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One of the most impressive and visible projects of the Capital of Culture “Ruhr.2010” is the former "Union-Brewery" called “Dortmunder-U”, which has been restored to its original splendor. On the distinctive roof of the building, which is now used as a cultural center, the efficient “Prodach”-insulating system was installed.

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ROCKWOOL Mineralwoll GmbH & Co. OHG
ROCKWOOL Strasse 37-41
DE-45966 Gladbeck

Telfon: +49 2043 408-0
Kontakt: Andreas Gebing

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*(ro-en) project_developer*

Stadt Dortmund Sondervermögen

*(ro-en) project_architect*

Gerber Architekten GmbH
Dortmund

A "U" for Dortmund

At least since the Capital of Culture Year 2010 the world knows that the Ruhr district does not suffer from a lack of impressive scenery and an industry culture worth seeing.  Under the label "RUHR.2010", 53 cities and towns presented the Ruhr district as a European culture metropolis. The renovated building of the former Union Brewery resplendent in its new design thereby formed one of the most impressive and most visible lighthouse projects - not only affectionately described by Dortmund inhabitants as the "Dortmunder U".

Why it earns this nickname, the building does not keep secret in a single second: One can already see the golden "U" shining in all four cardinal points from far away, which is on the roof of the brewery building, protected as a historic monument. The 59 meter high tower used by the Dortmund Union brewery as a fermenting and storage tower was built in 1926 and 1927. It forms the center of a multi-part building complex, which was built with solid steel-reinforced concrete and which stands on a total of 40 pillars. After the brewery was relocated in 1994, individual building parts were first torn down and office buildings were erected on the land, which had become available. In 2007, the city of Dortmund purchased the entire area including the maintained and loved U tower.

In January 2008, the city council decided on the conversion to a center of creativity. The "Dortmunder U" is supposed to house university institutes, media art establishments  , and the art collection of the "Museum am Ostwall".  A utilization, which justifiably turned the building into a distinctive landmark for the European culture capital.

Protection from wind and weather

Right from the start of 2008, the "U" was comprehensively refurbished and prepared for its new tasks under the management of the Dortmund architectural office Gerber Architekten GmbH. Besides the immense facade areas, the roof areas needed to be renovated effectively, especially from an energetic point of view. Steffen Schuster from the Schäferdach GmbH located in Menden accompanied the roof modernization from the end of November 2009 with a construction team of an average of 21 employees. Among other, they were responsible for the roof covering of a shed roof surface of  around 1,600 square meters, which immediately joins the so-called "Cathedral room" with the "U" enthroned upon it. "The roof constructions need to fulfill very strict requirements after the renovation, overall. On the one hand, of course in terms of fire and heat protection, but on the other hand, especially with regard to noise protection and  resistance to weathering", Stefan Schuster describes the task formulation.

Metal roof construction as structure providing element

The topic weathering already concerned the Schäferdach team during the work in the first place. Partially substantial amounts of snow, thick layers of ice and minus temperatures in the two digit area - in short: a winter of the century - delayed the work time over and over. In a first step, trapezoidal sheets (type 85-250) were laid as a substructure parallel to the eave. A self-adhesive vapor barrier membrane (Bauder Tec KSD) was placed on top of it. On top of that, a non-ventilated, heat-insulated metal roof was to be created High durability, maximum weather resistance, efficiency, freedom from maintenance, and non-combustibility spoke for this construction from the planner's point of view.

Free of thermal bridges

The choice of a suitable insulation system thus immediately arose for Sascha Schäfer from the Schäferdach GmbH. "The upper shell of the roof should be formed by an angular standing seam roofing made from aluminum. The upper shells of a metal roof need to thus be basically connected through distance constructions with the supporting sub-shell. Conventional distance constructions, such as Z profiles for example, however represent substantial thermal bridges and influence the insulating effect
of the entire roof set-up in a negative way."

From the roof professional's point of view, the use of the ROCKWOOL "Prodach-Dämmsystem"offered the solution for non-ventilated metal roofs. Through the interaction of insulation, mounting rails and system-fasteners, almost heat bridge-free, double-shell metal roofs can hereby be produced.

Firmly anchored against wind suction

The non-combustible stone wool insulation board "Prorock" was first laid onto the vapor barrier in a thickness of 160 mm. Being resistant to compression, the mentioned insulation board can extensively absorb subsequent intermittent stresses on the metal enclosures, which are then securely transferred to the substructure. For the subsequent installation of the fastening rails, the team around Steffen Schuster cut two parallel, ca. 30 mm deep groves at the distance of the panel width into the surface of the insulation. Then the galvanized and painted fastening rails were placed evenly into the grooves and were selectively fixated on the trapezoidal profile supporting shell with self-tapping system fasteners. After that, the individual aluminum bands were fixated onto the fastening rails with adhesives. "We were able to extract the position of the fastening rails and the quantity of the required system fasteners from the layout drawing from ROCKWOOL, which had been designed just for this component. The rails had to be laid out vertically and exactly at the distance of the panel width of approximately 425 mm and were fastened in the inside area with ten system fasteners per square meter. The exact distance had to strictly be adhered to, so that the adhesives could precisely be set in the middle of the rails nine times per square meter for the fastening of the aluminum coverings. The rails were fastened with 20 system fasteners per square meter in the ca. 6 m wide roof edge areas. This stronger reinforced area results from the large wind suction in the edge and corner areas - after all, we are at a 45 m height and we're barely 22 meters below the highest U point of the building."

Separating layer to support the sound insulation

To maintain and to reinforce the already ideal sound insulation provided by the 160 mm thick stone wool insulation, the craftsman team still laid a studded fiber mat (Dörken Delta-Trela, 8 mm) directly onto the stone wool boards. With it, beating sounds of rain and hail are insulated once more. So much sound insulation was desired because the rooms situated under this roof area were supposed to be used as a museum exhibition area. The terminal covering made from aluminum was directly mounted onto the "Prodach" fastening rails with adhesives (five pieces per running meter) within a few days.

Tapered insulation between the sheds guarantees for rain water drainage

To be able to dependably drain the rainwater running of the sheds into the roof edge areas, the Schäferdach GmbH additionally setup a gradient with a gradient insulation between the "saw teeth" - also from non-combustible stone  wool (ROCKWOOL "Georock"). Sascha Schäfer does not doubt the longevity of this construction whatsoever: "This roof construction will last. Even if the next few winters were to be just as severe as the last one - the heat and noise protection effect of this construction will defy any weather." Simply the way it should be done for the landmark of a rough Ruhr district metropolis.