INCA, the recognised trade association for the external wall insulation (EWI) industry in the UK, have published a new technical guidance document for the installation of external wall insulation systems incorporating a drained cavity.

The third of 3 key guidance documents published over the last 12 months this industry technical guide defines the installation process, standardises common details, and provides useful information on the various different materials and components that make up a finished system.

The document is intended as a comprehensive introduction to drained cavity EWI systems as the requirements for such systems differ significantly to those of other EWI methodologies.

Drained cavity systems are specifically designed for projects within the UK which involve the application of an external wall insulation system to a frame structure (timber or steel frame) and for which the purpose of use is solely residential and are a requirement of building warranty companies. But the introduction of a cavity within an EWI system presents many challenges and essential complex detailing relating to the spread of fire and / or smoke and the adequate tracking of moisture should the system suffer unintended water ingress.

It is of course also essential that a vented drained cavity system has the appropriate third-party certification.

The guide itself covers all aspects of a drained cavity external wall insulation system including:

• An introduction to drained cavity EWI systems
• The different system types and options
• The components specific to these systems
• Links to additional generic guidance and technical documentation relating to EWI systems

Whilst not a full best practice guide this technical guidance document is intended to provide a comprehensive introduction to drained cavity EWI systems and to link to additional documentation to ensure compliance to regulations and to support installation best practice.

John Sparrow, Executive Director of INCA, said:

“INCA and its members are committed to improving standards in EWI through the development of technical guidance and the sharing of best practice. The publication of this new technical guidance document reinforces the fact that INCA members are leading the way in EWI standards and innovation and remain uniquely placed to represent the industry by delivering the highest quality and service for clients.”

Jane Wiltshire, Company Secretary for INCA added:

“INCA members are required to meet a strict membership criteria which, alongside proven experience and a commitment to best practice, includes a robust training plan, a formal quality management system and an accredited health and safety program – all designed to give clients using an INCA member the confidence that they are working with a highly reputable organisation that meet the recognised standards of competence.”

“The development of this guide demonstrates that INCA and its members are leading the way as the recognised trade association for the EWI industry in the UK. It’s an essential resource for everyone involved in external wall insulation and represents another step forward at a time of significant opportunity across many sectors of the market.”

Additional INCA best practice guides for EWI with brick slip finishes and for those systems incorporating a drained cavity are currently work-in-progress with publication scheduled for H2 2024.