Since the beginning of the 21st century floating buildings have been growing in popularity in Poland. According to market research and quantitative studies, the majority of operative Polish floating buildings serve for commercial purposes, such as short-term rentals, vacation houses and floating marinas. Simultaneously, despite the increasing demand, the development of floating buildings in Poland is limited by the inconsistent legislation, government policy and, most importantly, natural conditions of Polish inland waters. The most attractive sites for floating architecture are the semi-natural lakeshores and riverbanks. At the same time, low water levels and poor maintenance of many Polish basins require special architectural and engineering solutions. The article presents our experience with meeting the market’s demand for small cost-effective floating commercial buildings despite the local shortcomings of inland waters on the example of the floating apartment built in 2019 on the Roś Lake in Pisz, Poland. The presented building was intended as a water-based extension of the existing hotel on land. It was designed as a “modern barn” with all-glazed gable wall allowing for a spectacular view to the lake. With a 50 sqm footprint, the one-story house with a mezzanine has a small draft of 33 cm and meets the stability criteria defined for inland waters. The presented case study shows that integrating the naval architecture theory, Building Information Modeling simulation along with cutting-edge construction techniques such as Scottsdale Construction System (SCS) and polyurethane spray insulation, can bring significant progress into the development of the floating buildings market in Poland.