Brabrand Boligforening, a housing association in Brabrand, Denmark, encountered a problem in the residential area Gellerupparken. Due to leaky joints in the roof and balcony drains, rainwater had damaged the front of the buildings.

Gellerupparken consists of four- and eight-storeyed blocks of flats including a total of 5,000 balconies. The drains are embedded in the vertical facade components, and therefore, they are practically impossible to replace. The work was put out to tender, and Aarsleff obtained the contract for CIPP lining of the total 1,488 roof and balcony drains. 

The tube length applied in the four-storeyed blocks of flats was 12.5 m, and in the eight-storeyed blocks of flats the length was 22.5 m. The tubes were installed from the roofs down through the drainpipes at an insertion pressure of four bar. The tubes were able to pass displacements during installation and tolerate motion in the buildings. Once the resin-impregnated tubes were in place, they were heat-cured from below. Grids were mounted on protruding laterals, and connections were opened. Finally, Aarsleff executed a CCTV inspection.

The residents hardly felt any inconvenience at all from the work.