For any construction project in Thailand, understanding the hierarchy of laws is crucial. This guide breaks down the legal structure, from the Constitution down to local ordinances, explaining how different laws like the Building Control Act and Urban Planning Act interact. Knowing which regulations take precedence is key to ensuring your design and construction process is smooth, compliant, and avoids costly delays or legal disputes from the start.

1. What to Know About the "Hierarchy of Laws"

For architects, engineers, or construction entrepreneurs, understanding the "Hierarchy of Laws" is a fundamental principle that helps ensure design and construction proceed smoothly and by various rules and regulations.

Understanding the legal hierarchy helps reduce the risk of designs that may conflict with laws at various levels, whether it be the Constitution, Acts, Ministerial Regulations, or local ordinances. Knowing which provision is superior and which law must be complied with first allows for precise design planning.

Furthermore, it saves both time and costs. When construction plans comply with the law from the outset, it reduces the chance of problems that could lead to design revisions or work stoppages. It also helps to clarify the powers and duties of various agencies. For instance, when applying for a permit or a waiver from a specific rule, you can proceed through the correct channels without unnecessary delays.

2. The Structure of the Thai Legal Hierarchy (7 Levels)

2.1 Constitution (รัฐธรรมนูญ)

Type of Law: Supreme Law Examples Related to Building Works: Principles of protecting housing rights. Remarks: The highest law of the land.

2.2 Act (พระราชบัญญัติ)

Type of Law: Same legal standing

‍Examples Related to Building Works:

• Building Control Act, B.E. 2522
• Urban Planning Act, B.E. 2562
• Enhancement and Conservation of National Environmental Quality Act, B.E. 2535

Remarks: All laws at this level have the same legal standing and must be complied with.

2.3 Emergency Decree (พระราชกำหนด)

Type of Law: Used in urgent cases

‍Examples Related to Building Works: Emergency Decree on Public Administration in Emergency Situations.

‍Remarks: Used in urgent or emergency situations.

2.4 Royal Decree (พระราชกฤษฎีกา)

Type of Law: Elaborates on an Act

‍Examples Related to Building Works:

• Defining building control areas.
• Specifying localities where laws are enforced.

‍Remarks: Provides additional details or specifications for an Act.

2.5 Ministerial Regulation (กฎกระทรวง)

Type of Law: Practical details

‍Examples Related to Building Works:

• Floor Area Ratio (FAR)/Open Space Ratio (OSR)
• Setbacks
• Building design for energy conservation
• Building forms and opening sizes.

‍Remarks: Defines practical details for the enforcement of the law.

2.6 Ministerial Announcement (ประกาศกระทรวง)

Type of Law: For notification/compliance

‍Examples Related to Building Works:

• Comprehensive Plan announcements.
• List of projects requiring an Environmental Impact Assessment (EIA).

‍Remarks: An announcement made to notify the public and ensure compliance.

2.7 Local Ordinance (ข้อบัญญัติท้องถิ่น)

Type of Law: Can be stricter than higher-level laws but not more lenient

‍Examples Related to Building Works:

• BMA Ordinance on Building Control.
• Various municipal ordinances.

‍Remarks: Local laws can set stricter standards than higher-level laws but cannot be more lenient.

Key Point: The three main pillars of law directly related to building works—the Building Control Act, the Urban Planning Act, and the Enhancement and Conservation of National Environmental Quality Act—are all at the Act level with equal authority. Therefore, relevant parties must comply with all three acts simultaneously; no single act is superior to the others.

3. Steps for Checking Laws and Regulations Before Design

3.1 Checking the City Plan: Defining the Type and Scope of Land Use

Checking the regulations of the urban planning law is the first and most crucial step before design. The use of every land plot is governed by this law, which acts as the "primary rulebook" for that area.

Key Information to Verify: You must check which "city plan color zone" the land is located in, as each color dictates different permitted types of land use.

• Example: Land in a Yellow Zone is designated as low-density residential land, suitable for building single-family or semi-detached houses. In contrast, a Red Zone is for commercial use, where office buildings or shopping centers can be built.

Governing Laws:

• Master Law: Urban Planning Act, B.E. 2562
• Area-Specific Law: The Ministerial Regulation on the Comprehensive City Plan for that specific province (e.g., Ministerial Regulation on the Comprehensive City Plan of Bangkok).

Impact on Design:

• Sets the project's direction: It determines what type of project can be developed on the land. If the regulations do not permit it, further design steps cannot proceed.
• Acts as crucial foundational data: The results of this check form the basis for considering subsequent regulations, such as Floor Area Ratio (FAR), Open Space Ratio (OSR), and setbacks.

