EXTERIORS
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Fix project performance and aesthetics
Mark Newell of EJOT highlights how some of the latest developments in fixings and profiles are enhancing system performance and aesthetics
together, so it is important to understand how seemingly minor design features in EWI attachment products help to optimise a system’s performance.
Secure anchoring and maximising visual appeal
ETICS profiles perform a key role in the durability and performance of EWI systems as the corner bead angle and frame seal bead show here
E
Anchor marks visible on the rendered facade of a property treated with an external wall insulation system
xternal wall insulation (EWI) systems, which we also refer to as ETICS, are playing a crucial role in upgrading the thermal performance of UK homes and other non-domestic buildings. This is important not only in terms of reducing the built environment’s overall carbon emissions, but also for enabling homeowners and building managers to reduce heating costs. Technical innovation is undoubtedly driving ever higher performance possibilities from EWI systems, most notably in terms of thermal insulation levels, but also longevity and aesthetics. This means systems providers are continuously raising the bar, giving architects and specifiers ever more viable refurbishment routes for poorly performing buildings, and avoiding the need for demolition and replacement with new build. Key to this ever improving performance are the latest generation of fixings and profiles used to attach systems to the building’s existing facade. As with any type of building envelope system, it is only ever as good as the components that hold it all
EWI systems are typically designed with anchors which securely attach insulation to the substrate. Due to the different types of insulation available, including phenolic boards, EPS (expanded polystyrene), XPS (extruded polystyrene) and mineral wool, along with huge variations in the building’s substrate, a range of anchoring approaches has been developed. Their principal design objectives include enabling easy installation using the fewest number of fixings and minimising the potential for thermal bridging. The plastic washer and metal fastener combination that many systems utilise is, therefore, critically important to the long term success of an EWI system. So, it is important to look for ETA (European Technical Assessment) approved products, or those with other credible third-party certifications, for additional assurance when specifying. Today’s advanced EWI systems provide higher levels of thermal insulation by using thicker insulation, held in place by countersunk anchors. Without the right anchoring approach for a thicker layer of insulation, however, there is the potential for weak points in the thermal performance and ‘anchor marks’ to appear on the rendered finish.
This is due to insufficient treatment of the recess in the insulation, resulting from the countersinking process, which often means it is deep filled with render. As a result, the consistency of the insulation is broken, creating a difference in how heat and moisture transfer through the EWI system at those points.
External Envelope_ Cladding & Facades -
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