5 Oct 2026 · 5 min read
Do you need a permit to extend? The basics
When no permit is needed, the 2 m boundary rule and the townhouse rear space — read before adding a kitchen.
Thailand's Building Control Act 1979 says alterations and extensions need a permit, with some exceptions. This is a general summary — confirm with your district office or municipality.
When a permit usually isn't needed
Adding or removing up to 5 m² of floor, or 5 m² of roof, without adding or removing columns or beams; and replacing structure with the same material, size, number and type.
Distance from the boundary
Walls with windows, doors or vents must be at least 2 m from the boundary for buildings up to 9 m, and 3 m for taller ones.
Townhouses
A 2 m rear open space must stay clear as a fire escape — often exactly where people want a kitchen — so design carefully and talk to the estate office first.
Quick check: does this extension need a permit?
Answer all three to see the result
A first guide based on the Building Control Act 1979 only — not legal advice. Confirm with your district office or municipality.
