Logo Advokátní kancelář roku 2023

Duplex apartment

Is your current apartment cramped and do you long for a bigger and airier space? That’s exactly what a duplex apartment offers. However, duplexes are rare and it’s not easy to come across them for sale. Fortunately, however, you can build a maisonette, either by joining two adjoining flats or by combining a flat with a loft conversion. How does the law regulate this change? Find out in our article.

8 minutes of reading

Chapters of the article

What is a duplex apartment

A maisonette is a type of apartment that occupies two or more floors in a building. In a duplex apartment, the lower floor usually contains common living areas such as the living room and kitchen while the upper floor tends to contain bedrooms, study etc., thus separating the common living areas from the private ones. In our conditions, duplex flats are usually created by joining two flats above each other, by attaching a loft space to the upper flat or by adding an extension on the flat roof of the apartment building.

Advantages and disadvantages of a duplex apartment

Duplex flats can be tempting because of their unusualness and large space. However, you should consider certain factors before opting for this type of flat. Therefore, we bring you the main advantages and disadvantages of a duplex apartment.


  • Use of space: duplex apartments make efficient use of limited space on the ground (especially in densely populated cities). This allows the occupants to get more space in the same area.
  • Separation of living space: dividing common and private areas into two floors provides more privacy.
  • Airiness: duplexes tend to be more airy and sunny than traditional single-storey apartments.


  • Accessibility: Maisonettes are not suitable for people with physical limitations or those for whom stair separation could complicate their daily functioning. Therefore, these types of apartments are usually not suitable for the elderly or families with young children.
  • Temperature imbalance: duplexes can have the problem of heat imbalance. For example, in a situation where the upper floor is the attic of the apartment building and therefore there is heat build-up from the roof while cold air remains below.
  • Cost: In general, duplexes tend to be more expensive to acquire, build and maintain compared to single storey dwellings.
  • Resale issues: There can be problems with selling a duplex apartment. This is because it is a specific type of apartment that is not for everyone and therefore you may have fewer buyers when selling it than a conventional apartment.

Selling a duplex apartment

Maisonettes are sold in the same way as traditional single-storey flats. So, if you’re after a maisonette, you’ll need to keep looking. Some online portals offering flats for rent or sale, such as Sreality.cz, can make this search easier thanks to their filtering system. It is on the aforementioned Sreality that you can filter atypical apartments. Thanks to this option, you can search not only for duplex apartments, but also for basement or attic apartments. In addition to buying a ready-made duplex apartment, there is also the possibility to build this type of apartment. There are two main ways – joining two flats together and joining a flat with a loft.

Are you planning to buy or build a duplex?

We will provide you with a complete contractual and legal service. We can do it within 48 hours, flawlessly and professionally.

Connecting two apartments together

One of the ways to get a duplex is to buy two flats above each other, which you connect with a staircase. However, this isn’t just any way to do it, and if you actually decide to do this, there’s a lot of paperwork to deal with:

Co-op or HOA?

If you are a member of a housing association, you will need its approval to renovate. If you have a freehold flat, you don’t need the approval of the HOA. However, the exception is if you would be interfering with the common parts of the house, i.e. the wiring, etc. In any case, it is a courtesy to tell your neighbours that you are going to renovate and ask them to tolerate the increased noise level. In addition, it is also a good idea to give them an estimate of the time you will spend on the renovation.

If you are part of a unit owners’ association, you cannot avoid changing the owner’s declaration. This is the document that divides the ownership of the condominium into individual lots (apartments). When you build a duplex, two such units are joined together to form one unit. Therefore, it is necessary to include this change in the owner’s declaration. This change also gives you a higher ownership share in the common parts of the building. However, you will also have to make larger contributions to the repair fund.

Tip: Are you a member of the committee of a condominium or the board of directors of a housing cooperative? Are you dealing with the owners or members of the cooperative to merge two apartments and do not know what to do? Or do you think that someone has chosen the wrong legal procedure against you? Arrange with us to represent you at a meeting of owners or members of a condominium association.

Execution of the building permit

Next comes the building permit. You will need this if you are going to interfere with the supporting structures, if the modifications will negatively affect the safety of the building or if you plan to use unusual materials that differ in weight from the original materials.

In these cases, you will need to submit documentation of the planned renovation to the building authority , drawn up by a specialist. If you have a condominium, the condominium as a whole applies for a building permit.

In other cases, a building notice will always be required when joining two flats together. This has a big advantage over planning permission in that it is quicker to process. However, the disadvantage is that you will need the consent of all the people concerned. Your neighbours will therefore have to agree to the renovation. If only one of the neighbours does not agree, the building permit becomes a building notice and the whole process is delayed.

Tip: You can read how to apply for a building permit or building notification in our earlier article.

