This bunker was constructed in 1940 and was designed with a complex hipped roof to both disguise and protect against bombs. The concrete used in its construction could have built nearly 9,000 houses, it has an outer wall thickness was approx 2 meters.
After years of disuse, the hip roof began leaking and the bunker was being called for either demolition or renovation, both very expensive projects. The surrounding areas presents a dichotomy in the clash between undeveloped areas with vacant buildings and rubbish coupled with areas that have been undergoing renewal.
German architect firm Index Architekten provided the perfect alternative: A light timber construction has replaced the old, run-down roof structure and sits perched atop the old bunker. The project integrates itself into the context of its surroundings, making use of already existing structures and gives the place a new image. Thanks to various interventions this "place of arts" has received a new touch without losing its industrial charm.
The bunker has a floor area of almost 30 by 15 meters. The two meter thick, soundproof walls exaggerate the war wasteland. However provide ideal conditions as a rehearsal room for musicians. The new addition designed by Index Architekten in 2004, provides around 50 new studios and rooms for artists for the Institute of New Media.
After a construction period of only nine months the double-story box with a height of 6.40 meters was completed. The stress relief is done via the bunker's outside walls. The shifting of the new structure from out of the dip line from the bunker has created a projection of 4 meters towards the East and freed space for common usage of the same size in the West.
The timber volume is set back slightly at all sides. This way the architects wanted to make room for an access balcony on both floors. A metal grid facade has been attached around the whole new building in line with the bunker's outside walls. This creates the impression of a compact, light and mobile box. The view from outside onto the grid structure imitates a closed facade, the view from inside the grid construction, however, opens up an unblocked view across Frankfurt's cityscape. The added structure can be accessed via a stair tower at the bunker's Western facade.
For the setup the architects chose to use a trapezoidal metal sheet construction. Its advantage in terms of statics is that it can be connected with a massive substructure, in economical terms this meant less time and effort. Cost-efficient materials such as pre-fabricated wall, floor and ceiling elements decreased costs to a total of 645,000 Euro. Thus, this is a rather cost-efficient project at a floor area of about 600 square meters, however, with a great effect.
