What are insulated cavity closers?
As buildings become more highly insulated, thermal bridging subsequently has a greater impact on heat loss and with building fabric performance requirements becoming tighter than ever, this is an area that is increasingly significant. It is no longer good enough to use make-shift methods around window and door openings with materials that provide inadequate insulation. Insulated cavity closers provide a simple and effective method of dealing with this issue, providing a damp proof barrier and minimising thermal bridging around openings.
What are the issues?
Openings can easily let the construction down if they are not treated so as to minimise thermal bridging. Under the latest Approved Documents to Part L there is a new 2013 Notional Building Specification, which, like its predecessor, uses linear thermal bridging as one of the parameters for achieving compliance.
Linear thermal bridging is the term used to describe the heat loss (psi-value) at junctions between elements and around openings in elements, where there is an interruption in the insulation layer, and this is taken into account when calculating the whole building carbon dioxide emissions, which will determine whether or not the construction is compliant. Quite apart from the issue of compliance, thermal bridging can also produce problems of condensation, which may lead to unsightly mould growth and eventual deterioration of plaster and paintwork.
Cavity closers can maintain a continuous insulated barrier around window and door openings, providing improved psi-values and helping to achieve compliance. It avoids the need for cut bricks, blocks or special reveal blocks, thereby simplifying and speeding up the construction process and saving both money and time spent on site. Cavity closers can either be built in with frames or used to pre-form openings when frames are fitted later, helping to ensure the accuracy of opening sizes
Using a cavity closer with premium performance insulation can yield psi-values significantly better than those assumed in the 2013 Notional Building Specification. These products can not only improve the overall thermal efficiency of the building envelope, they can also provide up to 60 minutes of fire resistance; a particularly important consideration for schools and hospitals. Another benefit is that it can include an integral damp proof barrier, effectively preventing the problems frequently associated with traditional methods of closing cavities and thermal bridging.
Quality of build
Quality of build is increasingly coming under scrutiny and cavity closers are a simple way of making sure that, for some areas at least, ‘as-built’ readily meets ‘design’.
With such an effective and straightforward solution available to improve psi-values, deal with openings and provide assured levels of fire performance, there is no need to try and cobble together some second-rate means of closing cavities, risking both non-compliance and long term problems with condensation. Perhaps most importantly, the overall building envelope performance is not compromised by inadequate construction detailing around junctions and openings, allowing thermal efficiency to be maximised, and making those all-important energy and carbon savings.
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