HEAVYSIDE SPECIAL: ROOFING
HOW TO BUILD A RESILIENT ROOF
Carl Bailey, regional technical manager for Elevate, on the urgent need to create resilient roofs, including the critical roofing components and the benefits of an EPDM membrane.
T
he need for resilient roofing has never been more important. As the impact of climate change takes hold, it is crucial that a roof protects against increasingly severe weather, including extreme temperature change, rain, hail and wind. For the owners of public sector buildings and their local communities, roof resilience means less disruption to daily life. The risk of any roof damage is minimised, reducing potential costs and downtime, and enabling essential services provided by hospitals and schools to continue. Another important driver for a resilient roof is futureproofing. If a building needs to extend or adapt, then it may have to accommodate new plant, service penetrations and equipment such as solar panels. A robust roof covering should enable these types of works to be delivered efficiently, with minimal disruption and assured weatherproofing for many years after the installation of the product.
Weathering the storm A resilient roof relies on durable components and a robust design. Combined, these factors must create a system which is resistant to all types of extreme weather, moderate movement cycles, and any impact on the roof from a falling object. The system should also allow any future maintenance or repair work to be carried out quickly and effectively.
The waterproofing membrane is a crucial component in the system and must provide the attributes needed to ensure resilience. Specifying an EPDM single-ply membrane is a highly effective solution that will meet these requirements and can be used for flat and low slope roofs on all types of building. Made from a synthetic rubber compound, EPDM membranes are highly flexible and can be elongated by more than 300% without any detriment. This allows them to return to their original shape and performance after severe weather and remain stable for decades. A chemically inert material, EPDM has a low environmental impact and does not contain any plasticiser. It is also resistant to factors that can
accelerate wear and tear over time such as UV, heat, hail and building movements. This durability means that the membrane can accommodate rooftop additions such as solar panels, minimising the potential for any damage during the install. If solar panels do need to be retrofitted, an EPDM membrane provides a further benefit.
Installing a resilient roof The specified membrane must be installed to the right standards to ensure a resilient roof that performs as expected. All roofs are different so many factors need to be considered prior to selecting the membrane attachment system. For an EPDM membrane, a mechanically attached system can provide a fast and cost- effective method, especially for steel or wooden decks. It is suited to large, open roof areas with few penetration details, such as warehouses. The RubberGard EPDM system for example, is mechanically attached using a non-penetrating system. QuickSeam Reinforced Mechanical Attachment (RMA) strips are secured to the structural deck. Large panels of the RubberGard EPDM waterproofing membrane will then be bonded to the framework of self-adhesive strips, meaning no fasteners are required to penetrate the waterproofing membrane. The positions of the mechanical attachment strips will be calculated based on the building’s location and height, exposure level, deck type and fastening system to resist wind load.
Another option, depending on the load- bearing capacity of the roof deck and structure, is to loosely lay the EPDM membrane over the substrate and securely hold it in place using approved ballast such as stones or pavers. This will require extra equipment to move the ballast but overall, can provide another quick installation that can be carried out in all weather conditions. The most versatile attachment system is the
fully adhered system, which is suitable for smaller roof areas, unusual roof shapes and more complex penetrations.
The substrate onto which the EPDM membrane is installed must be sufficiently
November 2023
www.buildersmerchantsjournal.net
durable for the roof’s life and anticipated functions. If the EPDM membrane is installed over insulation, an insulation material with a high compressive strength should be used to prevent deformation from foot traffic.
The use of rigid PIR (polyisocyanurate) foam insulation is recommended for roofs where maintenance access will be required throughout the roof’s service life. Greater resistance can be achieved using a high-density cover board on top of the insulation package.
High density cover boards are ideal for a fully adhered attachment system where the insulation layer is not compatible with the adhesives. Non-combustible gypsum boards provide a durable option and are often required to achieve the higher ratings required on FM- Global projects.
Controlling condensation within the roof system is another important consideration. A suitable air and vapour control layer (AVCL) should be selected based on the temperature and relative humidity within the building.
Technical advice
When planning a roof project, it is recommended to take a ‘system approach.’ The system should be decided in conjunction with technical advice from the EPDM membrane manufacturer and applied in accordance with their guidelines. Once the system is approved by the technical services team, and executed by the trained licensed contractor, a long-term warranty can be provided for peace of mind.
Benefits for all
Climate change poses many risks for businesses and public sector organisations are no exception. As the prospect of more unpredictable and severe weather continues, it is essential that buildings are strong enough to cope. As the first line of defence, the roof has a crucial role to play. A robust design and the right roofing system will ensure a resilient structure that delivers benefits for building owners, occupiers and visitors. BMJ
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