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Kemper Systems helps with refurbishment at zoo, airport and waterfront building

21 August 2015

Air traffic control tower at Liverpool Airport

The Royal Liver Building, John Lennon Airport and Dudley Zoo have something in common: they’ve all recently been refurbished. Here’s the inside story.

They’re three very different locations: the Royal Liverpool Building is one of the city’s ‘Three Graces’ and an iconic waterfront landmark; Liverpool John Lennon Airport relies on its air traffic control tower to ensure it remains disruption-free, 24/7; and the Dudley Zoological Gardens (DZG) is known for its 12 modernist Tecton buildings.

What gives these buildings something in common? Simply, all three needed some form of maintenance. The Liver Building’s distinctive cupolas needed refurbishment in time for a celebratory flotilla. At the airport’s control tower, wear-and-tear demanded the installation of a new roof without disruption. And at the zoo, the Tecton buildings needed restoration with cold liquid-applied waterproofing membranes.

The Liver Building is a particularly imposing building, located at Pier Head. At 90m (300ft) in height, it was completed in 1911 and overlooks the River Mersey. The building’s façades are crowned by a cupola in each corner, each forming the roof of a feature boardroom office below. The huge clock towers either side of the building mirror this pattern, with a ‘mini’ cupola on each of their four corners. All 12 cupolas direct the eye upwards to the summit of the building where a verdigris Liver Bird perches eternally on each of the final, central cupolas.

Meanwhile, the airport may rely on its control tower’s round-the-clock operation, but Robin Hood Doncaster Sheffield Airport also receives vital data from a transmitter located on the roof. This demanding environment meant that the roof refurbishment had to be carried out without any disturbance to air traffic controllers, who must be able to concentrate fully at all times.

At DZG, the buildings designed by Bethold Lubetkin and his Tecton practice in the ‘30s, are the world's largest single collection of Tecton buildings. Over the years, trends in zoo best practice have meant some structures are no longer used as enclosures.

Time has caused wear-and-tear too: the Tectons were put on the World Monuments Fund’s watch-list of world-class buildings threatened by neglect, demolition or disaster in 2010, leading to the current lottery-funded project to preserve and protect them. Among the Grade I and Grade II Tecton structures are the entrance canopy and ticket kiosks, the concession stands and the ‘Bear Ravine’.

In order to find solutions to their maintenance needs, those managing all three structures separately turned to Kemper System, the UK arm of IBG Construction Chemicals Group - a multinational waterproofing and coatings business with operations across Europe, North America and the Far East.

Although Kemper System has been established in the UK for more than 20 years, its initial presence was through large appointed contractors supplied direct from our manufacturing facilities in Germany. In 1997 Kemper System established a UK head office and distribution centre in Warrington, with a dedicated staff including distribution, customer support and technical services, and with a national sales operation supporting contractors and specifiers in the UK.

For the Liver Building, Kemper System’s 1K-PUR cold liquid-applied waterproofing system was selected to complete the scheme. The challenge lies in the fact that the cupolas are made of concrete and have been protected by various waterproofing systems over the years but water ingress was becoming an issue and in some areas the concrete was failing and had to be repaired to return the surface to its original domed shape.

Main contractor Quadriga appointed roofing contractor K Pendlebury & Sons to work at height on the roofs in an exposed waterfront location. “Scaffolding was erected on a small area of the roof at a time and an upgrade to localised areas of the roof beneath each cupola, along with a larger stretch on the Strand elevation, was incorporated into the scheme to capitalise on the accessibility we had to those locations while the scaffolding was in place,” said Neilan Symondson from Pendlebury.

“For these areas, we installed an inverted insulated roof build up, using Kemper System’s V210 cold applied waterproofing system to waterproof the substrate, followed by insulation and then paving.

“The Kemperol 1K-PUR we used for the cupolas works in the same way, with a combination of liquid resin and reinforcement fleece, but it is much more viscous that the Kemperol V210, making it more suitable for the cupolas’ vertical surfaces.”

Pendlebury selected the Kemperol 1K-PUR systems following trials carried out prior to commencing the project to ascertain the best approach to delivering the project with the level of finish required by the building’s management company, CBRE, and English Heritage while managing the time constraints of the project.

The challenging weather conditions of the building’s waterfront location and the need to identify a system that was suitable for the varying surfaces on and around the cupolas also influenced the specification. The method of fleece application and ease of use of the Kemperol system was ideally suited to meeting these criteria on a scheme that involved working up to 14 storeys high.

The installation team began the restoration of each cupola by repairing each concrete structure using Kemper System’s primer mixed with quartz sand to make a mortar that could be used to build up the eroded areas.

The large cupolas have a 2m high vertical surface before the structure starts to curve and gradually become flat over the top. Pendlebury used a combination of Kemper System’s EP5 primer and quartz sand to create a key on the substrate before applying the liquid Kemperol 1K-PUR resin with brushes and rollers.

Kemper System’s 120g reinforcement fleece, cut to size and shape on site, was then laid onto the wet resin. Finally, further resin was immediately applied over the top to allow complete saturation of the reinforcement fleece in a single wet-on-wet process to provide a totally seamless, monolithic membrane.

For the larger cupolas, the scheme also involved scroll features and termination details and the installation team also painstaking applied the system around the solid granite mini scroll features that surround each of the smaller cupolas.

CBRE’s Simon Hepple said: “In terms of surface area, the Royal Liver Building scheme wasn’t large but it was extremely challenging and required a specialist approach and careful product selection. “Kemper System’s Kemperol 1K-PUR was ideal for this project.”


