The illbruck i3 sealing system has been used on a refurb project as part of Channel 4’s House Without Bills.
This show documented a renovation project involving a 1930s semi-detached property in Greater Manchester, with the illbruck i3 sealing system selected to deliver airtightness and weather protection. The project team aimed for Passivhaus standards and required a sealing solution that could prevent condensation, and ensure the airtightness level necessary for Passivhaus certification.
The three-layer illbruck i3 sealing system
Unlike traditional methods of window and door sealing that may rely on a single line of sealant, the i3 system utilises a three-layer principle. This approach ensures that the joint is sealed effectively against the weather while remaining permeable to water vapour, preventing the accumulation of interstitial condensation.
The i3 system separates the sealing function into three distinct zones, adhering to illbruck’s “inside tighter than out” principle.
External Seal – provides weather tightness and protection against driving rain, while allowing moisture vapour to escape from within the joint.
Intermediate Seal – provides thermal and acoustic insulation, ensuring the joint does not become a weak point in the building’s thermal envelope.
Internal Seal – provides airtightness and vapour separation, preventing warm, moisture-laden air from the interior entering the joint and causing condensation.
The inclusion of the illbruck i3 Sealing System in Channel 4’s House Without Billsserves as a powerful testament to the product’s technical excellence. It demonstrates that with the correct specification of high-performance materials, even challenging retrofits can achieve exemplary standards of energy efficiency.
To learn more about the illbruck i3 visit: illbruck.com/en-gb/products-systems/innovations/i3-sealing-system/
For more about creating energy-efficient buildings, visit InstallerSHOW, running 23-25 June at the NEC. Free tickets here: forms.reg.buzz/installer-show-2026
