Building Permits for a New House in Thailand — Drawings, Licensed Designers, the 45-Day Review and the Notification Route

For anyone building a house on their own land, the first step before driving piles is a permit under the Building Control Act. Many think it's a hassle and that small houses don't need one, but unpermitted construction risks stop orders, fines and, for serious violations, demolition orders. It also causes problems obtaining a house number, permanent power and water, loans, or selling later. This guide outlines the process.

Where to Apply

Permitting authority lies with the local official where the land is located: district offices in Bangkok, municipalities or sub-district administrative organisations in the provinces. Check first how the Building Control Act and comprehensive city plan apply there, since height, setback and permitted building types depend on both.

Documents

Document	Details
Permit application	The local authority's form
Title copy	A deed or document allowing construction; owner's consent if the land belongs to someone else
Drawings	Site plan, architectural, structural and services drawings as required
Structural calculations	For buildings where the law requires them
Professional certifications	Signatures of the licensed architect and engineer with licence copies appropriate to building size
Supervisor's consent letter	For buildings legally requiring a construction supervisor
Owner's ID	ID card and house registration

Rules the Design Must Meet

Setbacks from boundaries: walls or balconies with openings such as windows or doors must be set back from neighbouring land by legally prescribed distances depending on building height; solid walls without openings can sit closer, sometimes requiring the neighbour's written consent. Setbacks from roads: depend on the width of the road in front. Open space: residential buildings must leave at least the prescribed share of the largest floor area as open space. Height and use: must comply with the zoning plan. In housing estates, check estate regulations too, which can be stricter than the law.

Two Routes: Permit or Notification

Permit route: submit the application and drawings; officials review and issue a permit within the statutory timeframe — in principle 45 days, extendable on grounds the law allows — and construction begins once the permit is issued. Notification route: the Act lets owners notify the local official of intended construction, with drawings designed and certified by qualified professionals. Once complete notification is filed, construction can start sooner, but officials may still review afterwards and order corrections if the design is non-compliant, so designers bear full responsibility. It suits projects with experienced architects and engineers.

Common Reasons for Rejection

1. Insufficient setbacks — especially windows too close to boundaries.
2. Too little open space — designs filling the plot without the required ratio.
3. Mismatched title and owner names — or missing co-owner consent.
4. Missing professional signatures or licences — or licence grades not matching building size.
5. Zoning conflicts — height or use inconsistent with the zone.

FAQ

Does a small single-storey house need a permit?

In principle yes, if the area falls under the Building Control Act, regardless of size. Confirm with the local authority.

Can I use standard or free government house plans?

Yes, but adapt the site plan to your actual plot, check setbacks and open space, and have professionals sign as required.

I already built without a permit. Can it be fixed?

Sometimes a retrospective application or correction is possible if the building doesn't substantially breach the law; if it does — wrong setbacks, for instance — parts may need modifying or demolishing. Get expert advice quickly.

Conclusion

Building permits protect owners, neighbours and future property value. Use professionally prepared drawings, check setbacks, open space and zoning at design stage, and choose the route that suits your project. Read about choosing contractors and legal extensions on the MyProperty blog.