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The Building Act has been reformed, and the change particularly affects small-scale construction. In 2025, at the beginning of the year, a law came into force under which you may build on your own plot without a building permit a garden building of up to 30 square metres , such as a garden sauna or cabin. If building a garden sauna is on your agenda, this article gives you useful information for your project.
The new Building Act in a nutshell
The new Building Act came into force 1.1.2025. The reform has made the process of building a garden sauna easier in the following ways:
- Since January, under 30 m2 garden buildings, which are not intended for residential use, can be built without a construction permit.
- A notification procedure or consultation of neighbours are no longer needed either.
- The Building Act, fire safety regulations and municipal regulations must still be followed, and responsibility lies with the developer.
See below what people are asking about the building permit change. You will also find answers to the most frequently asked questions, such as:
- How many buildings under 30 square metres can be built on a plot without a permit?
- How close to the shore can a sauna be built?
Even though no permit is needed, the Building Act must be followed
Building a garden sauna or sauna cabin correctly is still the developer's responsibility. Note in particular that the building rights, minimum distances and fire safety regulations must be complied with.
Any local detailed plan, shoreline plan, municipal building ordinance or building guidelines must also be followed. If you want to deviate from these, you must apply for a derogation permit.
With a reliable, domestic sauna supplier, the process is worry-free. At Ehta, we always ensure that buildings comply with fire safety regulations and building laws. We will also help you clarify municipal regulations if you wish.
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How the Building Act reform has affected construction in practice
The reform of the Building Act seems to have been a success. Lighter bureaucracy has increased small-scale construction, even though the number of building permit applications has fallen by around 30-40%, depending on the municipality.
Sauna cabins in particular – buildings with a larger living area in addition to the sauna – are now being built in large numbers.
According to a story published by Yle in October 2025, the ’garden sauna law’ that municipalities feared has not brought major problems such as a flood of appeals either. So the construction of small buildings such as garden saunas has gone smoothly.
A few buildings have had to be demolished or moved to a different spot, but all in all the reform has also pleasantly surprised municipal building control.
Talk on the change in the law at the Spring Fair in Helsinki, 24.3.2024
At the time of the 2024 Spring Fair, the new Building Act was still to come, but it sparked a lot of discussion. A talk was held on the fair's spring stage, in which Ehta Group's CEO and sauna master Ville Laitila explained what the change in the law means in practice. People also asked questions on the subject, which the sauna master answered.
You can watch Ville's talk in the video below. Below the video we have gathered questions people frequently ask and the answers to them.
Questions and answers
Do the requirements for a building permit vary between municipalities?
Since the new Building Act came into force at the beginning of 2025, buildings under 30 square metres can be built everywhere without a building permit. Municipalities can set various construction-related rules in their building ordinance, which it is worth being aware of. Municipalities cannot however, impose stricter requirements than the law for obtaining a building permit.
Is a permit needed if the building has a fireplace?
Unlike before, a fireplace does not affect whether a permit is needed. From now on, garden saunas and other buildings under 30m2 with a fireplace can be built without a construction permit.
How is it determined when a building is intended for residential use?
A building is intended for residential use if it has cooking facilities, in practice a cooker.
What information will be required in future for an application for a deviation permit?
According to current information, an application for a derogation permit will require the same attachments as now. These are an area map, a site plan, a document showing control of the building site and a report on consultation with the neighbours.
How many buildings under 30 square metres can be built on a plot without a permit?
As many as you like. The Building Act does not take a position on this. However, the local plan or the municipal building ordinance probably restricts the number of buildings.
Will there be any new red tape now that the building permit requirement is being removed?
Not as far as we know. For example, the new Building Act does not recognise a notification procedure, so no notification is needed either. The only requirement in future is to report new buildings to the Tax Administration for property tax purposes.
Can a cabin built without a permit be suitable for year-round use?
Yes, you can. The wall thickness or heating method of the building does not affect whether a building permit is needed. The only thing that matters is whether the building has a cooker. Under the Building Act, a building without a building permit may not be used for residential purposes, and a cooker is considered equipment intended for residential use.
How close to the shore can you build a garden sauna?
