Building without a permit – what can you build in Finland in 2026?

The main rule in section 42 of Finland's Building Act (rakentamislaki) is clear: without a construction permit you may build a non-residential building under 30 m² and under 120 m³, plus a free-standing canopy under 50 m² – a carport, for example. Extensions follow the same rule: a non-residential building may be extended permit-free while the extension stays under 30 m² (under 50 m² for a canopy). The old action permits and notification procedures were removed from the law at the start of 2025.

A residential building always requires a permit, regardless of size.

When is a building classed as residential?

The decisive line is the fixed cooker: a building with a fixed cooker or hob is residential and needs a permit. A sauna stove or fireplace is not a cooker, so a garden sauna with its stove can be permit-exempt, and a WC, washing facilities and free-standing kitchen appliances are allowed too. A guest cabin with fixed cooking facilities is in practice residential – and permanent or holiday living in a permit-exempt building is not allowed, though occasional overnight guests are.

What do the rules demand even when no permit is needed?

The exemption removes the permit application, not the rules. Still binding are:

• The provisions of the local detailed plan and master plan, plus the plot's building right – a permit-exempt building uses up building right
• The municipal building ordinance, e.g. distance to the neighbour's boundary, typically 4–5 m without written consent
• The essential technical requirements: fire safety, a CE-marked stove and its safety clearances
• The fire regulations' 8-metre rule of thumb – if the gap between buildings is under 8 metres, the spread of fire must be prevented structurally
• Keep drawings and reports on file, and report any building over 5 m² to the tax authority for property taxation

The municipality's checkpoints disappeared, but oversight did not: the municipality can afterwards order a non-compliant building to be demolished. Responsibility for finding out the rules shifted from the authority to the builder.

Does the exemption work on the waterfront?

Not in the same way. Finland's shoreline provisions in the Land Use Act require either a building site designated in a plan or a deviation permit – even a small shore sauna on a new building site can need one, despite being under 30 m². Building ordinances also set minimum distances from the shoreline. Confirm the situation with building control before starting work.

Differences between municipalities

The law sets the boundaries, but building ordinances add provisions on top. Kirkkonummi's 2025 ordinance, for example, allows without a permit a carport under 50 m², an outbuilding under 30 m² and a covered terrace under 20 m², and requires four metres from the boundary unless agreed in writing with the neighbour. Always read your own municipality's ordinance. The other direction is firm: an ordinance cannot demand a permit for a building the law has made permit-exempt. Canopies hide one common pitfall: an open terrace canopy is permit-free, but glazing a terrace fully closed requires a permit.

What does the exemption save?

The saving in permit fees on small buildings is around €200–600, and you skip the processing wait. A log-built garden sauna or store is a typical permit-free project: a ready-made kit goes up quickly. Design responsibility remains, though – drawings must be produced and kept, even if they are not submitted to the municipality.

Price levels in 2026: a log garden sauna or guest cabin costs around €8,000–18,000 as a self-erected kit and €15,000–30,000 delivered fully built. Foundations come on top: a pier foundation €2,000–4,000 and a concrete slab €4,000–8,000. Year-round use calls for at least 90 mm laminated log or added insulation – 58 mm log is enough for summer use. The exemption has made this size class popular: garden saunas, guest cabins and barbecue huts are built in clearly greater numbers than before. A popular build is a 29.5 m² guest cabin with a sleeping area, WC and kitchenette without a fixed cooker – sized exactly to the exemption.

Checklist before permit-free building

• Check the plan and the remaining building right with the municipality
• Read your municipality's building ordinance: distances, sizes and area-specific restrictions
• Measure the distances to the neighbour's boundary and to buildings – a gap under 8 metres brings fire requirements
• On the waterfront: confirm whether a deviation permit is needed
• Report any building over 5 m² to the tax authority and keep the drawings

With these five points in order, permit-free building is exactly as smooth as the legislator intended: no applications, no waiting – but no excuses either, if the rules went unread.

• Without a construction permit you may build a non-residential building under 30 m² and 120 m³, plus a canopy under 50 m².
• A fixed cooker makes a building residential – a sauna stove or fireplace does not; that is why a garden sauna can be permit-exempt.
• A permit-exempt building uses up building right and must comply with the plan and the building ordinance.
• The distance to the neighbour's boundary is typically 4–5 m without written consent; a gap under 8 m to buildings brings fire requirements.
• The exemption does not work the same way on the waterfront – a new building site can require a deviation permit.
• Buildings over 5 m² must be reported to the tax authority, and the municipality can order a non-compliant building demolished.