The Park Inn by Radisson is located in the heart of Peterborough. A new waterproofing system was urgently required for the hotel’s high-level flat roof areas, which comprised extensive air conditioning equipment.

The existing single-ply covering had been lifted by the wind due to its reliance on poor quality perimeter fixings, exposing large sections of the underlying structure. Water had penetrated into the main building, filtering into a lift and causing it to short out. The aim was to replace the roof covering with a highly durable solution that could be applied quickly to resolve the issues and prevent any further damage.

The Park Inn by Radisson features 115 rooms for business and leisure travellers. Architects (PS)K Design turned to Kemper System to help design and install a new waterproofing system for the hotel’s high-level flat roof areas.

A PMMA liquid waterproofing solution was specified, ensuring several challenges were overcome. Crucially, the use of a liquid applied system avoided the need for plant to be removed and re-installed resulting in savings of circa £100,000.

The rapid curing solution, which can be applied at temperatures of -5 degrees centigrade, enabled the waterproofing to be quickly and effectively installed around complex detailing and during low winter temperatures meeting the client’s challenging programme requirements. The result is an aesthetic and highly durable roof that was delivered within 11 weeks to programme and well within budget.

Initially, a PVC or EPDM single-ply membrane was considered for the project. Supplied in rolls, these systems would have required the air-conditioning plant to be removed prior to installation, and then re-installed with no guarantee that it would work again. The operational risks of this approach and associated costs, including crane hire, demanded a more effective solution.

Kemperol AC Speed, a cold liquid applied waterproofing system based on rapid curing PMMA resins, was specified as an alternative by the client. The cold-applied system allows same-day application. The waterproofed surface can be walked on after just 35 minutes. Once applied, the solvent-free resin cures to form a seamless, elastomeric waterproof membrane that cannot delaminate, is UV stable, and bonds directly to the substrate.

The liquid waterproofing system was installed by Castle Contractors NW and laid directly onto the majority of the existing, prepared roof covering. A section of the roof required the existing single ply and wet PIR insulation to be removed and replaced with new mechanically fixed Kempertherm SR insulation, with a factory bonded 3mm reinforced facing layer allowing direct application of the Kemperol AC Speed.

The liquid waterproofing enabled all the plant to remain in place saving the client circa £100,000.

Ensuring the highest quality workmanship and driving further efficiencies, the contractor acquired 12, three-tonne bottle jacks to assist with the installation. This enabled the feet of the plant to be lifted and the area underneath to be thoroughly cleaned before applying the PMMA. Once the liquid waterproofing had cured, the feet could be put back within an hour ensuring a quick and efficient solution.

The bottle jacks were also used to lift the ducting which ran along the full length of the roof.

As well as curing quickly, the AC Speed was quick to apply thanks to the use of a roller and a reinforced polyester fleece. This meant the contractors could work efficiently across the whole roof area, including waterproofing around the extensive detailing, which in addition to the air conditioning units, included many outlets and pipe penetrations.

Speed was imperative throughout the project not only to resolve the issues on the roof as quickly as possible but to combat adverse weather conditions. The work took place at the end of 2020 in the cold and snow. In addition to using snow shovels, the contractor connected a hose to a hot water tap to melt the snow and avoid any unnecessary delays. These efforts combined with the fact the PMMA system could be applied at temperatures as low as -5 degrees, ensured the project kept to programme.

The qualities of the PMMA system combined with the contractor’s skills and workmanship ensured all challenges were overcome, saving the client substantial costs and delivering a watertight roof within just 11 weeks.