Structures
Building on land you don't own: Thailand's accession rule for informal builds and boundary encroachments
Civil and Commercial Code Sections 1310–1312 answer a question that comes up constantly on Koh Phangan's subdivided hillside plots and informal family arrangements: who owns a building put up on someone else's land? The default rule is counter-intuitive — the landowner, not the builder, ends up owning it — and a separate provision handles the common case of a structure that simply spills a little over the boundary line.
Right Way Phangan · Editorial
Updated 14 September 2026
If you fund or build a structure on land titled to someone else — a Thai partner, a friend, or a plot you're mid-negotiation to buy — who legally owns the finished building? Absent a registered superficies, usufruct or lease (see superficies vs usufruct vs lease), the answer isn't "whoever paid for it." The Civil and Commercial Code's accession rules (Sections 1310–1312) decide it instead, and the default outcome surprises most people: the landowner ends up owning the building, not the person who built it.
The default rule: Section 1310 — the landowner ends up owning the building
Section 1310 states that if a person, in good faith, constructs a building on another person's land, the landowner becomes the owner of the building — but must pay the builder for the increase in the land's value caused by the building. There's a carve-out: if the landowner can show the builder was negligent about not realising the land wasn't theirs, the landowner can instead refuse the building outright and demand it be removed and the land restored — unless that would be unreasonably costly, in which case the builder must buy the land (or the relevant part of it) at market price.
Bad faith changes everything: Section 1311
If the builder knew the land wasn't theirs and built anyway, Section 1311 flips the default: the builder must restore the land to its original condition at their own expense — in practice, demolish and clear it. The landowner has an alternative, though, entirely at the landowner's own option: keep the building as-is and pay the builder either the building's price or the amount by which it increased the land's value, whichever the landowner chooses. The builder doesn't get to pick this outcome; only the landowner does.
The boundary-encroachment variant: Section 1312
A different, narrower scenario: you own your own land and build on it in good faith, but the structure ends up extending a little over the boundary onto a neighbour's plot — a common outcome on Phangan's informally surveyed hillside land, where a fence line and the cadastral map don't always agree (see Land Code Section 69 bis boundary re-survey). Here a good-faith encroacher keeps ownership of the whole building, but must pay the neighbouring landowner for the land actually used and have a servitude registered over the encroached strip. If the encroachment was in bad faith, the neighbour can force removal at the builder's expense instead.
Why this matters on Koh Phangan specifically
- Informal builds on a partner's or friend's land — a common Phangan pattern where a foreigner funds a villa on land held by a Thai partner without ever registering a superficies. If the relationship sours, Section 1310 — not the couple's private understanding — decides who owns the finished villa, and it isn't automatically the person who paid for it.
- Subdivided hillside plots with informally marked boundaries make Section 1312 encroachment disputes a real risk — pair this with the law of neighbouring properties and the way-of-necessity/servitude guide for the related access and boundary mechanisms.
- "Good faith" is a factual question a court decides, not a label either side can simply assert — it turns on whether the builder reasonably believed they owned the land or had a right to build on it at the time.
- None of this substitutes for registering first. A superficies or long-term lease registered before construction starts (see building a villa on Koh Phangan) avoids the accession question entirely — Sections 1310–1312 are the fallback default that applies only when nobody registered anything and the arrangement falls apart.
The practical lesson isn't that these rules are a trap to fear — it's that they're the state's answer to a question you should never let a court decide for you. If you're funding or building on land that isn't titled in your own name, registering a superficies or lease before laying a single brick turns an uncertain accession dispute into a documented, enforceable right.
Key points
- Section 1310's default: a good-faith builder who puts a building on someone else's land does not end up owning it — the landowner does, subject only to paying the builder for the resulting increase in the land's value.
- If the landowner can show the builder was negligent about not owning the land, the landowner can refuse the building and demand removal instead — unless removal is unreasonably costly, in which case the builder must buy the land outright at market price.
- Bad-faith construction (Section 1311) is worse for the builder: the default is restoring the land to its original state at their own cost, though the landowner can instead choose to keep the building and pay for it or for the increased land value.
- A good-faith boundary encroachment (Section 1312) — a building that legitimately spills slightly over a property line — works differently: the builder keeps the building but must pay for the land used and register a servitude over the encroached strip.
- These accession rules are the legal default only when nobody registered a superficies, usufruct or lease before building — the safe route is to register first, not to rely on a private understanding.
Sources
General information, not legal advice. Thai property law is fact-specific — verify any structure with a licensed Thai lawyer before you commit. Independent legal due diligence is part of every transaction we handle.
From reading to doing.
Every property we list passes checks like these — title, zoning, access and the real numbers — before it goes live. Browse what’s available, or find out what your own land or villa is worth.