Building Rules on Koh Samui

Ownership & the law

The rules that decide what you can build on Koh Samui, and where: building permits, height and coastal limits, slope and elevation restrictions, boundary set-backs, zoning and environmental assessments.

By Samui Real Estate, Property ConsultantLast reviewed November 20265 min read

Koh Samui’s natural beauty is protected by a set of building rules that are tighter than on the mainland. They are the reason the island has no high-rise towers and why many hillsides are still green. For buyers, they matter in two ways: they decide what you can build on a plot, and they decide whether an existing villa was built legally. This guide explains the main rules and how to check them. It complements our guides to buying land and due diligence.

Where the rules come from

Source	What it controls
Building Control Act and ministerial regulations	Permits, building standards, set-backs, fire safety
Environmental protection rules for Koh Samui	Height, coastal distance, slope and elevation limits; EIA requirements
The town plan	Land use zones, permitted building types and plot coverage
The local municipality	Issuing building permits and inspecting work

Building height

Height limits apply across the island and are why most condos and hotels are low-rise. Limits are typically lowest close to the shore and higher further inland, and they’re measured in metres from ground level. A plot’s permitted height affects how many storeys you can build and whether a view can be protected.

Building near the coastline

The coast is the most tightly controlled area. Near the shoreline, rules commonly:

• prohibit or strictly limit new buildings within a set distance of the high-water line;
• restrict building height and footprint in the next band inland; and
• control seawalls and changes to the beach.

For beachfront property, check exactly where the coastline boundary lies on the title, and what can be built in each part of the plot. See beachfront property.

Slopes and high ground

Much of Samui’s interior is steep, and many of its best views are on hillsides. To limit erosion and landslides, the rules:

• restrict or prohibit building on steep slopes above a set gradient;
• restrict building at higher elevations, with stricter controls or bans above certain heights; and
• may require engineering reports for foundations, retaining walls and drainage.

A plot’s slope is usually measured from a topographical survey. Two plots of the same size can allow very different houses if one is much steeper.

Set-backs from roads and boundaries

The Building Control Act sets minimum distances, for example:

• between buildings and public roads, depending on the road’s width;
• between windows, doors and balconies and the neighbouring boundary; and
• between buildings and waterways.

These rules shape the footprint of a house on smaller plots.

Zoning and plot coverage

The town plan divides the island into zones, colour-coded on the plan, that control land use (residential, commercial, conservation, agricultural) and how much of a plot can be built on. A hotel or commercial building may not be allowed in a residential or conservation zone.

Environmental Impact Assessments (EIA)

Larger projects need an Environmental Impact Assessment approved before building starts. The thresholds depend on the type and size of the project. For example, condominiums and hotels above a set number of units or rooms, or a set floor area, need one. In environmentally protected areas, lower thresholds can apply. Off-plan buyers should ask for proof the EIA has been approved. See buying off-plan.

The building permit process

1. Design with a licensed architect and engineer who know Samui’s rules.
2. Submit the application to the local municipality, with plans, engineering calculations and land documents (the title, or the lease and superficies).
3. The municipality reviews it, checking it against the rules, and may ask for changes.
4. The permit is issued. Building can start only after this.
5. Inspection and completion. Some buildings need a completion certificate before use.
6. House number and registration, so utilities can be connected permanently.

Buying an existing villa: was it built legally?

• There is a building permit for the house, and for any extensions or pool.
• The building matches the approved plans: size, height and position.
• The house has a house registration and number.
• Nothing has been built on land where building isn’t allowed.

A villa built without permits, or larger than its permit allows, can cause problems with resale, insurance, licensing and, in serious cases, enforcement.

Frequently asked questions

When you are ready to plan a home or a project, our architecture and design and development consultancy services can help.

General information only, not legal or architectural advice. Rules change; confirm the current position for your plot.