3.2 Checking FAR and OSR: Defining the Size and Density of the Building

After knowing the land use type from the city plan in the first step, the next step is to check the physical regulations of the building, which are directly controlled through two important ratios: FAR and OSR.

3.2.1 Floor Area Ratio (FAR)

• Definition: This is the ratio used to control the total usable floor area of a building across all floors, relative to the size of the land plot. It determines the maximum size of a building that can be constructed on a given piece of land.
• Impact on Design: It determines the maximum usable floor area of the project. The higher the FAR value, the more usable floor area can be built.
• Calculation Example: A 100 sq.wah (equivalent to 400 sq.m.) plot of land in a zone where the FAR is set at 2.5:1 can have a building with a total usable floor area across all floors not exceeding 400 x 2.5 = 1,000 square meters.

3.2.2 Open Space Ratio (OSR)

• Definition: This is the regulation for the proportion of open, uncovered space (the open area around the building) that must exist, at a minimum, relative to the total building area that can be constructed.
• Impact on Design: To guarantee that the project will have sufficient open space for ventilation, lighting, water absorption, and green areas, which positively affects the project's overall environment.

Both FAR and OSR values are specified differently for each city plan color zone, concerning the "Ministerial Regulation on the Comprehensive City Plan" for each locality.

[Click here to learn more about calculating FAR and OSR]

3.3 Checking Building Setbacks: Defining the Buildable Area

A setback is the legally mandated distance a building must be recessed from property lines, roads, or public waterways, for safety, traffic, ventilation, and privacy. Checking setbacks is therefore crucial in determining the actual area on the land where construction can take place.

What to Check:

• Setback from public roads: This generally depends on the width of the public road in front of the land.
• Setback from adjacent property lines: There are distinctly different requirements for solid walls versus walls with openings (e.g., doors, windows, or light vents).

Governing Laws (The Hierarchy Principle): Checking setbacks is a clear example of applying the legal hierarchy, which must be considered in the following order:

1. Primary Law: The Building Control Act, B.E. 2522, and its key subordinate law, Ministerial Regulation No. 55 (B.E. 2543), which is the national standard.
2. Local Law: Ordinances of local administrative organizations, such as the Bangkok Metropolitan Administration Ordinance or regulations of various municipalities.

Key Enforcement Principle: You must always comply with the law that has stricter requirements. For example, if the Ministerial Regulation requires a 2-meter setback, but the local ordinance requires a 3-meter setback, the designer and project owner must adhere to the local requirement of 3 meters.

Impact on Design: Setbacks are the factor that clearly defines the "Building Envelope" on the land. This directly impacts the placement and shape of the building, as well as the allocation of open space around it for uses such as gardens, parking, or walkways.

[Click here to learn more about setbacks according to the Building Control Act and Urban Planning Law]

3.4 Checking Building Height: Controlling Vertical Dimension and the Urban Landscape

Building height is another key factor controlled by multiple laws simultaneously, for safety, the orderliness of the urban landscape, and respect for special area requirements. The check must, therefore, consider several legal sources.

Laws Related to Height Control:

1. Building Control Law: Generally references Ministerial Regulation No. 55 (B.E. 2543), which often sets the height to the width of the public road in front of the building, for safety and access for emergency services.
2. Urban Planning Law: The Ministerial Regulation on the Comprehensive City Plan for each locality may specify building heights for each color zone to control the physical characteristics and density of the city.
3. Other Specific Laws: In some areas, other laws may impose additional strict height controls, such as:
   
   • Aviation Law: Defines aviation safety zones around airports, which strictly limit the height of all structures in the vicinity.
   • Conservation Area Ordinances: In old town districts or near historical sites, height may be limited to preserve the environment and historical views.

Key Enforcement Principle: The designer must check all potentially relevant laws and must always adhere to the lowest (strictest) height requirement from any law as the design criterion.

Impact on Design: This height limitation directly affects decisions regarding the number of floors, the design of the roof shape (e.g., flat roof or gabled roof), and all components at the top of the building.

3.5 Checking Other Specific Regulations for the Bangkok Metropolitan Area

What you need to check: Additional restrictions or requirements that may be in effect in specific areas, such as limits on fence height, regulations on materials, or certain prohibitions.

Main Reference:

• Related Bangkok Metropolitan Administration Ordinances.

Impact on Design: Minor details that can affect components of the house, such as a prohibition on building a fence taller than 2 meters or regulations regarding parking spaces.

