Architect Jens-Uwe Lau: Back to the Future

After working as a construction manager for several years, graduate engineer Jens-Uwe Lau opened his architectural office in Bonn 10 years ago. The team of ten is able to realise several projects every year, from the design stage to handing it over to private investors and developers. His customers appreciate not only his creative and user-oriented designs, but also his precise preliminary calculation, his fair treatment of the companies involved and his sense for sustainability. And the fact that he is virtually always able to meet the construction time limit, the costs and the high quality standards has to do with his many years of experience, the intense communication with all parties involved and the professional controlling on the part of the respective project managers.

A portrait of architect Jens-Uwe Lau and project manager Kristin Prelec, standing in front of a bookcase

[Translate to english:] Dieser Ruf eilte dem Duo auch im Falle des Hochhauses in Erftstadt voraus und führte schließlich zur Beauftragung zum Entwurf, Planung und der Bauleitung des Neubaus von zwei fast 60 Meter hohen Fassaden, die das Gebäude in Zukunft beschützen sollen.

The office’s reputation also preceded it in the case of the high-rise building in Erftstadt. For these reasons, it was eventually commissioned with the design, the planning and the construction management of the new construction of two façades that are nearly 60 metres high and will protect the building in the future.

The focus is on the Erftstadt high-rise building, which was renovated with the help of PREFA.

It all began two years ago. In the course of the renovation of the flat roof, it was accidentally discovered that the two 350-ton exposed aggregated concrete façades on the gable sides of the house could not be saved after nearly 45 years. A majority of the supports had loosened, there was imminent danger and the community of owners was forced to immediately have the façades secured with steel nets before they were disassembled step by step. With the help of a special crane, the industrial climbers had to demonstrate their skills as they removed the concrete plates piece by piece before handing them over to the crane hook.

A close-up of the PREFA façade system siding.X in the colour P.10 light grey. The high-rise in Erftstadt was photographed from bottom to top.

[Translate to english:] PREFA Fassadensystem am Hochhaus Erftstadt

[Translate to english:] Auf der Suche nach einer nachhaltigen und leichten Ersatzlösung, stieß der Architekt recht schnell auf die bewährten PREFA Fassadensysteme.

The picture shows the renovated front side with the PREFA Siding X aluminium façade.

[Translate to english:] Renovierte Stirnseite

[Translate to english:] Die renovierte Stirnseite des Gebäudes erstrahlt mithilfe der PREFA Siding X. in der Farbe P.10 Hellgrau.

PREFA façade sidings on the Erfstadt high-rise building with a beautiful contrast to the blue sky in the background of the picture.

[Translate to english:] PREFA Fassadensystem am Hochhaus Erfstadt

[Translate to english:] Auf der Suche nach einer nachhaltigen und leichten Ersatzlösung, stieß der Architekt recht schnell auf die bewährten PREFA Fassadensysteme. Die Entscheidung fiel auf PREFA Siding.X.

When looking for a sustainable and light alternative solution, it did not take the architect long before he came across the proven PREFA façade systems. And he found a congenial partner in the object consultant Carsten Friedt, who already delivers constructive possible solutions in the planning phase and also serves as a link to the Schröder Bedachungstechnik GmbH from Cologne that was commissioned with the construction.

Project Manager Kristina Prelec remembers: “It was a very complex task. It wasn’t possible to convince the community of owners to choose a solution made of aluminium with a simple sampling. In a case like this, it was a great advantage that PREFA has its own photo service and could provide possible façade and colour variants with photomontages to help the clients in their decision-making process.”

It was eventually decided to use PREFA siding.X with the construction widths of 400 mm, 300 mm and 200 mm in the colour P.10 light grey. The clear installation scheme designed by the architect and the unique, striking longitudinal and transverse edges of the sidings contribute to the modern and timeless appearance of the two 900 m² and 59 metre high gable sides and therefore of the entire building from the 70s. This is topped off by an investment security due to a 40-year colour and material guarantee.

