The historic Twyford Water Works is a unique preserved Edwardian pumping station situated in the heart of Hampshire. The building, which is owned by Southern Water Plc, was bestowed the status of a Scheduled Ancient Monument in 1973, which is given to only a small number of nationally important historic buildings that are judged to be important enough to have this extra legal protection.
The Twyford Water Works Boiler House houses three Babcok and Wilcox boilers, which form the last complete set of water tube boilers that survive in the UK. The roof of this building consists of twin pitched metal roofs with barrel ridge sections which are separated by a central gutter. The black paint/coating that had been applied to the roofs was starting to peel and flake away, exposing the underlying metal to the elements and some rusting had started to occur.
The client turned to Williams Roofing Contractors Ltd, a Polyroof approved contractor, to provide a solution that not only would rejuvenate and protect the roof but would also meet the strict criteria associated with such a historic building. A survey of the roof was carried out by Polyroof Technical Services which identified all key issues and formed the basis of a bespoke specification that included a thorough set of recommendations to ensure that both the client's and English Heritage's needs were met.
Polyroof's recommendation for the refurbishment was the BBA-approved Elastex 20 Year System. Elastex is able to form a permanent bond to virtually all types of roofing metals and coatings, meaning that the system is installed without the need for costly and disruptive strip-and-replace works - something that would not have been practicable on a building with Scheduled Ancient Monument Status.
Following the preparation of the surfaces Elastex was applied to all pitched, barrel and gutter sections of the building's roof to form an entirely seamless, flexible and waterproof membrane. In order to replicate the look of the old roof a special Black Colour Finish system was applied over the Elastex membrane - resulting in a refurbishment that was entirely sympathetic to the building. Even the protruding bolt heads, which may have posed a difficult challenge for an alternative waterproofing system, were retained and encapsulated to make fully weatherproof details.
After completing the Boiler House roof refurbishment, Williams Roofing Contractors Ltd subsequently used Polyroof's advanced liquid systems to waterproof the flat roof and gutter areas in addition to separately renewing the slatework, rooflights and lead work - all to English Heritage's stringent conservation specification.
Upon completion of the refurbishment, English Heritage said:
"The repairs to the roof of the pumping station have made a great contribution to preserving the significance of the asset by making the building watertight and protecting both the building and the equipment housed within from decay.
The standards of workmanship shown throughout the project, particularly in relation to the roofing works undertaken by Williams Roofing Contractors, were of the highest order."