Day care centre in Karlsfeld: weather protection roof with 45 m span without anchoring possibility
One thing was clear when the renovation of the "Treasure Island" day-care centre in Karlsfeld near Munich, which cost over eight hundred thousand euros, was due to start: the facility would need to stay open! And that was the big challenge for all the trades involved in the renovation. Because children are not only curious, but also unpredictable. And that's why it was immediately clear to everyone that it was not enough just to put up the classic sign "No playing - parents are liable for their children". The construction site had to be absolutely childproof, and that's not exactly a piece of cake with a building like this.
Many a child must have been distracted from playing and had their noses firmly pressed against the window in curiosity when heavy transporters and crane trucks drove up outside to set up the construction site. In this case, however, setting up the construction site meant erecting a work and protective scaffolding and providing the entire kindergarten building with a weather protection roof so that the work could be carried out quickly and unhindered by the weather. The entire roof area was in urgent need of renovation because it had become leaky in many places, which would have resulted in major consequential damage if no action had been taken immediately.
The contract for scaffolding and weather protection roof was awarded to the company Krämer Gerüstbau GmbH from Bockhorn, headed by Florian Krämer. And this company, which has made a name for itself nationwide with special scaffolding constructions and especially weather protection roofs and enclosures in the seven years since it was founded in 2013, faced a major challenge this time in two respects:
On the one hand, a roof with a span of approx. 45 metres had to be erected without the possibility of mounting a downstand beam or being able to support the roof in between. On the other hand, there was no possibility whatsoever on the actual building to anchor the scaffolding structure that was to support the roof. But it is precisely these challenges that have made Gerüstbau Krämer a real specialist scaffolding company in recent years.
For the roof construction, Gerüstbau Krämer chose the MULTI-ROOF system from Scafom-rux. With the special K-frames, spans of 40 metres and more can be achieved. K-frames are elements with an overall height of 1.80 m and a length of 2, 3 or 6 metres. Vertical tubes and diagonals are reminiscent of the letter K, which is how the product got its name. These girder elements, which can be connected to each other with a positive and non-positive fit, have an enormous stability, which makes precisely these large spans possible without a tension band. Actually, these K-frames from the MULTI-ROOF system are nothing more than system-free, oversized lattice girders. However, they have some special advantages. Although they can be combined with any scaffolding system, they are part of the Scafom-rux RINGSCAFF system due to the integrated modular scaffolding connections. This means that ledgers and diagonals from the existing modular scaffolding stock can be used to connect the individual frames to each other or to erect walkway cantilevers without any major additional investment.
A day-care centre that continues to run normally, extremely cramped conditions for the pre-assembly of the roof trusses and a building that does not allow any anchoring are not exactly the best prerequisites for a smooth process. But Florian Krämer left nothing to chance in the planning. The over 40-metre-long segments of the roof construction were brought into position with a 160-tonne truck-mounted crane and placed on the support rails with millimetre precision. To compensate for the lack of anchoring possibilities, the supporting scaffolding structure was ballasted with concrete blocks with a total weight of 181 tonnes. For the roofing, elements from the cassette system Alu-Rasant by Scafom-rux were chosen. These elements, made of a lightweight aluminium-steel combination, have considerable weight advantages and have a positive effect on the overall weight of the construction.
An escape staircase attached to the outside of the building had to be elaborately bridged with a steel construction made of HEB 300 girders, which meant another static challenge when calculating the load-bearing scaffold construction.
The entire scaffolding structure was erected over a period of 2.5 weeks. 4 skilled workers from Gerüstbau Krämer were on duty during this time. The estimated service life for the weather protection roof was 10 weeks. And when the roof, scaffolding and the construction crane disappear after this time, many of the children of the "Treasure Island" will certainly have a clear career wish: scaffolding erector.