Building an unheated garage: structure, ventilation and price 2026

What does an unheated garage cost in 2026?

An unheated single garage (25–30 m²) typically costs €12,000–25,000 in 2026, built by a contractor. The cheapest steel-framed versions come in at €15,000–20,000. The price is driven mainly by size, frame material, doors and ground conditions. An unheated garage is roughly 30–50 per cent cheaper to build than a heated one, and there are no running costs at all – no heating bill ever arrives.

An unheated garage is enough when what you need is lockable weather protection rather than a working space. Most of the wear that erodes a car's value comes from direct weather exposure: against snow, ice and UV radiation an unheated garage protects just as well as a heated one.

Wall structure: no vapour barrier

The most important structural rule of an unheated garage: no vapour barrier is installed. The structure must be able to dry in both directions. Plastic sheeting in an unheated garage wall traps moisture inside the structure and creates a mould risk – this is the most common and most expensive building mistake in unheated garages.

A working wall from outside in:

• External cladding (timber or steel)
• Ventilation gap, about 22 mm
• Windproof sheathing board
• Load-bearing frame

Internal lining is not strictly needed. If you want plywood or boarding on the inside, fix it directly to the frame – no plastic in between.

A frost-insulated ground-bearing concrete slab makes a suitable foundation. Outbuilding foundations typically cost €2,000–7,000, and the spread is explained by the ground – on soft ground, confirm the foundation method before requesting quotes.

Condensation is the unheated garage's main problem

When warm, moist outdoor air meets cold surfaces, water condenses – especially on the underside of steel roof sheeting and on the car's metal panels. The same happens when a snow-covered car is driven in and the snow melts. The answer is effective passive stack ventilation:

• At least two inlet vents low down, about 20–30 cm above the floor.
• At least two extract vents high on the opposite wall, close to the eaves line.
• Anti-condensation coating or an underlay beneath the steel roofing.

This keeps the air changing constantly, removing moisture before it can settle on surfaces. Also make sure air can circulate under the eaves and beneath the roofing. Don't skimp on vent sizes – passive ventilation's power comes from the height difference and the open area of the vents.

How does a car keep in an unheated garage?

Well. A lockable garage shields the car from damp, snow, ice and vandalism. In a well-ventilated unheated garage a car can actually keep better than in a poorly ventilated heated one, where constant thawing and re-wetting accelerate corrosion. If you charge an electric car in the garage, fit a purpose-designed charging point (€1,300–3,500 installed) – charging from an ordinary socket is only a stopgap limited to 8 amps, and a working smoke alarm is a basic precondition for charging.

Unheated garage, heated garage or carport?

• Carport: turnkey €7,000–30,000. The open structure ventilates itself and never suffers condensation, but offers no protection against vandalism or frost.
• Unheated garage (25–30 m²): €12,000–25,000. Lockable weather protection with no running costs; needs working ventilation.
• Heated garage (25–30 m²): €18,000–35,000. Dries the car and doubles as a workspace, but heating costs €200–1,200/yr and the structural requirements are stricter (vapour barrier, ventilation).

If the budget is tight and the plot has room, a carport combined with a separate store often does the same job as a garage.

Does an unheated garage need a permit?

Under Finland's Building Act, in force since the start of 2025, an enclosed building of at least 30 m² or 120 m³ always requires a building permit (rakentamislupa) – the old rakennuslupa now goes by this name. A garage under 30 m² may be permit-exempt, but municipal interpretations vary, so check with your own building control office. The permit is applied for from the municipality with main drawings, and processing times and fees vary by municipality. A carport is in a different position: one under 50 m² needs, as a rule, no permit. Even a permit-exempt building must be reported to the building register, it affects property tax, and the local plan, boundary distances and fire regulations apply in any case.

Checklist

• Budget €12,000–25,000 for an unheated single garage in 2026.
• No vapour barrier – the structure must dry in both directions.
• Wall from outside in: cladding, 22 mm ventilation gap, windproof sheathing, frame.
• Ventilation: two vents low down, two high up on the opposite wall.
• Choose anti-condensation coated steel roofing or fit an underlay.
• Check the permit position with the municipality – interpretations of the 30 m² limit vary.

• An unheated 25–30 m² garage typically costs €12,000–25,000 in 2026.
• The structure is built without a vapour barrier: cladding, 22 mm ventilation gap, windproof sheathing and frame.
• Condensation is controlled with ventilation: two inlet vents low down, two extract vents high up.
• Anti-condensation coating or an underlay under the steel roofing stops water dripping onto the car.
• An unheated garage is 30–50% cheaper to build than a heated one, with no heating costs.
• A garage of 30 m² or more needs a building permit; a carport under 50 m² is usually exempt.