Andrew Swift, technical advisor for foam sealants supplier ISO-Chemie, offers advice for installers about achieving energy efficiency installations and the benefits of using foam tape sealants for longer last performance.
New regulations coming into force this June aim to improve the technical competency levels of those involved in the fenestration industry but it will remain incumbent upon installers to make sure that the benefits of A-Rated energy efficient windows are not compromised by out-dated installation techniques and poor sealing products.
The energy efficiency and cost effectiveness of A-Rated windows will be drastically reduced by substandard installation – warm air will always look for the most vulnerable point to escape, so it is important that the 10mm or so expansion gap around the frames, cills and walls left after the window’s been fitted is effectively sealed to prevent heat loss and provide long term insulation benefits.
In some instances, the leakage of heat around incorrectly fitted windows can reduce the ‘energy index’ as shown on the British Fenestration Rating Council’s Domestic Window Energy Rating Scheme by three units or more. This can add up to a significant loss when its considered that the average semi-detached house contains more than 16 sq m of glazing and it’s virtually ‘criminal’ that too many window installations are going unchecked or unregulated, leaving a potential legacy of problems that can last for years and cost thousands of pounds to rectify in the long run.
Normally gaps between frame and substrate are left empty, or some uncontrolled volume of spray foam is injected to fill the void before a silicone trim is applied for a smart looking finish. Unfortunately, as expedient as this might be, none of these solutions create a measurable, long term, high performance thermal, acoustic or airtight barrier – silicone usually fails within five years, reducing the U-value of the installed window, ensued by heat loss and further expense on repairs and replacements. What’s more, the Glass and Glazing Federation’s own Good Practice Guide states ‘Finishings (trims etc) should not be used to enhance the weather tightness of the windows and doors’.
Fit and forget
So how is a first class installation achieved? Installers certainly deserve better insulating products to save energy and money for the end user and a new generation of high performance foam sealing tapes, which use ‘smart’ foams impregnated with different substances to create a measurable U-Value as low as 0.6w/m2k, provide good thermal insulation and acoustic sound reduction by up to 44dB.
Although the UK doesn’t yet have proper regulations or recommendations for the installation and sealing of fenestration, mainland Europe does. These include the RAL Window Installation Principals, which state that windows should have three levels of sealing. The outside should be weatherproof but breathable to allow potentially trapped moisture from other ingress areas to escape outwards. The inside should supply an airtight and vapour control seal while the middle area between these should have additional thermal and acoustic insulating properties. This system has excelled in Europe for many years and correctly done offers compliance with the high standards demanded by among others the Passivhaus Institute.
Various manufacturers supply products that can be mixed and matched to produce the three level sealing systems, complying with energy conservation standards, but some like ISO-Chemie supply ‘all-in-one’ solutions that give a similar or better performance depending on the systems/products. These together with the fact that they enhance the aesthetics of fenestration products, can be used in installers’ marketing campaigns to engage customers to secure work, market share and profits.
The future for these ‘fit and forget’ systems is evolving quickly and most now comply with the RAL principals, not only exceeding the requirements of the UK Building Regulations but saving time and money for the installer. So, it’s not just regulations that are changing; consumer demand and the market place that companies like ISO-Chemie supply are also changing, and window installers must move with the times – the writing is on the wall but the solutions are already here to facilitate change and add even more value
