The new building in Zagreb’s business district has a total area of over 15,000 m², which includes office space of 9,000 m² and hospitality of 6,300 m².
Its curtained back-ventilated facade helps reduce energy consumption and CO₂ emissions.
The responsible architectural office was Svebor Andrijević Zagreb, headed by Senka Dombi. Keratek from Zagreb was commissioned to clad the facade of around 5,000 m². The 6 mm ceramic panels were mainly cut to 240 x 120 cm and 240 x 90 cm. The facade builders glued these onto the ATK 100 Minor substructure from BWM Fassadensysteme. A glass net on the back of the panels prevents them from breaking off and falling down if damaged. Thin, large-format ceramic panels with a bending strength of over 70 N/mm² were used as the cladding material, which together with the BWM substructure weigh approx. 15 kg/m². Facade ceramic is weather-resistant and resistant to aggressive environmental influences. The garment material is frost-proof and does not fade even under strong UV light. Rain washes the smooth surface, which is self-cleaning. The ceramic cladding impresses with its long service life, low maintenance requirements and cost-effectiveness. Depending on the mineral wool thickness, the curtain-mounted back-ventilated facade absorbs noise up to 15 dB. It also keeps the walls dry and ensures a healthy indoor climate. By designing the curtained back-ventilated facade with open joints, the wind load is calculated to be reduced by up to 50%.
Static calculation and assembly plan
BWM Fassadentechnik GmbH from Leinfelden-Echterdingen has prepared the static calculation and the installation plan. The quantity calculation was then created on the basis of this.
After determining the loads taking into account all relevant parameters, the choice was made for the distance-overcoming, practically proven and safe BWM substructure ATK 100 Minor, to which the panels were glued.
The static calculation was based on the weight of the cladding material of the facade, the panel size and wind load as well as the distance and load-bearing capacity of the supporting walls and was subjected to corresponding partial safety coefficients. 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 preparations
Before ordering the material, a geodetic survey was carried out showing the vertical and horizontal deviations of the walls. This facilitates the selection of wall brackets with on-site tolerances.
Prior to the installation of the profiles, a non-combustible thermal insulation made of mineral wool panels in a thickness of 16 cm was installed with a vapour permeable fleece that allows diffusion.
Material for thermal separation was mounted under the L-brackets. The load-bearing capacity of the adhesive system used was tested in the laboratory with a ceramic panel sample and approved according to the official test certificate. To use it safely on the construction site, the air temperature had to be between 8°C and 35°C. Humidity should not exceed 65%. The facade builders processed the adhesive in compliance with these conditions. They made sure that the aluminium profiles and panels were colder than the air, thus preventing condensation from forming on the cold surfaces. After just six months of construction, the property was completed to the satisfaction of all those involved in the project.
