Guide · Building Register · 2026
Legalising an extension: what you need and how it works
Extensions, heated verandas and enlarged porches are often missing from the Building Register. It usually comes to light only when the house is sold or mortgaged. This guide explains what an extension needs before and after construction, and what to do if it was built long ago.
Building Register procedure from €190, full legalisation from €490 (incl. VAT). There is no state fee for a notice of use.
In short
- Before building:
- extending a residential building (footprint over 60 m²) by up to 33% – building notice and building design; over 33% – building permit.
- After building:
- a notice of use for a single-family or two-apartment house, with no state fee.
- Already built:
- the route depends on whether the extension was completed before 22.07.1995, before 1.07.2015 or later.
What an extension needs
Under the Building Code, an extension is the enlargement of a building. What it needs depends on the type of building and how much volume the extension adds. For a residential building with a footprint over 60 m², Annex 1 of the Building Code provides:
| Extension | Before building | After building (private house) |
|---|---|---|
| up to 33% of the original volume | building notice + building design | notice of use |
| over 33% of the original volume | building permit | notice of use |
Smaller buildings, ancillary buildings and apartment buildings have different requirements. See the table by building type in the guide “Notice of use or permit of use”. In areas of special architectural value and areas covered by a detailed plan, the local authority may set additional conditions, for example on exterior finishes.
The extension is already built but not in the register
The route depends on when the extension itself was completed, not when the main building was built: an extension added to an old house after 1995 is legalised as a later building.
- Before 22.07.1995 – the data are submitted with a notification and the construction date is proven.
- 22.07.1995 – 1.07.2015 – a building audit can replace the design, followed by a notice of use.
- After 1.07.2015 – a design, a building notice or building permit, and a notice of use, all after the fact.
All three routes, with steps, costs and timelines, are described in the guide “Legalising an unauthorised building”. For an extension completed before 1995, see also the guide “Buildings built before 1995”.
What to send us
- the address or Building Register code;
- when the extension was built and how big it is;
- any existing designs, plans and earlier permits or notices;
- photos of the extension outside and inside;
- whether the extension is heated and whether it has electricity, water or heating.
We review the register and your documents free of charge and give you a single fixed price before work starts. We arrange the survey, audit and any other specialist work. If the local authority asks for clarifications or changes to our work, we make them free of charge.
Frequently asked questions
Does an extension need a building permit?
It depends on the building and the size of the extension. If a residential building has a footprint over 60 m², an extension of up to 33% of the original volume only needs a building notice with a building design; a larger extension needs a building permit (Building Code, Annex 1). Requirements for smaller buildings are less strict.
Does an extension to a private house need a permit of use after construction?
No. Since 1 August 2026, a notice of use is enough after extending a single-family or two-apartment house (Building Code, Annex 2). There is no state fee for a notice of use.
The extension was built long ago but is not in the register. What should I do?
The first question is when it was built. For an extension built before 22.07.1995, a legal basis is presumed if the land is entered in the land register, and the data are submitted to the Building Register with a notification. For a later extension you need to show that it is safe – for work done before 1.07.2015, a building audit can replace the design.
Do I need my neighbour's consent?
Not always. The local authority may involve the owner of the neighbouring property in the procedure, especially if the extension is close to the boundary. In an apartment building or co-owned property, the other owners must consent.
Prepared by Seadusta.ee. Updated 31.10.2026. The local authority decides on the outcome of the procedure.
Enquiry
Get a free assessment
Briefly describe the situation. Within one working day we will tell you whether you need a permit of use or a notice of use is enough, how long it takes and what it costs in total.
- The enquiry and initial assessment are free and carry no obligation.
- If you can manage on your own, we will tell you so and point you to the right guide.
- Your data is not shared with third parties.
Prefer e-mail? Write directly to info@seadusta.ee.