The solution for this project required all parties to think differently. The hospital had plans to extend upwards in the future, however a temporary roof system would not necessarily provide the best waterproofing coverage. In addition as part of the design, Southampton General wished to include a photovoltaic system that could be used straight away and also be re-used for the roof extension in years to come.
After thoughtful consideration, an inverted roof was selected for high-performance waterproofing, whilst allowing for easy access and maintenance by the facilities management team. The easy access points would in turn be very helpful for maintaining the photovoltaic system in the future.
Garland Approved Contractor, Warner Contracting, was assigned to the project and once the new concrete deck had cured, the Garland bituminous membrane system was installed. Using the StressPly Evolution fully bonded underlay and StressPly Flex cap sheet, the bespoke system included 200mm of XPS thermal insulation to achieve the required 0.15W/m2K thermal performance for a new build construction. Finally, over 100 tonnes of ballast was hoisted onto the 900m2 roof, providing a secure platform for the PV system and access walkways.
Warner Contracting also constructed plywood parapet upstands to cover the building’s steel frame, and built to a height that meant a perimeter safety handrail was not required. The plywood upstands would not allow for an open flame, torch-on product, so were encapsulated using Garland’s self-adhesive StressPly Flex SA, conforming to Safe2Torch guidance as outlined by the NFRC.
