Build November_2016

Build Magazine 18 Construction The use of polyurethane foam for insulation of buildings, coupled with building information modelling, can result in smaller heating systems being specified. Regardless, it will certainly cut energy usage, particularly when this is combined with other energy saving measures. The British Urethane Foam Contractors Association (BUFCA) is the national trade association in the UK and a central resource for the application of sprayed and injected polyurethane foam systems. The association comprises polyurethane foam installers and suppliers of sprayed and injected polyurethane systems and equipment. he insulation value of polyurethane foam is amongst the best available as the foam seals all gaps and moulds itself to all contours. It has the ability to provide significant structural strength and it creates its own vapour control layer – essential in today’s highly insulated buildings. Polyurethane foam can be installed for air tightness and to help meet Building Regulations as wall insulation, roof insulation, floor insulation or to fill voids and other areas providing a seamless, thermal insulation barrier. Other jointed systems give rise to a potentially weak point, leading to a significant loss of insulation value. For instance, polyurethane foam can be economically applied to the underside of traditional residential roofs, as well as those constructed from steel, asbestos and aluminium. Systems can be applied to various depths and have K-values in the range of 0.025 - 0.028W/mK. When sprayed to a depth of 100mm, the U-value of a typical roof with 100mm fibreglass at ceiling level is reduced from 0.34W/m²K to 0.16W/m²K bringing the building up to current Building Regulation requirements. This can save the equivalent of more than one tonne of CO2 per annum Polyurethane Foam for Energy-Efficient Buildings, by Leonie Onslow, Executive Director, BUFCA by reducing energy consumption. The two-component liquid system produces a highly-efficient blanket of insulation with a thermal conductivity approximately twice as efficient as fibreglass. It is particularly cost-effective and easy to apply to a wide variety of substrates. Its closed-cell nature renders it very resistant to moisture ingress. Polyurethane foam is not just an insulant – it can be used for stabilisation purposes, for instance to hold tiles in place for a stronger roof structure or to take the place of failing wall ties. The material can often be used when other materials are not suitable. Some of the types of applications are outlined below but actually the material is so versatile that it can be used in many more! For wall insulation, injected polyurethane foam can be used in the cavity to provide a superior performing insulant which also helps to bond the inner and outer leaves providing strength to the building. Air leakage through the cavity can be reduced to zero. Because of the greater thermal performance and the reduced air leakage PU foam outperforms all other forms of cavity fill. Polyurethane foam systems provide the ideal solution for industrial and commercial buildings as large areas can be insulated quickly for insulation and condensation control. Factories, warehouses, exhibition halls, football stadiums and offices can all be insulated. Where buildings have been subject to a change of use spray-applied and injected polyurethane can achieve high U-values outperforming many other insulants. The insulant can be applied to most building substrates and will fill voids which might otherwise be difficult to reach with other materials. Closed cell foams are resistant to driving rain meaning that the material stays dry with no loss of thermal properties. The insulant can help act as a barrier to prevent flood waters from entering the building through the walls. The British Board of Agrément certification approves this insulant for cavity walls in all exposure zones. Closed cell foams which achieve a Class 1 fire rating when tested to BS476 Part 7 are available. Or, where non-Class 1 materials are used on internal applications these must be covered by plasterboard, or a similar thermal barrier. Conversely, open cell polyurethane foams do not have the high insulation properties associated with the closed cell materials, which is a distinct disadvantage if trying to save space. They do not have the same fire performance as closed cell, so they should never be left exposed; they have T