In August 2024, the residential project was completed and handed over. Ytong autoclaved aerated concrete blocks (AAC) and Silka calcium silicate units (CSU) were used in the construction, including large-format Ytong Jumbo and Silka Tempo elements, which significantly accelerated the construction process.

Modern architecture with respect to historic Karlín 

The residential building Iconik, developed by the KARLÍN GROUP, is the result of the work of the architectural studio EDIT!. The building is divided visually into two parts - a taller, narrow nine-storey building; and a lower, wider eight-storey building. The façade is decorated with handmade ceramic bands in two shades of cut brick, which refer to the industrial history of Karlín. The residential units are protected from the city traffic by French windows leading to loggias. 
 
Three underground floors include parking for 38 vehicles, 48 basement cubicles and technical facilities. On the ground floor there are two commercial units suitable for a restaurant or bistro; and an entrance hall to the 48 apartments, whose layouts range from 1-bedroom to 3-bedroom. The most striking feature of the building is the spacious two-storey duplex on the roof. 

Advantages of the combination of reinforced concrete with large-format blocks 

The house is based on drilled piles and Milanese walls that provided the construction pit. The lower floors are dominated by reinforced concrete structures, while from the 4th floor onwards, the load bearing and perimeter walls were lined with large-format Ytong Jumbo and Silka Tempo blocks. This change to the original plan, which envisaged reinforced concrete construction of the ceilings and walls, allowed for faster construction and reduced costs. 

"The use of large-format elements on a relatively small construction site in the center of Prague was unusual, but it paid off. With an area of approximately 800 m² of Ytong Jumbo Statik blocks, the construction company saved 143 hours, 3,570 working steps and 1.1 tonnes of mortar. For Silka Tempo blocks with an area of approximately 1,800 m², the savings were 564 hours, 20,510 working steps and 3.8 tonnes of mortar," says Jan Tinka, Key Projects Manager at Xella Czech Republic. 

Efficient construction even in challenging conditions 

The construction site of only 210 m² required efficient logistics. The space had to accommodate not only the site equipment, but also facilities for the concrete pump, mixer trucks, construction lift and plaster silos. This is why the large-format blocks combined with mini cranes provided by Xella proved to be the right solution. "For the construction of an apartment building in the city center and in a space with such a minimal site area, we were perhaps the first in Europe to use these elements," says Ing. Petr Čeněk from Metrostav, who handed over the project together with his team. 

Why choose a combination of monolith and masonry construction? 

There are several advantages to switching from reinforced concrete to masonry structures: 

- Lower costs- masonry structures are more cost-effective than monolithic structures.

- Speed of construction - the use of large-format blocks speeds up construction.

- More efficient use of cranes - mini cranes allow other professions to work in parallel.

- Better acoustic properties - Silka sand-lime blocks provide excellent sound insulation with reduced wall thickness. 

 
"At Iconik we wanted to test large-format blocks on purpose. They proved successful and we subsequently used the experience on another project in Prague-Hrdlořezy," adds Ing. Čeněk. 

The future of large-format blocks in residential construction 

After the success of the Iconik project, Metrostav decided to continue this method of construction on other projects. Experience has shown that the combination of reinforced concrete with large-format masonry elements is not only faster, but also more economically advantageous - costs are approximately 10% lower than for pure reinforced concrete construction. 
The use of large-format Ytong and Silka blocks is thus becoming an increasingly popular choice for developers and builders looking for efficient and sustainable solutions for modern residential construction.