In brief

• UOKiK fined developer Groen Konstancin I 1 176 000 zł for advertising attic conversions in its Konstancin-Jeziorna estate.
• The marketing promised more than 60 sq m of extra space by adapting the attic.
• UOKiK says the design assumed a two-storey flat and the attic could not be converted.
• The developer can appeal the decision to court.

Attic advertised as extra living space

The Office of Competition and Consumer Protection (UOKiK) fined Groen Konstancin I 1 176 000 zł for advertising an option that the building design did not support (Poddasze (nie)użytkowe. Kara UOKiK za wprowadzanie w błąd – podatki.biz) (Miało być dodatkowe 60 mkw. mieszkania. Deweloper ukarany przez UOKiK – Bankier.pl) (Kara 1,176 mln zł dla Groen Konstancin I za reklamę adaptacji poddasza – kobieceinspiracje.pl) (Obiecywał użytkowe poddasze, a nie zbudował nawet schodów. Deweloper ukarany – RMF24).

The developer built single-family houses and terraced houses with one or two units on the Groen Konstancin estate in Konstancin-Jeziorna. Its catalogs and website, covering the first and second stages, said buyers could enlarge their living space by adapting the attic and gain more than 60 sq m. The promotion presented the space for hobbies, a game room or a home gym, and suggested a guest room or studio if needed. Visualizations showed the attic already fitted out as a residential area (Poddasze (nie)użytkowe. Kara za wprowadzanie w błąd – UOKiK).

Why the conversion was not possible

UOKiK found that the attic could not be converted.

The developer can appeal the decision to court.

Who is affected and what comes next

Buyers of homes in the first and second stages of the Groen Konstancin estate who were shown the attic-conversion offer in marketing materials are affected. The decision was announced on Monday, 2 November 2026. The developer must pay a fine of 1 176 000 zł. The company may challenge the fine in court.