Upstands and parapets play a crucial role on flat roofs because they distribute wind flow, enhance fire safety and maintain building proportions. Danny Phelan, Sales Manager at Panel Systems, looks at ways of ensuring they also help enhance the thermal performance of a building.
“The history of parapets dates back to the Building Act of 1707, which banned projecting wooden eaves on buildings in Westminster and London labeling them as a fire risk. As an alternative, brick-made walls were built above the roof plane around the perimeter of many buildings’ roofs. Known as parapets, they are now found throughout the UK and can vary from approximately 0.4m in height to several metres.
Parapets are prevalent on inverted roofs because they add a design element to an otherwise aesthetically restricted roof construction. This is because many parapets, especially those constructed in the Georgian era, have been intricately decorated and were a common addition to a building at the time due to the fashion to hide a roof from view at street level.
In modern times, they also serve a more practical purpose as a fire wall by helping 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.
The impact of wind upon design considerations should not be underestimated by building designers. 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 to a building’s design, and just like walls, insulating them is vital in order to meet Building Regulations. High performance insulation, such as that provided by our Styrocladeco range, 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, reducing the effects of thermal bridging from these building elements is vital. Insulating the parapet substantially reduces the amount of heat loss from the building by reducing the chance of cold bridging.
As many flat roofs are found on public sector buildings such as schools, hospitals and libraries, improving the energy efficiency of these structures is crucial. This can help improve the ratings achieved 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 effective insulation, warm air can be drawn out of the building as the upstand or parapet acts as a cold sink.
When we were developing our Styrocladeco range, which has a 6mm fibre cement facing board bonded to 20-150mm thickness insulation, demand from specifiers required an ‘A’ foam option. Our Styrofoam LB-A uses recycled C02 as the blowing agent, making it a useful option for building designers, as it has an Ozone Depletion (ODP) of zero and Global Warming Potential (GWP) of one, which means it helps to achieve an enhanced BREEAM rating.
Our fibre cement facing board is also Class 0 fire rated and has a Class 1 surface spread of flame. The facing board, which is self finished and requires no additional decoration, also provides a dimensionally stable, impact and weather resistant protective exterior to the insulation.
By specifying insulation for upstands and parapets, building designers can ensure that the thermal efficiency of the building is maintained for the long term. The insulation solution must be weather resistant and easy to install, making it an essential component on all flat roofing applications. As energy efficiency legislation on both new-build and refurbishments becomes more stringent, the focus on insulating parapets and upstands looks set to grow in importance.”
Panel Systems is one of the UK’s leading manufacturers of insulation products, composite panels, structural foams and flexible staging systems. For more information, visit the website www.panelsystems.co.uk or call direct on: 0114 249 5635.