Together with Heribert Paul of the laying company, the expert for statics DI Jörg Friedrich of the engineering office Tragwerk and Carsten Friedt, the architect was able to clarify the feasibility and many other details. “Other laws apply for building heights like these. The wind suction, wind pressure and torsions of the building structure, fire and lightning protection as well as connections to the various different window types were very challenging. Due to the close collaboration between all trades, intelligent custom solutions and the perfect construction management by Dr. André Glaubitt of the engineering office Dipl.-Ing. Franz-Josef Bilo and Prof. Dr.-Ing. Matthias Middel, the new construction of the façades could be completed on time without any significant problems.”

Both Jens-Uwe Lau and Carsten Friedt see great potential regarding sustainable high-rise renovations across borders and hope that this example will set a precedent.

Other laws apply for building heights like these.

Jens-Uwe Lau

Jens-Uwe Lau draws on the following examples to illustrate the significance of the merger of industry and craft when developing custom solutions:

We were able to tackle the subject of wind suction and wind pressure relatively quickly. For a storm-proof assembly in heights of up to 60 metres, the sidings were secured with PREFA storm-proof clips without limiting the “freedom of movement” due to thermal changes or torsions of the building. In order to also withstand the building’s movements unscathed, the substructure was divided accordingly and the sidings were fastened with fixed and gliding points according to the PREFA laying plan.

This picture shows the construction site of the façade, where the Prefa storm-proof clips can be seen.

[Translate to english:] PREFA Sturmsicherungsclips

[Translate to english:] Das Thema Windsog und Winddruck hat sich schnell erledigt. Für die sturmsichere Montage in Höhen von bis zu 60 Metern wurden die Sidings mit PREFA Sturmsicherungsclips befestigt ohne dadurch die „Bewegungsfreiheit“ durch thermische Veränderungen oder Verwindungen des Gebäudes einzuschränken.

The picture shows the PREFA storm-proof clips for the sidings.

[Translate to english:] PREFA Sturmsicherungsclips

[Translate to english:] Das Thema Windsog und Winddruck hat sich schnell erledigt. Für die sturmsichere Montage in Höhen von bis zu 60 Metern wurden die Sidings mit PREFA Sturmsicherungsclips befestigt ohne dadurch die „Bewegungsfreiheit“ durch thermische Veränderungen oder Verwindungen des Gebäudes einzuschränken.

As a fire protection measure, a fire bar made of stone wool was established on every second floor, which was fastened with insulating material plates.

[Translate to english:] Steinwolle zum Brandschutz

[Translate to english:] Als Brandschutzmaßnahme wurde bei jedem zweiten Geschoss ein Brandriegel aus Steinwolle, welcher mit Dämmstofftellern aus Kunststoff befestigt wurde, errichtet.

Arrangement of the insulation plates behind the aluminium façade from PREFA

[Translate to english:] Dämmstoffteller

[Translate to english:] Im Falle eines Brandes schmelzen die nicht brennbaren Halterungen, die Steinwolle fällt in Richtung der Sidings und verhindert dadurch ein Übergreifen von Flammen und Rauch auf darüberliegende Stockwerke.

As a fire safety measure, a fire barrier made of stone wool that was fastened with insulation material plates made of a synthetic material was erected on every second storey. In the event of a fire, the non-flammable supports melt, the stone wool falls down to the sidings and thus prevents the flames and smoke from reaching the upper storeys.

In this picture you can see the lightning protection of the roof area.

[Translate to english:] ALU-Konstruktion der Blitzableitung

[Translate to english:] Der Blitzeinschlag wird über die Alu-Unterkonstruktion direkt zur Erdeinführung abgeleitet – das Fassadenbild bleibt so von außenseitigen Ableitern unbeeinträchtigt.

A close-up to the lightning protection of the high-rise building in Erftstadt.

