Paul Brown from Swifix looks at the development of new EWI solutions that avoid old timber methods and combine performance with aesthetic appeal
The external wall insulation industry has accelerated in importance for architects, developers, contractors and consumers alike, and has been among the most rapidly growing sectors in the construction industry. However, the progress in techniques and solutions has been proportionately slower, with systems remaining unchanged for decades.
One such practice that has remained unchanged is the fitting and refitting of items back through external wall insulation systems. The growth in external wall insulation (EWI) and solid wall insulation (SWI) installations has increased in recent years; however the way that items are fixed through systems has only recently started to change.
There are still millions of UK properties that can benefit from the application of external wall insulation and therefore it is advisable that this recurring issue for homeowners, tenants, social landlords and building owners of how to fix items to the system should be addressed. It is also equally important for new builds where render finishes have become increasingly popular in recent years, as discerning homeowners are looking for a clean and modern exterior finish.
Current practice dictates that large blocks of timber were fitted before the EWI system was installed, in order to be able to replace items using a screw. The use of timber instantly compromises the insulation system and is not an acceptable method within PAS2030 and PAS2035 regulations, introducing as it does areas of weakness and thereby preventing maximum gains in energy efficiency.
The entire ethos behind EWI is to provide continuous insulation to the whole building, and technical and design teams are determined to avoid cold spots and thermal bridging at critical points on the wall. The use of timber to refit items instantly creates a cold spot – therefore potentially compromising the insulation system and reducing its thermal properties.
Though this has been best practice in the sector for quite some time, it is purely because there has never been a commercially suitable alternative. However, fixing solutions have started to be more available to overcome these issues having been specifically designed and engineered for the refitting of items back through EWI. The fixing system is capable of making a structure completely water-tight. Alongside maximum thermal efficiency and the accompanying savings on annual fuel bills, clients are also provided the assurance of a product which is long-term, non-degradable and flexible to repair and maintain.
It is important to be able to provide fixings that are compatible with the EWI system and will not compromise it in any way to ensure longevity. As well as being able to make available fixings to those who want to attach items to the external walls of their property, months or even years down the line.
Feedback was sought from EWI system designers – they said they welcomed the innovative fixing solutions and felt the products were simple and effective. Fixings are designed to be durable, and have been tested by the BRE for strength, compression and achieved loading up to 130 kg, along with wind and thermal tests. They are also designed to be cleaner and easier to use than the current practice, minimising waste, and to be more sustainable. Providing an aesthetically pleasing appearance to enhance EWI installations, the fixings are compatible with a wide range of exterior finishes including render, brick slip and ‘spar dash’ to enable architects to realise their design without any compromise.
It is important that the re-fixing of items is considered as part of the tender process, with an approved product being used to protect guarantees and warranties. Therefore, it is important to ensure the fixings are incorporated into standard specifications instead of the previous issuing of standard drawings showing timber as a solution. Previously the specification of fixing solutions has fallen between installers and system designers causing ambiguity and confusion in the industry on who is responsible in the event of failure.
However, since the introduction of PAS2030 in 2017, there has been a change in the sector in considering the implications of the solutions currently used and there are now a number of EWI system designers who include the fixings as part of their systems, with many more recommending their use. With the introduction of PAS2035, we hope to see the complete elimination in the use of timber pattresses, and fixing systems becoming best practice.
Paul Brown is managing director and founder of Swifix