Construction Law in Thailand: Permits, Liability, and Disputes

Construction law in Thailand sits on two anchor statutes — the Building Control Act B.E. 2522 (1979), which sets the technical and safety standards for structures, and the Town Planning Act B.E. 2562 (2019), which controls what can be built where — layered with rules on environmental review, contractor liability, workplace safety, property tax, and foreign participation. Developers who miss any layer risk fines, demolition orders, and years of litigation. The core statutes apply nationwide, but municipalities set their own zoning maps and can adjust some rates within statutory bands.

Building Standards and Setbacks

The Building Control Act authorizes the Ministry of Interior to issue ministerial regulations covering structural integrity, fire safety, ventilation, and sanitation. Two size classifications trigger extra scrutiny. A “high-rise building” is any structure 23 meters or taller measured from ground level to the roof deck. An “extra-large building” has a combined floor area of 10,000 square meters or more across all stories.¹ Both face stricter fire safety obligations, mandated escape routes, fire-resistant materials, and additional structural review before permits issue.

Ministerial regulations also prescribe how far a building must sit from property boundaries and public roads. Row houses and townhouses must maintain at least a 2-meter gap from a neighbor’s land, with a 3-meter open space in front and 2 meters at the rear. Buildings taller than two stories or 8 meters near a public road must set the building line back further, calculated from the road’s width. For roads under 10 meters wide, the building line must sit at least 6 meters from the road’s center; for roads of 20 meters or more, the minimum is 2 meters from the road boundary.²

These setbacks exist to ensure light, ventilation, and fire access. A violation can lead to a court order requiring modification or demolition of the offending portion, so confirm the exact requirements for your building type before pouring any foundation.

Zoning and Land Use

The Town Planning Act divides land into color-coded zones that dictate what can be built where.³ There are 13 categories in total. The ones developers meet most often are:

Yellow: low-density residential, with size and height limits meant to preserve neighborhood character.
Orange: medium-density residential.
Brown: high-density residential.
Red: commercial center zones for offices, retail, and mixed-use.
Purple: industrial zones for factories and heavy operations.
Lilac: warehouse zones.
Green: rural and agricultural land.
Blue: government institutions, utilities, and civic amenities.

Before you buy a plot, verify that your intended use matches the current zoning. Building outside a zone’s permitted use means automatic denial of the construction permit. Zoning maps are available through the local administrative office, and checking early avoids designing a project that cannot get approved.

Getting a Construction Permit

Every new construction, major modification, or demolition project requires a building permit from the Local Administrative Organization (the OrBorTor) in the district where the land sits.

What Goes in the Application

The application must include proof of land ownership, typically a Chanote title deed; architectural blueprints and structural calculations signed by a licensed Thai architect and a professional engineer registered with their respective national councils; copies of those professionals’ licenses; and, if the applicant is not the landowner, written consent from the owner. The blueprints have to be cross-referenced with the title deed so the building footprint stays within legal boundaries and satisfies the setback rules. Inconsistent documents get rejected at initial screening.⁴

Timeline and Fees

Under Section 25 of the Building Control Act, the local authority must approve or deny the application within 45 days of receipt. If review cannot finish in that window, the authority may extend up to two additional times of 45 days each, but must notify the applicant in writing before the original deadline expires.¹ A straightforward application could therefore take up to 135 days in the worst case, though most standard residential projects clear review faster.

Inspection fees are based on total floor area. Standard buildings of three stories or fewer are charged 2 baht per square meter per floor; buildings taller than three stories or 15 meters are charged 4 baht per square meter per floor. The fees are modest, but payment is a prerequisite for final issuance.

Penalties for Building Without a Permit

Starting construction without an approved permit carries criminal exposure: up to three months’ imprisonment, a fine of up to 60,000 baht, or both.⁴ For commercial, industrial, or educational buildings, the penalty escalates to imprisonment of up to two years or a fine of up to ten times the standard penalty. These are per-offense penalties, so continuing to build after being cited compounds exposure.

Permit Validity

An approved permit is valid for one year. If construction is delayed, it can be renewed annually for up to three additional years. Letting it lapse and continuing to build puts you back in “no permit” penalty territory, so track the expiration date.

