Often, the process of upgrading social housing properties is coordinated with planned maintenance or repairs, and this has certainly been the case for a number of social housing blocks in Halifax. A rolling programme of re-roofing works has seen more than 434 flats – operated by Pennine Housing and refurbished under the Efficiency North Framework – improving both thermal performance with new insulation and water-tightness using a new RubberGard EPDM Single Ply Waterproofing System from Firestone Building Products.
Deciding the spec
While the programme of works is significant, the scheme has not involved an architect because the refurbishment for each block comprises roofing upgrades only. In order to determine the specification, a performance specification was devised for all Efficiency North Framework social housing schemes for Pennine Housing, this was prepared by Pennine Housing’s in-house maintenance department.
The job of selecting a product that could conform to the performance specification fell to roofing contractor, SBS Roofing. The company used its experience of high-rise buildings to select the right approach.
Phil Redfearn from SBS Roofing explains: “Roofing schemes for taller buildings not only involve working at height considerations but, also need to factor in the long-term performance of the waterproofing membrane to minimise maintenance and extend replacement intervals. That calls for a robust system with good compatibility with the substrate and excellent adhesion to avoid uplift. We had used Firestone’s RubberGard EPDM membrane on similar projects before, and knew that it would be: fast to install, reduce time on-site, and suitable as a long-term and cost-effective solution for buildings of various heights.”
SBS worked with the technical team at Firestone to develop the specification and test the chosen system prior to beginning work onsite. Firestone developed a detailed specification to address the performance specification criteria and SBS tested it on isolated sections of each roof to ensure compatibility and anti-uplift.
John McMullan from Firestone comments: “The benefit of a performance spec is that it puts product decision making in the hands of a roofing expert. Working with the supplier in this way ensures that the roofing contractor has all the support required to match the roofing system to the building and, in this case, complete a project with a design life of at least 40 years.”
The first blocks to be re-roofed under the scheme in the Elland area of Halifax were: Calder House, Croft House, Portland House and Coniston House – all six-storey blocks are on the same social housing estate, with an existing mastic asphalt roof.
Whilst the roofs were not yet failing, the decision to install new insulation to improve the buildings’ thermal performance made a warm roof overlay – the most appropriate and best value approach.
PIR insulation board was adhered to the prepared asphalt surface. The Firestone RubberGard EPDM membrane was cut to size prior to installation and adhered directly to the insulation using Firestone’s solvent based contact adhesive. All joins were sealed with a 75mm overlap using Firestone’s QuickSeam Splice Tape.
On each of the four buildings, SBS cut the RubberGard EPDM membrane to form details around a large number of ventilation outlets and penetrations, using Firestone’s QuickSeam FormFlash to ensure that all penetrations were fully sealed and completely waterproof.
The installation challenges at Ladstone Towers and Houghton Towers in Sowerby Bridge were multiplied, due to the fact that the blocks are 14-storeys and 46 metres tall.
However, the warm roof overlay methodology remained the same, with installation of the insulation onto the 650m² felt roofs and the adhered RubberGard EPDM membrane.
Phil from SBS continues: “For the taller blocks, sections of the RubberGard membrane were cut at ground level and the seams were sealed on the roof. Installing smaller sections made it easier for our teams whilst working at height in windy conditions. It also made the membrane more convenient to transport goods to the roof level using the goods hoist that was erected on the outside of the building for the duration works, to prevent any disruption to tenants.”
Works were completed on all six blocks whilst the homes were fully occupied and minimising disruption to tenants was another key factor in the specification.
John explains: “By choosing an EPDM membrane overlay, SBS were able to minimise disruption to tenants by avoiding the need for strip out or any hot works. The durability and proven longevity of EPDM also means that it delivers excellent whole-life costs and low-maintenance benefits for Pennine Housing.”