Danny Phelan, Sales Manager at Panel Systems, looks at the increasing requirement to upgrade insulation for flat roofs and the effect this has on the whole building performance.
“Flat roofs are widely used throughout the UK for commercial, domestic and public buildings. In the past few years, an increasing number of flat roofs have been upgraded, because of the mandatory requirement to improve the energy efficiency of new and refurbished buildings.
This legislative drive towards the greater energy efficiency of commercial and public buildings and the need to make them more sustainable has led to a greater requirement for more effective insulation.
The design of the roof has a major part to play in a building’s thermal performance, with studies showing that around a quarter of all heat is lost from this area.
Parapets first became widely used on both public and private apartment buildings in the 1960s.
Here, one of the benefits of parapets is that they protect high rise apartments against wind suction, which, over time, can damage flat roof structures. By building these ‘exterior walls’, this reduces the pressure created by wind flow across a flat roof, helping to evenly distribute it across the full surface.
This in turn reduces the suction, or ‘wind-uplift’ on a flat roof and it has been calculated that a 0.4m high parapet can reduce wind pressure on a building by as much as 20 per cent. This is particularly important on roofs that have chipping materials that would be liable to be blown away.
More recently, parapets have reverted back to their original and practical purpose of acting as a fire wall. They help to reduce the spread of flame from one building to another by providing a barrier to radiant heat transfer if fire breaks through the roof membrane. This helps meet Building Regulation B2, designed to prevent the spread of fire through internal linings.
The impact of wind upon design considerations should not be underestimated either, with parapets being one of the most effective means to combat this. British Standard 6399-2 – ‘Loading for buildings: Code of practice for wind loads’ – states that by calculating the effects of wind speed upon a site and dynamic wind pressure on a building’s envelope, a number of factors need to be taken into account, such as terrain, topography and a building’s proposed height and length. It is therefore apparent that a parapet, far from being seen as separate to the main structure of a building, performs a vital role in controlling the effects of wind upon a building.
Taking this into consideration, upstands and parapets are an integral element part of a building’s design, and just like walls, insulating them is vital in order to meet Building Regulations. High performance insulation boards, such as Styroclad can specifically address the issue of heat loss through these types of structures. As upstands and parapets are connected to the main wall and roof of a building via joints, reducing the effects of a thermal bridge from these building elements is vital. Insulating the parapet substantially decreases the amount of heat loss from the building by reducing the chance of cold bridging.
As many flat roofs are found on buildings, such as schools, hospitals and libraries, improving the energy efficiency of these structures is crucial. This can help improve the ratings achieved on Energy Performance Certificates and can also help meet BREEAM requirements. To meet these targets, it is particularly important to insulate upstands and parapets, due to the fact that they are vulnerably exposed to the outside elements and so are affected by low temperatures more so than the normal walls. Without insulating them effectively, warm air can be drawn out of the building as the upstand or parapet acts as a cold sink.
The construction industry was seeking specific products that addressed this issue. As a result of this, we developed a weather-resistant panel that is designed specifically to insulate an upstand or parapet. ‘Styroclad eco’ is a composite panel that features 6mm fibre-cement board bonded to Styrofoam insulation. The facing board is fire rated as Class ‘O’ to building regulation and has Class 1 surface spread of flame to BS476 Part 7. This product can also be used to insulate semi-exposed soffits, providing an extremely versatile solution.
Styroclad eco’s A-rated Styrofoam is manufactured using recycled CO2 as the blowing agent, This is suitable for BREEAM related projects that require a specific environmental rating. It has an Ozone Depletion (ODP) of zero and meets the Code for Sustainable Homes Global Warming Potential (GWP) of one.
A number of office blocks in the South West have recently benefited from Styroclad eco insulation to the upstands, which has helped them meet to BREEAM requirements. The project is part of a development of 4 storey commercial buildings, which also includes a multi-deck car park. The building engineers recognised that there would be an inadequate thermal break between the building and the parapet, with the upstand itself acting as a cold sink, drawing heat from within the building. Styroclad eco helped to reduce its ability to draw heat from the building, which alleviated cold bridging and therefore improved the thermal performance of the building.
Contractors find Styroclad eco easy to install, as it is available in a manageable sheet size at 1200mm x 600mm which makes it simple to handle and user-friendly to cut on site. Many projects use Styroclad eco, because of its excellent environmental credentials.
With the requirements for a well insulated building envelope set to increase as part of the drive towards the greater energy performance of buildings, insulation materials that can meet these higher sustainability criteria are in high demand. Specifiers and contractors need to be able to effectively address the insulation requirements of flat roofs in order to create buildings for the future that are more affordable to run and have long term performance benefits.”
For more information visit the website www.styroclad.co.uk or contact the sales office at Panel Systems on: 0114 249 5635.