Koh Samui · building restrictions · data as of 16 August 2026
The island is zoned by elevation above sea level. Above 80 metres, development is prohibited with narrow exceptions — and the rule catches a good deal of what is currently on the market.
The restricted zone
Derived from terrain, not from any listing
By district
Share of listed properties that fall under a restriction
The controlling instrument is the Ministry of Natural Resources and Environment announcement for Surat Thani Province, B.E. 2568, published in the Royal Gazette (vol. 142, special section 199 ง) on 21 May 2025 and in force from 22 May 2025 for five years. It replaced the 2557 (2014) edition that much of the English-language material on the island still cites.
The Thai text uses ร้อยละ — percent. Slopes of 35–50 % allow a single dwelling of up to 6 m; above 50 % construction and alteration are prohibited outright. Sources stating “35–50 degrees” are mistranslating: 50 degrees corresponds to a 119 % slope, a gradient that barely exists on the island.
Guides published by agencies commonly lead with a scale of setbacks measured from the beach. In the text we examined, that scale sits under the provisions for the small outlying islands. Whether a separate setback applies to Koh Samui itself — from this instrument or from the town plan — we have not established, and it is not reflected on this map.
A plot above 80 m may still be buildable under the pre-2557 ownership exception. That exception turns on when private ownership arose, which can only be confirmed from the title record at the Land Office. The correct reading of this map is “verify before you commit”, not “refused”.
The restricted zone shown on the map is computed from terrain: a 30-metre elevation model with forest canopy and buildings removed, clipped to the coastline. It describes the island and the regulation — no property, seller or agency is identified anywhere on this page.
The district figures come from a census of 4,676 properties advertised for sale on Koh Samui across ten sources, taken on 16 August 2026. Of those, 3,429 published a location precise and plausible enough to compute terrain; the rest either publish no coordinates, publish coordinates that contradict their own stated district, or place the property implausibly far from any road.
| District | Properties checked | Under a restriction | Share |
|---|
Generally no. Land between 80 and 140 metres and above 140 metres falls in a zone where construction, alteration and change of use are prohibited. The main exception is land held in lawful private ownership before the 2557 edition of the regulation took effect, which keeps the right to a single detached dwelling of up to 6 metres. That exception can only be confirmed from the title record at the Land Office.
Percent. The Thai text uses ร้อยละ. Slopes of 35–50 % allow a single dwelling of up to 6 metres, and above 50 % construction is prohibited. Sources stating 35–50 degrees are mistranslating — 50 degrees is a 119 % slope, which barely exists on the island.
The Ministry of Natural Resources and Environment announcement for Surat Thani Province, B.E. 2568, published in the Royal Gazette volume 142, special section 199 ง on 21 May 2025, in force from 22 May 2025 for five years. It replaced the 2557 (2014) edition.
Among properties currently for sale, Chaweng Noi and Bang Por have the highest share under a restriction, and Bang Rak and Plai Laem the lowest. The spread between districts is roughly an order of magnitude.