Alumasc’s Technical Director Mark Gibbs explains what specifiers should be looking for in their chosen EWI system for high-rise and why safe installation is paramount.
Specification for the multi-storey application of External Wall Insulation is very different to that of low-rise projects, with health and safety procedures being a key consideration in the thermal upgrade of high-rise buildings.
EWI is a cost effective method of achieving the thermal and aesthetic upgrade of buildings. EWI has been used in the UK for the refurbishment of high rise projects for over 25 years. The solution is particularly effective for, although not limited to, high-rise social housing schemes of non-traditional or traditional type construction. Condensation, water ingress and the poor thermal performance of many of these blocks has been addressed by specifying EWI, providing a U-Value to comply with current Building Regulations.
EWI System Build-up for High-Rise
To achieve the thermal requirements of the project, the appropriate type of EWI insulation board is mechanically and adhesively fixed to the substrate. A polymer modified reinforcing base coat, incorporating a fibreglass reinforcement mesh, is then applied. Once this has fully cured, there is a choice of finishes ranging from traditional dash or painted renders, to more modern through-coloured silicone renders.
High-rise EWI specification is different to that of low rise because the insulation boards must be adhesively and mechanically fixed. Wind load calculations are essential and the edge zones, external corners and openings require increased mechanical fixings to accommodate higher wind loads. The calculations must always be conducted by Structural Engineering Consultants to ensure structural stability, required performance and system longevity.
Specified EWI systems must be officially accredited and approved for use in high-rise application. A large scale fire test or reaction to fire test is required for the system when used above 18m in height.
As well as through-the-wall square metre rates, there are additional detailing considerations compared to low-rise. These include parapet, lightening conductor, CCTV, external lights, robust window cill details, ground floor entrance areas etc.
It is critical that all the detailing is robust and installed as per specification. Once the wall access is removed any repairs are more difficult and costly to address than for low-rise projects.
Scaffold ties should be fixed in the most practical locations and protected scaffolding is recommended. Alternatively, mast climbers are an economical and faster track option for EWI install but offer less protection to newly installed work. Programming considerations should always allow for weather conditions.
EWI is a cost-effective and energy efficient solution for high-rise blocks allowing for an aesthetic transformation of the building and the surrounding area. Improved thermal performance results in less fuel consumption and therefore less CO2 emissions leading to a typical saving of around 30% on tenants’ heating bills.
For more information on External Wall Insulation click here or please call us on 03335 771 700.