Polyroof’s ultra-low odour, sustainable liquid applied membrane, Protec Evolve, was specified by Designed Roof Systems Ltd for the refurbishment of Stringers Department Store. Boasting exceptional performance benefits, including RapidCure technology for extremely fast application, as well as being bolstered with a BBA durability rating of at least 30 years, Protec Evolve is ideal for installation within sensitive environments, futureproofing existing roof structures for many more years to come.
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Background
Stringers Department Store is one of only two remaining independent department stores in the United Kingdom. Since its inception in 1852 as a drapery store, Stringers has been run by three generations of the Clarke family since 1957, providing customers of Fylde and beyond with the very best contemporary shopping experience possible. Nestled in the heart of Lytham, Stringers endeavours to be a leading destination within this idyllic seaside town for beautifully curated fashion, home, and lifestyle items, priding themselves on cultivating lasting relationships with their clientele.
The Challenge
When it became apparent that the roof had succumbed to water ingress as a result of persistent leakage issues, Designed Roof Systems Ltd were approached by the owners of Stringers to propose a suitable solution, who in turn sought the expertise of Polyroof. Upon further inspection from both Polyroof and Designed Roof Systems, it became clear that the multiple aged pitched tiled roofs were the root cause of the problem, being in serious need of renovation. Additionally, due to a change in use of the store’s top floor, from commercial to residential units, this further heightened the need for prompt restoration of the roof structure to ensure that the new flats would be fully waterproofed.
Following the initial site inspection, the Polyroof technical team created a bespoke specification that recommended the installation of a full Polyroof built-up-roof (BUR) solution to provide a waterproof, thermally efficient roofing system to the structure’s three roof areas. One of the many benefits to collaborating with Polyroof on BUR projects is the single source specification solution available to our network of approved contractors, covering the entire project timeline, ultimately streamlining the overall process and helping to maximise operational efficiency. Wind uplift calculations were carried out by the Polyroof technical team in accordance with the requirements of BS EN 1991-1-4:2005 + A1:2010, which ensured that the roof design met wind load requirements, helping to achieve a sound, secure structure. The close geographical proximity to the coastline subjects the building to increased risk of wind, thus necessitating the wind uplift calculations.
There were a number of challenges and complex detailing highlighted in the Stringers project specification, which would ultimately require systematic collaboration and communication to ensure the project was executed seamlessly and efficiently. The main challenge was in relation to the multiple types of substrate present. Out of the three roof areas included in the project’s scope, two areas consisted of timber and one comprised of structural metal. This mean Designed Roof Systems had to ensure the specified solution was suitable for both substrates. Both were firstly primed with Polyroof SA Primer before the application of the Polyroof SA Vapour Barrier (AVCL), thus preparing the roof for the installation of the cut-to-falls scheme. Utilising Polyroof’s Cut-To-Falls Insulation, this enabled the contractors to curate the required falls to help direct any water towards the roof’s drainage system. The inclusion of the cut-to-falls insulation also worked to achieve the required U-Values according to building regulations, which in the case of the Stringers project was 0.15 W/m 2K. Prior to the application of the Polyroof SA Sand-Faced Carrier Layer and Protec Evolve System, insulation and new 18mm plywood were fixed to the inner and top faces of the parapet wall detail, following which a metal capping was installed to create a fully weatherproof detail.
The Solution
Protec Evolve was specified owing to its array of performance benefits, namely its extremely low odour during application. This was of paramount importance for the client as the department store remained open for the duration of the project, therefore, the risk of disruption to commercial operations was high, which had the potential to impact footfall and subsequent revenue. Protec Evolve provides high performing, long-lasting waterproofing to a wide range of refurbishment and new-build applications, being highly versatile and compatible with numerous surfaces. Complete with RapidCure technology for extremely fast application, curing in as little as 30 minutes, Protec Evolve is ideal for installation where contractors are bound by time constraints. Due to the live operational environment within the department store, works needed to be completed quickly so that normal service could resume promptly. Additionally, owing to the unpredictable autumnal weather conditions during the installation, with torrential rainfall and high winds having the potential to disrupt the projece timeline, the fast-curing nature of the system meant Designed Roof Systems were able to apply the membrane around periods of bad weather.
When it came to terminating the system at the various abutment details, special care had to be taken to make certain that each were terminated correctly and fully waterproofed. Regarding the abutments to flashings, Designed Roof Systems dressed the Protec Evolve System underneath the cover flashing, which was installed at the minimum upstand height of 150mm above the roof’s finished surface, in compliance with building regulations. A similar approach was taken in relation to the wall abutment to cladding, whereby the system was terminated behind the abutment with cladding subsequently fitted upon completion of works to provide a fully weatherproof detail. Where the application area abutted the pitched tiled roofs that were also present atop of the structure, the liquid waterproofing membrane was taken up the pitched roof by a minimum of 150mm (vertical height) above the finished surface of the flat roof and 300mm underneath the tiles.
Another complex detail that Designed Roof Systems had to contend with, was the two large rooflights that formed part of the upper roof level’s design. To ensure this detailing was correctly encapsulated by the waterproofing membrane, Protec Evolve was dressed to the rooflight kerbs at an upstand height of 150mm prior to the installation of the rooflights. New Polyroof Pre-Formed GRP Flat Roof Outlets were also fitted to achieve sufficient drainage for the three roof areas, with the waterproofing membrane being dressed and terminated into the outlets.
The Result
The finished result of the flat roofing project at Stringers Department Store exemplifies a successful installation of a full Polyroof BUR system. Designed Roof Systems achieved the client’s refurbishment requirements solution providing optimum thermal performance and design falls to facilitate drainage through the addition of tapered insulation, along with durable, long-term waterproofing with the application of the Protec Evolve System. Despite the various complexities outlined in the specification, Designed Roof Systems fully encapsulated the tricky detailing with the waterproofing membrane, futureproofing the roof structure for many years to come. Their high standard of workmanship was evident through the neatly terminated system to the roof’s outlets. Complete with a BBA durability rating of at least 30 years, this provides added peace of mind for the client that the roof build-up that will protect the structural integrity of the new flats below.
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