68 RCI 0514

RCI May 2014

FLAT ROOFING & FLEX SYSTEMS Long-term solution to a complex roof area York Castle Museum is one of North Yorkshire’s leading attractions and is on the site of the original York Castle, built by William the Conquer in 1068. The museum was founded in 1938 and is housed in prison buildings which were built on the site of the castle in the 18th Century using ruins from the castle itself. York Museums Trust, an independent charitable trust, manages York Castle Museum, Yorkshire Museum and Gardens, York Art Gallery and York St Mary’s, all of which STS have carried out preservation works on in recent months. The buildings and their contents are owned by the City of York Council, which has agreed to longterm funding of the Trust. Project requirement York Museums Trust approached STS to design, develop and install an appropriate, aesthetically sympathetic solution to prevent water ingress at the York Castle Museum Café, a popular tourist attraction. The building has had a longstanding problem with leaks and water damage and this needed to be rectified in order to prevent any potential loss of business and to meet health and safety requirements. Following inspection, STS discovered that past remedies to the water issues had included inadequate patching using various compounds which had failed to protect against the often harsh Yorkshire weather conditions. Solution STS recommended that a GRP (glass reinforced polyester) roof covering was applied to all external valleys of the York Castle Museum Café, as well as to all of the flat surfaces on the roof to offer extra protection and alleviate all potential water ingress issues. GRP was considered the best solution for this project as it offers exact project specification 068 MAY 2014 RCIMAG.COM By Dave Stone, managing director, Stone Technical Services (STS) Above: New exterior weather board attached to existing bitumen covering and prepped for GRP fibre glass application products including resins, topcoats and preformed trims. It is especially effective in instances such as this at the York Castle Museum Café as it has a flat roof and GRP has been developed with strong, yet versatile, water-proofing properties. It also offers long-term protection, reducing the need for ongoing maintenance and costly repairs. GRP also offers a number of important health and safety benefits as products are cold laid and therefore do not require any form of heat treatment, helping to protect installers and the general public during the project. In addition, this means that they are not subject to the same prohibitive insurance premiums levied at installers using hot-works. Traditionally, flat roofing systems aren’t long lasting and can be prone to water ingress. However, STS’s chosen GRP solution and bespoke installation methods are extremely durable and completely waterproof and can be finished in any colour to be in-line with building aesthetics – vital for historic buildings such as the York Castle Museum Café. Method The roof surface had to be covered in 16mm plysheeting to create new levels on the roof and also new drainage capabilities. In addition this would enable faster water drainage during especially bad weather. This was then coated with fibre glass matting and resin coating which was also applied to all external trims. A final coat of grey top coat resin was applied to achieve a smooth finish. The entire area on the York Castle Museum Café roof was encapsulated into one single, continuous GRP membrane and therefore there are no unsightly seams, joints or welds. The roof is now completely UV resistant and the high-quality roofing system installed by STS should remain leak-free for life. In addition, the new roof system is also eco friendly and is a longterm solution to a complex roof area which was causing major disruption to the museum’s business – the long-term advantages of the flexible system is of paramount importance. www.stonetechnicalgroup.co.uk Above: Existing bitumen covered flat roof section which was failing in multiple places leading to water ingress internally Project issues The main issues to consider for this project were: • Public access – as York Castle Museum Café is a popular tourist attraction it had to remain open and STS’s works had to be unobtrusive. We did this by using discreet access scaffolding with public-facing banners so as not to look unrealistic to the heritage surroundings in the immediate area. • Building aesthetics – York Castle Museum Café is historically significant and its structure dates back hundreds of years. With this type of project, it is vital to take this into account and always use the procedures and materials that best suit the building’s aesthetics. It is also important to consider that the project must be cost effective and any works must be long lasting due to funding issues. STS ensured this was the case by developing a bespoke flat-roof solution using the best products available, as detailed. “The roof surface had to be covered in 16mm ply-sheeting to create new levels on the roof and also new drainage capabilities. In addition this would enable faster water drainage during especially bad weather” Above: Finished GRP application fully water tested and weather tight


RCI May 2014
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