Green Roof Projects 5 STEPS TO INSTALLATION SUCCESS Carl Bailey, Regional Technical Manager for Firestone Building Products (soon to be Elevate), explains how contractors can create a green roof that lasts. As the focus on environmental sustainability increases, so does the demand for green roofs. Homeowners, building owners and developers are beginning to recognise the value a green roof can bring to the environment as well as people and their wider communities. The benefits are vast, including providing natural insulation, enhancing biodiversity, reducing air pollution, improving stormwater management, and mitigating the ‘urban heat island effect’ by returning moisture to the environment through evaporation. There are two main types of green roofs: extensive and intensive. An extensive green roof uses sedum vegetation and is most common on flat roofs as it is lightweight and low maintenance. An intensive green roof is more complex, including trees and shrubs requiring irrigation, fertilisation and more maintenance. To be successful, a green roof installation must combine an effective design, quality waterproofing, and suitable maintenance. So, here is our guide on the key steps to follow and key considerations: 1Engage early in the design process: The climate, local building regulations and building type are just some of the factors that will affect the design of a green roof, including the types of plants and growing substrate. Understanding these elements from the outset is crucial as they will impact the choice of roof build-up, as well as future maintenance. 2Choose an appropriate waterproofing system: There are different waterproofing systems suitable for a green roof and selecting the right one is essential. The membrane must be resistant to root penetration and strong enough to be trafficked when maintenance is required. The RubberGard EPDM and UltraPly TPO membranes, for example, have successfully passed the EN 13948 – resistance to root penetration test – and the FLL root penetration resistant test from the German Landscape Research, Development and Construction Society. An EPDM single-ply membrane which is 1.5mm thick and fully adhered to the substrate provides a robust and highly effective solution. The use of wider panel sizes will limit the number of seams, reducing the risk of any water ingress. Studies have shown that EPDM membranes can last for more than 50 years. Their flexibility can accommodate expansions or contractions due to temperature changes and they don’t contain any chemicals that can affect the membrane’s characteristics over time. EPDM is an inert material, with no harmful chemicals released into the atmosphere during its long service life. It is recognized as safe for rainwater harvesting from roofs for use in nonpotable, domestic use such as running washing machines or flushing toilets. Rooftop vegetation also offers additional protection for an EPDM membrane, further extending its service life. 3Adhere to best practice installation advice: Only install an EPDM single ply roofing system if you are trained and authorised to do so by the manufacturer. A typical installation would involve laying the structural deck to falls to achieve a minimum finished slope as per local requirements and encouraging efficient roof drainage. The deck is primed before placing a vapour control Above: Carl Bailey. layer on top, which will restrict moisture vapour from within the building from rising up into the insulation layer where it could cause damage. An insulation board with a high compression strength will be required with an appropriate thickness to achieve the required roof U-value. This will be adhered to the vapour control layer prior to fully adhering the EPDM single ply roofing membrane with a bonding adhesive. An extensive green roof system, including a protection mat, will then be installed over the EPDM membrane. 4Advise on maintenance: There is no such thing as a zero maintenance green roof. There will be watering guidelines to follow after the installation and an annual soil test should be performed in the spring along with the use of slow-release fertilisers. It is also vital to control weeds as weed killer is not permitted on a green roof. As part of the maintenance plan, a postinstallation inspection should be carried out annually for the first two years. 5Partner with a specialist: Whether you are installing an extensive or intensive green roof, it is important to partner with a specialist provider of roofing waterproofing systems from the earliest opportunity. Their knowledge and technical advice will help to ensure the green roof meets the required specification and is built to last. Contact Holcim Elevate www.holcimelevate.com 34 TC SEPTEMBER <strong>2022</strong>
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