Always Remember (The Stricter Rule): In every step of the check, if multiple laws (e.g., a Ministerial Regulation and a BMA Ordinance) impose restrictions on the same issue, you must always adhere to the "stricter" requirement. For example, in step 3, if the Ministerial Regulation specifies a side setback of 1.5 meters but the BMA Ordinance specifies 2 meters, you must set back 2 meters to comply with the law.

4. Precautions for Architects and Developers

4.1 The 3 Main Pillars of Law Must All Be Complied With

Although these laws are at the Act level with equal authority, each covers a different dimension, all of which are important:

• Building Control Act: Focuses on structure, safety, and construction standards.
• Urban Planning Act: Defines land use, color zones, FAR/OSR.
• Enhancement and Conservation of National Environmental Quality Act: Pertains to EIA, pollution control, and drainage.

4.2 Local Laws May Be Stricter

Local ordinances, such as those of the Bangkok Metropolitan Administration, can impose stricter limitations than higher-level laws, but they cannot make them more lenient. Therefore, checking local ordinances is always essential.

4.3 Changes in Law Have Immediate Effect

When a law is amended or supplemented, projects that have not yet received a construction permit or are not yet completed must immediately comply with the new law.

5. Scenario Example: Uncle Somchai Wants to Extend His Kitchen

• Uncle Somchai: The owner of a townhouse in a municipality who wants to knock down the back wall and extend it into a closed Thai-style kitchen.
• What Uncle Somchai Thought: "It's just a small extension on my land. I probably don't need a permit. I'll just hire a contractor to do it."
• What Happened (Applying the Legal Hierarchy):
  
  • A Neighbor's Warning: The adjacent neighbor came over and said, "Uncle, you can't build the kitchen right up against the fence. There are laws controlling that."
  • Uncle Somchai Consults the Municipality: He went to the municipality's engineering division to be sure. An official explained:
    
    • The National Law (Ministerial Regulation No. 55) Specifies that if you build a solid wall (no windows), it must be at least 50 centimeters from the property line (the fence), and you need written consent from the neighbor.
    • The Local Law (Municipal Ordinance): However, Uncle Somchai's municipality has an ordinance for fire prevention and orderliness that sets a "stricter" rule: "All building extensions must be at least 1 meter from the property line."
• Uncle Somchai's Decision:
  
  • The municipal official advised that Uncle Somchai must follow the municipal ordinance because it is the stricter rule, even though the national law allows for 50 centimeters.
• Conclusion: Uncle Somchai had to go back and revise the plan with his contractor to ensure his new kitchen wall was 1 meter away from his neighbor's fence, by the local law, so he could apply for an extension permit correctly and avoid future problems.
• In this case, Uncle Somchai learned that:
  
  • Construction or extension, even on your property, must comply with the law.
  • Local laws (municipal ordinances) can have requirements that are "stricter" than national laws, and you must always follow the strictest rule.

6. Conclusion

Understanding the Hierarchy of Laws is a fundamental principle that will help you:

• Design and construct in a legally correct manner.
• Save time and costs from revisions.
• Understand the powers and duties of various agencies.
• Plan projects effectively.

Remember that the three main pillars of law (Building Control, Urban Planning, and Environment) are on the same level and must all be complied with, along with checking for local ordinances that may be stricter.

References

• The Constitution of the Kingdom of Thailand (รัฐธรรมนูญแห่งราชอาณาจักรไทย)
• Building Control Act, B.E. 2522 (พระราชบัญญัติควบคุมอาคาร พ.ศ. 2522)
• Urban Planning Act, B.E. 2562 (พระราชบัญญัติการผังเมือง พ.ศ. 2562)
• Enhancement and Conservation of National Environmental Quality Act, B.E. 2535 (พระราชบัญญัติส่งเสริมและรักษาคุณภาพสิ่งแวดล้อม พ.ศ. 2535)
• Ministerial Regulation No. 55 (B.E. 2543) issued under the Building Control Act, B.E. 2522 (กฎกระทรวง ฉบับที่ 55 (พ.ศ. 2543) ออกตามความในพระราชบัญญัติควบคุมอาคาร พ.ศ. 2522)
• Relevant Royal Decrees (พระราชกฤษฎีกา), Ministerial Regulations (กฎกระทรวง), Ministerial Announcements (ประกาศกระทรวง), and Local Ordinances (ข้อบัญญัติท้องถิ่น) such as the Bangkok Metropolitan Administration (BMA) Ordinances.