Short Answer
It depends on the document.
There is no single “building certificate” that proves every aspect of a property is legally usable. A municipal letter identifying existing structures for a Land Department transaction may prove that those structures were recorded for that purpose, but it does not automatically prove lawful construction, approved alterations or permission for the buyer’s intended use.
Before investing, identify what each document was issued to certify and whether another approval is still needed for the proposed activity.
Why This Matters
Property due diligence can go wrong when official-looking documents are treated as interchangeable.
A file may contain a construction permit, approved plans, a completion or use certificate, alteration approvals, inspection records and a municipal letter identifying structures.
Each document answers a different question.
A buyer may therefore clear due diligence because “the municipality issued a certificate” even though the document says nothing about the building’s current business use or later alterations.
Typical Scenario
A buyer is reviewing an operating property.
The seller provides a municipal certificate listing the buildings on the land. The document was originally obtained to support a Land Department transaction.
Management asks:
“Does this prove we can continue using the property for the existing business?”
Not by itself.
Practical Analysis
01Start with the purpose of the document.
Check the issuing authority, legal basis and stated purpose. A document may identify structures, approve construction, confirm completion, approve a controlled use, approve alteration or record a periodic inspection.
02Separate construction approval from use approval.
Thailand’s Building Control Act distinguishes between construction and use. Section 32 treats certain buildings, including hotels, as controlled-use buildings. For such properties, the completion and use process must be checked rather than assuming that a construction permit alone authorises operation.
03Compare current use with approved use.
A building can lawfully exist but not be approved for the activity the buyer plans to conduct. The due-diligence team should ask both:
“Was this built lawfully?”
and
“What use was approved?”
04Check later alterations.
Additional rooms, enclosed terraces, pools, kitchens, extensions, new structures or other physical changes may require their own approvals.
The current layout should be compared with approved plans and later permits.
05Keep periodic inspection separate.
A completion or use certificate is not the same thing as an ongoing safety or inspection certificate. Continuing inspection obligations should be checked independently.
06Reconstruct chronology for older properties.
Where buildings predate the current legal regime or have been altered repeatedly, the answer may require a timeline of original construction, later works and current use rather than reliance on one historical document.
Where the property is income-producing, the building-control review should also be connected to the operating licence. A hotel, factory, restaurant or other regulated business may need premises that satisfy separate statutory conditions. Even a valid operating licence should not be used as a substitute for the underlying building approvals, and the building file should not be assumed to prove the operating licence position.
What We Usually Look At
We review title and land records, construction permit, approved plans, completion/use certificate, alteration permits, current approved use, municipal records, current survey, periodic inspection evidence and operating licences linked to the building.
Common Traps
Typical mistakes are treating every municipal certificate as permission to use the building, assuming a structure appearing on land records was lawfully constructed, checking only the original building and not later alterations, and relying on current operation as proof that approvals are complete.
Practical Next Step
Build one evidence chain for each material structure:
current structure → construction approval → approved plan → completion/use approval → later alterations → current permitted use → ongoing inspection
Any missing link should be understood before acquisition, financing or redevelopment.
Legal Sources
- Building Control Act B.E. 2522 (1979), as amended, including sections 21, 32, 32 bis and 33.
- Ministerial regulations issued under the Building Control Act on controlled-use buildings, building use and periodic building inspection.
- Department of Public Works and Town & Country Planning (DPT), current public guidance on construction permits, controlled-use buildings, use certificates and building inspection.
- Applicable local-authority public procedures for construction, alteration, use and building certification.
General legal information only. Please seek advice on your specific facts. Laws and regulatory practice may change.