Flats in conservation care

If the flats you are converting are listed or directly in a listed building, the whole process will be a little more complicated. This is because the conservation officers are also involved in the process, and they can tell you what materials you can and cannot use, how to proceed with the renovation , and so on. It’s also not impossible that they will ban you from building a duplex altogether. Therefore, it is better to find out about these possibilities well in advance.

Tip: Getting a building permit and dealing with conservation officers can often be complicated for the layperson. Leave it to us. We work quickly, online and reliably.

Change at the Land Registry

Individual apartments are listed separately as separate properties in the Land Registry. Therefore, if two such separate properties are joined together when a duplex apartment is built, this change can be recorded in the Land Registry. In this case, a new owner’s declaration must be entered in the land register. However, this procedure is very complicated in practice, almost impossible. Therefore, it is better to keep the flats in the cadastre as two separate properties and thus save yourself the lengthy processing. However, you will have to take into account that you will have to pay all fees related to your apartment twice for both units separately.

Tip: Are you about to file a petition for entry into the Land Registry? We will help you with the drafting of the application so that everything is in order the first time and you do not miss important deadlines or lose money.

Connection of the apartment with the attic

If you own a top floor apartment and would like to combine it with the attic, the procedure will be similar to combining two apartments. However, there will be a few differences. First of all, you need to remember that the loft usually belongs to the common areas of the house and is therefore owned by all the owners of the flats. You will therefore have to get their consent and probably have to pay them (the exact rules should be contained in the statutes).

You will also need to enter into a development agreement. This is because the conversion of the loft will create an additional dwelling unit in the apartment building. This agreement must be signed by all the owners of the flats and unfortunately you cannot do without it.

You will also not be able to avoid the need to obtain a building permit when converting the land. In this case, the statics of the house are affected. Therefore, you will also have to submit a certificate from a structural engineer. In addition, you will have to report the change of use of the building to the building authority, i.e. the change from land to living space. You will then have to have the loft space approved once the building is completed.

The whole process of building a duplex apartment can be challenging, but with careful preparation and following all legal and building procedures, it is fully feasible. In the end, your new duplex apartment can give you exactly what you’ve been looking for – plenty of space, airiness and uniqueness.

Are you solving a similar problem?

Dostupný advokát team of online lawyers will solve it for you.

Real Estate Purchase or Sale

We provide a complete package of legal services related to real estate sales and purchases, including reservation contracts and escrow services. We will also help you with all tax and land registry issues. Our work is fast and accurate, ensuring a worry-free transaction. You’re also welcome to pay after services are provided.

Preset Prices
All services pre-priced for no surprises.
We Do Everything Online
Save time, money and the hassle of travel.
We Work Fast
90 % of issues get solved by the following day.
Experienced Team
We have specialists for every field of law.

Has this content helped you? Give it a rating

No rating yet. Be first to rate and help others.

Author of the article

JUDr. Ondřej Preuss, Ph.D.

Ondřej is the attorney who came up with the idea of providing legal services online. He's been earning his living through legal services for more than 10 years. He especially likes to help clients who may have given up hope in solving their legal issues at work, for example with real estate transfers or copyright licenses.

  • Law, Ph.D, Pf UK in Prague
  • Law, L’université Nancy-II, Nancy
  • Law, Master’s degree (Mgr.), Pf UK in Prague
  • International Territorial Studies (Bc.), FSV UK in Prague

Reviews of the Dostupný advokát service

Recenze služby

Lukáš Řezníček, Prague 6 – Bubeneč

before 3 years

I am giving both the website and service provided my very highest rating. Dostupný advokát found a hidden risk in my contract for the transfer of an apartment, which would have cost me tons of money.

Recenze služby

Jitka Salačová, Praha 6 – Řepy

before 3 years

In 2016 our Homeowner Association faced an unexpected event which led to the need for legal help. We reviewed many professional legal services, and chose Dostupný advokát because they remain available for contact practically anytime, without charging extra for being outside work hours. In addition, Mr. Preuss is available to speak with by phone, email (zobrazit více) and Skype, and he never fails to be respectable and discrete. We can confidently confirm the excellent quality of his service, loyalty and availability online.

Recenze služby

Jan Sekanina, Prague

before 3 years

My grandparents wanted to give me an apartment, but I was extremely busy at the time and couldn’t afford to put any time into finding out what I needed to do. I also had no idea how to get the transfer of ownership handled at the Land Registry. Dostupný advokát arranged everything for me, and (zobrazit více) the apartment transfer was legally arranged with no issues. Thank you and thumbs up!

View All Testimonials

You could also be interested in

About us in public media
Logo Česká advokátní komora Logo Advokátní kancelář roku 2023
Follow the news
Facebook Dostupný advokát Twitter / X Dostupný advokát