document set will not be approved and must go back to be checked and re-signed by an engineer of the correct grade, delaying the whole project. For the full submission process, see Building permit process
Engineers themselves also face direct risk. Practicing controlled engineering without a license, or working beyond the scope of one's grade, is an offense under the Engineer Act B.E. 2542 (1999), carrying both criminal penalties and ethics penalties from the Council of Engineers. Design work done properly within the license grade therefore protects both the project owner and the engineer. See our services at Civil engineering design
Where Can You Check an Engineer's License?
You can check for free on the Council of Engineers website, coe.or.th, by searching by full name or license number. The system shows the license grade, engineering branch and whether the license is still valid or has expired.
Before hiring a designer or having someone certify drawings, check 3 things: the license is still valid, the grade covers the size of your job, and the branch matches the work (building structures fall under civil engineering). The check takes only a few minutes but can prevent drawings from being rejected for the whole project.
This content summarizes key points of the COE Regulation, Civil Engineering Branch, B.E. 2566 (2023) for general understanding only. The actual scope of work has further details and conditions depending on the type of work. Practitioners and project owners should always check the full regulation and the current related laws.