Metro Centre, Gateshead – Sika Liquid Plastics

Metro Centre, Gateshead


Cold Fusion Bonded Built-Up Roof System

Mitie Tilley Roofing Ltd.

This shopping centre in Gateshead is Europe’s largest shopping and leisure centre and employs imaginative redevelopment programmes to keep it at the forefront of retail, competing favourably with new centres throughout Europe. In 1981 the area was designated by the Government as one of the first Enterprise Zones in the UK. This gave rise to the opportunity to claim 100% capital allowance on building work, few planning restrictions, and a rate free status until 1991. More importantly, it helped the centre become economically viable. The concept, planning, and design of this shopping centre were essentially very simple. The needs of the customer were covered in every detail. With this in mind, the aim of the original developers was to provide a shopping and leisure centre that combined the best of North American innovation with all the lessons learnt from centuries of European shopping tradition. The original roof construction of the building was a metal deck with vapour barrier, cork insulation, and polyester based felts – all bonded in hot bitumen and dressed with limestone chippings.

The Challenge
The building is now over 22 years old and the roof is currently undergoing an extensive period of refurbishment expected to last for approximately six years. The building had been experiencing leaks, a problem which was exacerbated by the numerous changes in plant installations on the roof. The original felt waterproofing system had reached the end of its working life and a new system was required that would keep the building watertight, help comply with current building regulations, and bring the insulation standards up to Part L requirements. Because of the large amount of plant and protrusions on the roof, a single ply product was deemed unsuitable. The client also didn’t want to return to bituminous felts; therefore a seamless, liquid applied membrane was sought. Furthermore the new system must not only cater for existing details but also be able to adapt to fit all future plant installations whilst maintaining its guarantee. The client had also banned all hot works from the roof.

The Solution
A Cold Fusion Bonded Built-Up Roofing System from Sika Liquid Plastics was specified for the project. The full system consists of 40mm Decotherm insulation, a Carrier Membrane, and a seamless Decothane Gamma 20 waterproof ‘cap sheet’ in Slate Grey. The system is adhered using Sika Liquid Plastics’ revolutionary cold fusion adhesive – Decostik®. All internal gutters were also fully waterproofed.

Phase 1 of the project was to be completed within 20 weeks without any interruption to the stores trading below. This meant that over 300 tonnes of chippings had to be scabbled and removed from the roof before 10 am each day. During the waterproofing over 100 pieces of plant had to be disconnected, lifted, and refitted, and over 500 protrusions had to be encapsulated. All of this was completed on time with two 12-man teams working on different sections of the roof.

Sika Liquid Plastics’ Technical Teams provided full support throughout the project to help ensure it was completed on time and to the high standards expected. Technical Field Support personnel were on site on a weekly basis throughout the installation process to ensure that the application was fully documented and that any issues that may have arisen on site were addressed quickly and in line with Sika Liquid Plastics’ recommendations. Detailed site reports were then presented to the client so that they had full visibility of the progress of the project. Regular meetings also took place between Sika Liquid Plastics’ Technical Team, the Area Sales Manager, the contractor, and the client.

The Benefits
The Sika Liquid Plastics system was chosen for its completely seamless membrane and because of its proven track record of successful applications. The Decothane membrane can also be easily applied around all protrusions and detail areas without the need for countless jointing. Furthermore, the full system is completely cold applied, thus eliminating the need for any heat or naked flame on the roof, which helped to meet the client’s main stipulation of a heat free application.

Sika Liquid Plastics’ Decothane systems have all been successfully tested to the highest fire ratings in the world – these tests represent the most stringent fire tests available and include ENV 1187:2002 test methods 1, 2, 3, and 4.

In addition to these performance benefits, Decothane has a proven track record of its guaranteed life being extended by a minimum of 10 years at the end of the initial design period. This process can be repeated time and time again and offers huge potential life cycle cost savings over the building’s lifetime.

Once installed the complete system is guaranteed to last for at least 20 years and has also achieved the world’s first BBA certificate for a cold applied built-up roof system. The client was so impressed with the product and its application that phase 2 of the project has now been awarded.