When an Environmental Impact Assessment Is Required

Certain projects must obtain an approved Environmental Impact Assessment (EIA) before any building permit can issue. The Enhancement and Conservation of the National Environmental Quality Act B.E. 2535 authorizes the Minister of Natural Resources to designate the categories and sizes of projects that need one.⁵

Common triggers for construction include condominium developments with 80 or more units, projects with a combined usable floor area of 4,000 square meters or more, and buildings in environmentally sensitive areas near waterways, national parks, or historical sites. Projects that may severely affect community health face the more rigorous Environment and Health Impact Assessment (EHIA).

The EIA must be prepared by a consultant registered with the Office of Natural Resources and Environmental Policy and Planning (ONEP), and public participation is required at least twice during preparation. ONEP has 30 days to review the report and forward it with preliminary comments to an Expert Review Committee (ERC). The ERC then has 45 days to approve or reject. If the ERC fails to act within its 45 days, the EIA is deemed approved. Only after approval can the permitting agency issue the building permit. This process adds roughly three to six months to the pre-construction timeline for projects that trigger it.

Contractor Liability Under the Civil and Commercial Code

The private relationship between project owner (the “employer” in Thai law) and contractor sits under the Civil and Commercial Code’s Hire of Work provisions, Sections 587 through 607. These rules fill gaps a written contract might leave and apply even where the contract is silent.

Defect Liability Periods

Section 600 sets the default liability windows. A contractor is responsible for defects appearing within five years of delivery for any structure built on land, except wooden buildings. For all other work, the period is one year after delivery.⁶ These periods apply unless the contract specifies otherwise. If a contractor conceals a defect, the time limits do not apply and liability continues indefinitely.

Section 598 adds an important nuance: once the employer accepts the completed work, the contractor is no longer liable for defects that were discoverable at the time of acceptance. The exception is hidden defects or ones the contractor deliberately concealed.⁶ That makes the handover inspection critical. Accepting delivery without a thorough inspection effectively waives claims for visible problems.

Risk, Retention, and Insurance

Until the employer accepts delivery, the risk of loss or damage to the work generally stays with the contractor. Section 599 allows the employer to withhold payment if the work is defective or delivery is late, unless the contractor provides adequate security.⁶ Most construction contracts include a retention clause of 5% to 10% of contract price held for a set period after handover, functioning as security for defects discovered after acceptance. The Code does not mandate a specific percentage, but the clause is standard.

Contractor All Risk (CAR) insurance is not legally required, but is routinely mandated by contract. CAR policies cover physical damage to the works, third-party liability, and sometimes contractor equipment. Lenders and employers will insist on it for any project of meaningful size.

Worker Safety and Social Security

The Occupational Safety, Health and Environment Act B.E. 2554 (2011) is the primary workplace safety law, and construction sites get particular attention because of the industry’s injury rate. Employers must conduct written risk assessments before work starts, provide safety training, and appoint qualified safety officers on site.

Personal protective equipment is mandatory: helmets, safety footwear, high-visibility clothing, and eye protection, plus a full-body harness for anyone working at height. If a worker is found without required PPE during an inspection, the penalty falls on the employer.

Ministerial regulations govern heavy equipment. Cranes with a safe working load above three tonnes must be inspected by a licensed engineer at least every three months. Scaffolding needs daily visual checks and a formal inspection after any modification or adverse weather. Wire ropes, slings, and shackles must be checked before each use and replaced at the first sign of wear.

Employers must also register construction workers with the Social Security Fund. As of January 2026, employers and employees each contribute 5% of monthly wages, with a wage ceiling of 17,500 baht per month, capping the maximum monthly contribution at 875 baht per side.⁷ The ceiling was raised from 15,000 baht in 2025, so employers who have not updated payroll systems will be under-contributing.

Land and Building Tax

The Land and Building Tax Act B.E. 2562 replaced the older house and land tax with a value-based system. Anyone owning property on January 1 of the tax year owes tax at rates that turn on use:

Agricultural land: 0.01% to 0.10% of assessed value.
Owner-occupied residence: first 50 million baht of combined land and building value is exempt; rates above that range from 0.02% to 0.10%.
Other residential property (second homes, rental units): 0.02% to 0.10%.
Commercial and industrial property: 0.30%, with Cabinet authority to raise to 0.70%.
Vacant or underutilized land: 0.30%, increasing by 0.30 percentage points every three years, capped at 3%.

