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Products and solutions, 2009-07-24, 06:54 AM

Dancing on the roof

It was a special kind of refurbishment project, which (almost) ended in January in time for the official reopening.For two years, craftsmen from over 30 different trades have been getting Wuppertal’s Opera House, the venue of the world-renowned and award-winning Wuppertal Dance Theater under the direction of the late Pina Bausch, back into shape. During this period, some 500 workers have been bringing the listed playhouse building dating back to 1905 visually and technically into line with today’s standards. Among them were roofing specialists from ThyssenKrupp Xervon’s Building Maintenance Department. Their job was to upgrade about 5,000 square meters of roof surfaces (thermal insulation, waterproofing and fire protection), replace over 70 rooflights, install 400 meters of window sills and also carry out extremely extensive roof plumbing work.

The newest equipment combined with ancient craft skills

Wuppertal’s Opera House today displays little of its original architectural blend of Neo-Baroque and “Jugendstil” (German “Art Nouveau”). Having sustained serious damage in the Second World War, what was left of the original building envelope was integrated during reconstruction, but any attempt to replicate the style of 1905 was deliberately avoided. When the playhouse became one of the first West German venues to reopen its doors to the public in 1956, the rambling complex of five building units containing a total of 480 rooms and 13 staircases expressed the aesthetic mood of the Fifties – which is why it is listed as a monument today.

The building’s critical structural condition discovered at the end of the Nineties and, first and foremost, its inadequate fire protection made the now completed thorough overhaul necessary. ThyssenKrupp Xervon’s Building Maintenance Department was awarded the contract to carry out the complete modernization of the roof, inclusive of the plumbing work. This was supplemented by facade rehabilitation work, e.g. small cornice flashings and the installation of 400 meters of window sills. This was an extremely diversified and also challenging task, as the Wuppertal Opera House with its many corners and recesses has practically every conceivable roof system – including flat roofs, felt shingle roofing, metal roofing and tiled roofs. Even large sheet copper roofs, which are rarely encountered today, were handled by the roofing specialists of the Building Maintenance Department. Technical knowledge and craftsmanship were required for the skilled refurbishment of the over twenty different roof surfaces.

However, refurbishment in this case did not mean restoring everything to its original state, but involved installing thermal insulation complying with the German Energy Conservation Ordinance (or better) and the creation of flashover areas. On the large proportion of flat roofs, this was accompanied by the replacement of all the domelights of the smoke extraction systems. Over 70 had to be removed, disposed of and replaced.

Unusual roofing

The refurbishment of the areas of flat roof was a real challenge for the specialists. This is because the client, the building management department of the City of Wuppertal, had requested high-grade EPDM roofing membrane to waterproof the roof, and only a small number of specialist operators know how to go about this. “In the industrial sector, our roofers have been working for almost twenty years almost exclusively with this high-grade roofing membrane. The manufacturer recommends us as a specialist installer that has all the credentials for the laying of this material,” says project manager Dietmar März, highlighting a decisive advantage that the Xervon building maintenance experts could claim for themselves in their bid for the contract.

Eight to ten experts on site at all times

The Xervon roofers insulated the classic flat roof, consisting of a primed concrete slab, vapor barrier, thermal insulation and two-ply waterproofing, with 40 to 160 mm thick rigid PU foam slabs (k-value 035), depending on the existing insulation. The roof was then covered with the above-mentioned, extremely heavy-duty EPDM roofing membrane. The acid- and weathering-resistant material can be processed one ply at a time and the membrane’s edges are mechanically fastened to the substrate with screws, washers and plugs. The membrane laid on top of this overlaps this area by ten centimeters, and the plies are then welded together with hot air (and not with a naked flame). The line of bitumen which emerges in the joint is a visible assurance of joint quality.

Concurrently with refurbishment of the flat roofs, men were constantly at work on the other roofs as well. Eight to ten specialists from Xervon have been on site over the last two years and have applied their expertise on the various different types of roofing. The extensive and demanding roof plumbing work associated with this was carried out by a team under the leadership of a skilled plumber from Switzerland. Whereas in Germany roof plumbing is treated as part of the general roofing specialist’s training, it is regarded as a craft in its own right in Switzerland with a full course of training. This specialized know-how was very much in demand at Wuppertal’s Opera House. Many pieces and long sections of gutter outlets, gutter ends, gutters, downspouts and connecting sheets etc. were precision-cut and fitted.

Working simultaneously on five roofs

Essential for the success of roof refurbishment was not only the skilled performance of the work, but also, and more importantly, daily coordination with the many other trades at work at the Opera House – scaffold erectors, concrete pourers, painters, electricians, heating and ventilation specialists, electronic technicians, stage technicians, security experts and so forth. “Most of the time we were working on four to five roof surfaces at the same time. Because of the large number of trades involved, it was rarely possible to work on a single roof without interruption. But as work was in progress on several roofs simultaneously, it was always possible, if required, to down tools and continue work elsewhere. This way, no time was wasted,” recalls project manager März, looking back at the daily challenges of the refurbishment project.

“Sometimes we had to bring forward tasks at short notice. We were always able to react with great flexibility and speed,” says März in praise of his team. For the client it was important to hire efficient service providers that deliver not only the necessary expertise, but also the manpower to expand the workforce at short notice if required. Because this was the only way to closely dovetail the many different tasks at Wuppertal Opera House. The fact that this was actually achieved is demonstrated by the success of refurbishment. Xervon’s men put the finishing touches on the roof at the beginning of May by creating flashover areas on all rising building sections.

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