[Translate to english:] Blitzableiter Detailansicht

[Translate to english:] Durch Blitzschutz konforme Zusammenschlüsse der Tragprofile wurden die Fangleitungen knapp unterhalb der Attika an die obersten Profile angeschlossen.

The picture shows the lightning protection of the façade.

[Translate to english:] Blitzableiter im Detail

[Translate to english:] Die Tragprofile der Unterkonstruktion wurden in die Ableitungen der Blitzschutzanlage einbezogen.

The support profiles of the substructure were included in the lightning protection system. Due to connections of the support profiles that comply with lightning protection, the lightning conductors were connected to the uppermost profiles right underneath the roof parapet. The lightning strike is directly passed down to the earth entry via the aluminium substructure, which means that the façade image is not impaired by external arresters.

The picture shows the windows and sidings in detail.

[Translate to english:] Detailansicht der Siding & Fenster

[Translate to english:] Die Anbindung der Fassade an die Fenster musste so gestaltet werden, dass ein Tausch von Fenstern auch künftig ohne großen Aufwand von innen durchgeführt werden kann.

[Translate to english:] Detailansicht der Siding & Fenster

[Translate to english:] Meist werden im Zuge von Fassadensanierungen auch alle Fenster gegen neue ersetzt und vom Verleger in die Fassade einbezogen. In diesem Fall war dies nicht möglich, da in beinahe jedem Stockwerk Fenster unterschiedlicher Bauform und unterschiedlichen Alters verbaut wurden und in Zukunft auch werden.

The picture shows the substructure and the window connection

[Translate to english:] Fensterabschluss

[Translate to english:] Die Anbindung der Fassade an die Fenster musste so gestaltet werden, dass ein Tausch von Fenstern auch künftig ohne großen Aufwand von innen durchgeführt werden kann.

When façades are renovated, it is often the case that all of the windows are replaced with new ones and installed in the façade by a tinsmith. In this case, this was not possible, as nearly every storey has differently designed windows that were installed at different times – which will also be the same in the future. The façade had to be connected to the windows in a way so they can also be exchanged from the inside without great effort in years to come.

Lateral view of the high-rise during the façade renovation. The scaffold around the building can be seen.

[Translate to english:] Stirnseite des Gebäudes

[Translate to english:] Die Stirnseite des Gebäude im Umbau mit dem Baustellengerüst der Fassadenrenovierung.

A close-up of the permanent scaffolding anchor on the Prefa aluminium façade Siding.X

[Translate to english:] Detailansicht eines Gerüstankers der Fassade

[Translate to english:] In die Fassade hat man auch Gerüstdaueranker integriert, die im Falle einer zukünftigen Einrüstung des Gebäudes eine Beschädigung der Fassade verhindern sollen.

Detail view of a permanent scaffolding anchor

[Translate to english:] Detailansicht eines Gerüstankers der Fassade

[Translate to english:] In die Fassade hat man auch Gerüstdaueranker integriert, die im Falle einer zukünftigen Einrüstung des Gebäudes eine Beschädigung der Fassade verhindern sollen.

Country:	Germany
Building, location:	skyscraper, Erftstadt
Category:	reconstruction
Architecture:	Lau Architektur
Installer:	Schröder Bedachungstechnik GmbH
Material:	PREFA Siding.X
Colour:	P.10 light grey

Further information

Text: Carl Bender
Photos: Kristina Prelec, Jens-Uwe Lau, Martin Croce, Schröder Bedachungstechnik, Carsten Friedt

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Close-up of the PREFA rhomboid roof tile with water drops on the surface. The surface of the roof panel is stucco and the colour is anthracite.

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Architect Jens-Uwe Lau: Back to the Future

How PREFA siding.X made the new construction of a high-rise building in Erftstadt from the 70s look modern and timeless – not just now, but in the future as well.

Experts are needed when the air gets “thin”

In the right place at the right time

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A digression for architects and planners

Skyscraper Erftstadt - details