Minimum distances and floor area conditions for shoreline construction vary from one municipality to another. The new Building Act has not changed this. The distance from the shore required for a smallish lakeside sauna is usually around 10-20 metres.
Is a permit needed if the building will have running water and drainage
No. A water supply, sewer or, for example, electrical installation does not affect whether a construction permit is needed.
Can a garden sauna be built without a permit if the plot has no building rights?
No, you cannot. The building rights on the plot must not be exceeded. Exceeding the building rights is only possible with a derogation permit.
This is how to build a garden sauna – guidelines for planning and carrying out a successful project:
1. Find out the starting points for building
Find out whether you need a building permit, how much building rights your plot has and whether there are other special regulations you need to take into account. Common considerations include the distance of the sauna from other buildings and from the neighbours' plots. Fire compartmentation can reduce the distance to the main building.
You can get information about your plot and the municipality's regulations by calling your local building control office.
If you want to make it easy, you can also contact Ehta's designer straight away. If needed, our service covers everything – right down to applying for the building permit and other paperwork.
2. Make a preliminary plan for your garden sauna
Make a preliminary plan for your garden sauna based on what you want from the building and what is possible.
Important questions:
- Just a sauna or a sauna cabin? Do you primarily want a good outdoor sauna, or something more at the same time?
- Sauna with changing room offers better facilities for storing towels or, if you like, for getting dressed.
- A WC or dry toilet + a small entrance hall with towel hooks and a bench may be the right solution for some.
- A small sauna cabin makes room for a pleasant space for cooling off and relaxing alongside the sauna, and even sleeping space for one or two. You can also add a fireplace and even a mini kitchen to a sauna cabin.
- A large sauna cabin already offers plenty of possibilities: a living area, a remote-working space, guest accommodation, a proper bathroom and WC, a kitchen? Perhaps you want to rent out your sauna cabin on Airbnb, in which case you could at best earn your money back in a few years.
- Wood-burning or electric sauna heater?
- With or without a deck? You can of course add a deck later, but it is worth taking the possibility into account when planning the location of the sauna.
3. Consider your own resources realistically
Think about what your own resources for building are: do you have the skills, or should you outsource part or all of the construction?
Nowadays there are lots of options and, for example, a prefabricated building can in the end be almost as affordable as a self-built one.
4. Finalise the plan and build (or have someone build) the foundations
Make (or have someone make) detailed drawings of the building. Once you know the exact dimensions, you can build the foundations.
Summer is a nice time to build, but late winter, for example, is also excellent for log construction. If you are planning to build in winter, have the foundations ready in the autumn.
Prefabricated buildings can be delivered all year round, but then the foundation work also has to be taken into account. The most affordable and reliable way is to have the foundations completed while the ground is unfrozen.
5. Enjoy the building process or get ready for an unforgettable moment when your ready-made sauna arrives in your garden
A ready-made sauna arriving on your plot is a memorable experience worth recording. If the package is truly comprehensive and the sauna comes with everything ready, right down to the sauna stones, you can enjoy a sauna that very evening.
If you build it yourself, be prepared for delays in the schedule and unexpected twists along the way. So set aside enough time to enjoy the building process. At its best, a sauna building project becomes a wonderful lifelong memory.
Kit delivery It could be a good compromise, which will help keep the project more manageable and make planning easier. Assembling a log building is great fun! Ehta can provide you with all the materials for your home garden, numbered and with precise instructions if you wish – down to the last nut. You will also receive support with planning and a professional to call if you get stuck.
Building a garden sauna can also be an effortless project
Would you like a completely finished garden sauna, ready for löyly, delivered onto the foundations? Professionals will also take care of the design for you – of course, so that you are happy with the result. If needed, we also offer a building permit service!
Ehta delivers garden saunas ready for löyly with experience of over 1,600 log buildings.
Our customers praise us for our excellent and warm customer service and the good value for money of our buildings. Many customers also appreciate that we are a family business building from Finnish logs in Perho, Central Ostrobothnia.
Every customer's dream is our dream too.
Take the first step now and book a remote design session here! If you would rather call us, you can find our contact details here for the right people directly.