At Liverpool John Lennon Airport, the demanding environment meant the roof refurbishment had to be carried out without any disturbance to air traffic controllers, who must be able to concentrate fully at all times. Roofing contractor, W Swindells & Son Roofing selected Kemper System’s odourless Kemperol 2K-PUR cold applied liquid membrane to address these requirements.

Said John Swindells from W Swindells & Son: “Nuisance odours from a solvent-based or low odour system could have been distracting for the air traffic controllers. We also needed to consider noise levels as the air traffic controllers need to be able to talk to the flight teams in the aircraft, so a liquid system that can simply be applied using rollers and brushes was suitable.”

The air traffic control tower roof refurbishment required the W Swindells & Son team to work at height in an exposed location with limited access and strict security procedures.

“Each day the installation team had to undergo full airport security checks to work air-side and the only way to access the tower’s roof was through the control room itself. Once again, the use of a cold-applied liquid system met these challenges: the use of hot works would have created noise and odours as well as involving carrying cumbersome equipment and gas bottles through the control room.

“With Kemperol 2K-PUR, we just needed to take manageable sized sealed containers of liquid resin through the control room to the roof, along with the reinforcement fleece and rollers,” said Swindell.

The control tower’s existing roof surface was bitumen which hadn’t been replaced since the building was constructed. W Swindells & Son overlaid the existing substrate with Kemperol 2K-PUR waterproofing system in a single wet-on-wet process.

After cleaning the substrate, the installation team applied Kemper System’s D Primer which was left to cure before application of the liquid membrane began.

The Kemperol 2K-PUR resin was applied section-by-section to the roof using rollers. The flexible reinforcement fleece was cut to size and shape onsite and laid onto the wet resin. The installation team then immediately applied more resin to fully saturate the fleece removing air bubbles or creases with the rollers. The resin then cured to form a seamless, durable and U/V stable monolithic membrane.

Swindell said: “The control tower roof is a dodecagon shape with a hexagon structure in the centre. The surface area may be relatively small, but there were significant challenges in terms of details and working restrictions.

“We had to cut the fleece to meet the exact angles of the roof on both sides, creating flashings by bringing the resin and the fleece up the parapet wall on one side and up the central structure on the other. We also had to accommodate numerous supports for the existing handrail that runs around the perimeter of the roof and six existing ventilation outlets.”

Most challenging of all, the contractor had to complete the works without interrupting the line-of-sight signal transmitted from the rooftop satellite to Robin Hood Doncaster Sheffield Airport.

Once the new roof waterproofing system had been installed, W Swindells & Son created a non-slip maintenance walkway by applying a central strip of Kemper System’s Kemperdur TC surfacing on the roof along with anthracite-coloured quartz aggregate as the wearing course. This finish was also applied to the section of the roof where access is gained from the control room.

Swindell adds: “The control tower at the airport may have been a relatively small roof but it was a challenging project and using Kemperol 2K-PUR really helped us address the challenges.”


Meanwhile, at DZG’s a main priority of the refurbishment programme is to protect the structures from water and environmental damage owing to rainfall, which led to the specification of Kemper System’s Kemperol cold liquid-applied waterproofing systems.

“Our Kemperol waterproofing products can be applied to the exact contours of the existing prepared concrete substrate in a single process,” says Stuart Hicks from Kemper System. “They cure to form a monolithic membrane that is chemically bonded to the structure, providing an ideal base for the decorative and slip-resistant quartz aggregates chosen to match the look of the original structures.

“The Kemperol system and aggregates used for the entrance canopy, kiosks and Bear Ravine provide the least obtrusive solution to protecting for the structures without significant changes to their appearance.”

The entrance canopy consists of five horizontal ‘S’ shapes, creating a wave like ripple that announces the word ‘ZOO’ below. The curved shapes catch rainfall, which makes the structure vulnerable to standing water and Kemper System’s Kemperol 2K-PUR waterproofing system was ideal for following the exact contours of each curve to protect the structure.

Specialist contractor, Dent Roofing, was tasked with carrying out this aspect of the project, installing the Kemperol system to two kiosks at a time in a phased programme to enable the Zoo to keep the remaining two kiosks operational.

Dent Roofing began the installation by applying Kempertec EP5 primer to the bare prepared substrate, followed by the Kemperol resin. The resin saturates a reinforcement fleece in a single wet-on-wet process and cures to form a seamless, monolithic membrane that remains permanently elastic and is UV stable.

The design of the Bear Ravine includes a central bear pit with a raised walkway and viewing platform – accessed by a set of concrete stairs – that also forms a partial roof. There is also a viewing pier that extends out at a right angle beneath the main walkway.

For this structure, a quartz aggregate was scattered onto the wet primer to create a key for the waterproofing membrane and Kemper System’s Kemperol 2K-PUR solvent-free system was used.
The Kemperol 2K-PUR was applied using the same methodology with resin, followed by 200g fleece and more resin, in a single wet-on-wet process.

Julian Dent from Dent Roofing says: “The liquid Kemperol system is ideal for following the individual contours of the concrete surface and we simply used smaller brushes to apply the resin to awkward corners.”

Once the waterproofing system was complete, Dent Roofing applied a quartz aggregate to create a non-slip surface. The team then moved on to the Bear Ravine’s concession stand, mixing a paste of primer and resin for application around the outside edge of the roof to ensure that there was no ‘run on’ of wet resin. The Kemperol 2K-PUR system was then applied in the conventional resin-fleece-resin sequence with decorative quartz aggregate.

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