Assessment notices arrive in February and payment is due by the last business day of April. Local councils can set rates anywhere within the statutory bands, so actual rates vary by jurisdiction. A company that owns property is taxed at the commercial rate even if a director lives there rent-free, because the owner-occupied exemption applies only to natural persons. The escalating rate on vacant land matters for developers sitting on undeveloped plots: holding land without building for more than three years triggers automatic rate increases.

Foreign Participation Rules

The Foreign Business Act B.E. 2542 (1999) places construction on List Three of restricted businesses, so foreign entities need a Foreign Business License (FBL) before operating. A company is considered “foreign” if persons or entities from outside Thailand hold at least half of its capital shares.⁸ To avoid FBL requirements, Thai nationals must hold more than 50% of the equity.

One narrow exception covers infrastructure construction: projects that serve the public in transportation or other basic services, require specialized technology, and involve foreign capital of at least 500 million baht are carved out of the restriction.⁹ Outside that exception, most foreign developers operate through joint ventures with Thai majority partners.

Foreign Business License Process

Applications go to the Ministry of Commerce. A presiding official screens documents before formally accepting the application; this preliminary stage has no statutory time limit. Once accepted, the Foreign Business Committee has 60 days to rule, evaluating national security, economic impact, technology transfer, and environmental effects.¹⁰

An alternative runs through the Board of Investment (BOI). Foreign companies that receive BOI promotion for a qualifying investment can notify the Director-General of the Commercial Registration Department and obtain a certificate instead of going through the full FBL process.¹⁰ It is significantly faster but requires the project to qualify under a BOI promoted activity category.

Professional Licensing

Even inside a properly structured joint venture, foreign architects and engineers face separate barriers. The Architect Act B.E. 2543 and Ministry of Labor regulations restrict the architectural profession to Thai nationals. Amendments in B.E. 2566 created a framework for architects from ASEAN member countries to register in Thailand under mutual recognition arrangements, but the process is cumbersome and the number practicing under it remains very small. As a practical matter, all architectural and structural engineering drawings submitted with a permit application must be signed by Thai-licensed professionals.

Condominium Foreign Ownership Cap

For developers building condominiums, a separate restriction applies at the unit level. Under the Condominium Act, foreign nationals may own units totaling no more than 49% of the total floor space of all units in a given project. The cap is checked at ownership registration and directly affects how a developer markets and sells to international buyers.

Resolving Construction Disputes

Construction disputes can be resolved through litigation in the civil courts or through arbitration. The Thai Arbitration Institute (TAI), which operates under the Office of the Judiciary, handles contract disputes including those from construction agreements.¹¹ Because TAI is government-funded, it charges no institutional fees; parties pay only the actual expenses of proceedings such as document delivery and recording. For construction disputes involving substantial sums, the savings against private arbitration institutions are considerable.

To use TAI, both parties must have agreed to an arbitration clause in their contract or reach a separate agreement to arbitrate after the dispute arises. Building an arbitration clause into the construction contract from the outset avoids the common situation where parties cannot agree on a dispute resolution mechanism once the relationship has already broken down.

1
Building Control Act of Thailand. Building Control Act 1979
2
Japan International Cooperation Agency (JICA). Existing Ministerial Regulations Based on the Building Control Act
3
Office of the Council of State of Thailand. Town Planning Act, B.E. 2562 (2019)
4
Noen Khilek Subdistrict Administration Organization. Building Construction, Modification or Demolition Permit Request Application Form
5
Office of the Council of State of Thailand. Enhancement and Conservation of the National Environmental Quality Act
6
SAMUIFORSALE. Thailand Civil and Commercial Code (Part II)
7
Baker McKenzie. Thailand Upcoming Changes to Increase Maximum Wage Base for Calculation of Social Security Fund Contributions Starting From January 2026
8
UNCTAD. Thailand – Foreign Business Act, Investment Laws Navigator
9
Baker McKenzie. Foreign Business Act B.E. 2542 – Schedule Three
10
Board of Investment Thailand. Obtaining Foreign Business License/Certificate
11
Thai Arbitration Institute. TAI Overview