The new building in Zagreb's business district has a total area of over 15,000 m², which includes office spaces of 9,000 m² and hospitality areas of 6,300 m².
Its ventilated curtain wall facade helps reduce energy consumption and decrease CO₂ emissions.
The responsible architectural firm was Svebor Andrijević Zagreb under the leadership of Senka Dombi. The facade cladding of approximately 5,000 m² was commissioned to the company Keratek from Zagreb. The 6-mm-thick ceramic panels were mainly cut to 240 x 120 cm and 240 x 90 cm. These were adhered by the facade builders to the ATK 100 Minor substructure from BWM Fassadensysteme. A glass mesh on the back of the panels prevents them from breaking off and falling, should they be damaged. As cladding material, thin, large-format ceramic panels with a flexural strength over 70 N/mm² were used, which, together with the BWM substructure, weigh about 15 kg/m². Facade ceramics are weather-resistant and resistant to aggressive environmental influences. The cladding material is frost-proof and does not fade even under intense UV light. Rain cleans the smooth surface, making it self-cleaning. The ceramic cladding scores with a long service life, low maintenance, and cost-effectiveness. Depending on the mineral wool thickness, the ventilated curtain wall facade absorbs noise up to 15 dB. It also keeps the walls dry and ensures a healthy indoor climate. By executing the ventilated curtain wall facade with open joints, wind load is reduced by up to 50% according to calculations.
Structural Calculation and Assembly Plan
The structural calculation and assembly plan were prepared by BWM Fassadentechnik GmbH from Leinfelden-Echterdingen. Based on this, the quantity determination was then created.
After determining the loads including all relevant parameters, the choice fell on the distance-bridging, proven and safe BWM substructure ATK 100 Minor, onto which the panels were glued.
The structural calculation was carried out, among other things, based on the weight of the facade cladding material, the panel size and wind load as well as the distance and load-bearing capacity of the supporting walls and was applied with corresponding partial safety factors. For thin claddings, such as the selected ceramic panels with a thickness of 6 mm, it was necessary for the vertical profiles to have a maximum spacing of 500 mm.
Assembly and Preparation
Before ordering materials, a geodetic survey was conducted with information on the vertical and horizontal deviations of the walls. This facilitates the selection of wall angles in case of on-site tolerances.
Before installing the profiles, a non-combustible thermal insulation made of mineral wool boards with a thickness of 16 cm was installed, covered by a vapor-permeable fleece that allows diffusion.
Material for thermal separation was installed under the L-brackets. The load-bearing capacity of the adhesive system used was tested in a laboratory with a ceramic tile sample and approved after official certification. To safely use this on the construction site, the air temperature had to be between 8 °C and 35 °C. The humidity was not allowed to exceed 65%. Observing these conditions, the facade installers applied the adhesive, ensuring that the aluminum profiles and panels were colder than the air, thus preventing condensation on the cold surfaces. After only six months of construction, the project was completed to the satisfaction of all project participants.
