Member-Only Technical Event

Thursday, 4th November 16:00-17:00 | Online

The Building Safety Regulator has recently raised serious concerns regarding the use of open state cavity barriers around window openings.

As a result, several Gateway 2 applications have been returned for clarification, with specific reference to this issue.

The concern stems from the way open state cavity barriers function.

The intumescent strip within these barriers requires a certain amount of time to react to heat and expand, closing the cavity.

During this short period—before activation—there is potential for cold smoke to propagate through the façade cavity between the cladding and insulation layers.

For this reason, both the Regulator and design stakeholders across the industry have expressed caution over their use, particularly around window perimeters.

However, from the facade engineering standpoint, open state cavity barriers play an important role in maintaining ventilation and drainage within the façade system. The area above window heads is among the most vulnerable zones for rainwater ingress, and restricting ventilation here can introduce new risks.

Join our member-only event to better understand:

• Why this issue has emerged in recent regulatory reviews.

• How open state cavity barriers operate.

• Alternative routes to demonstrating compliance under the Building Safety Act.

• Possible design arrangements/alterations for maintaining compartmentation without compromising drainage and ventilation

This is a member-only event hosted by Facade Intelligence and the Institute for Architectural Science and Technology (IAST).

Please register using the email address linked to your IAST membership to ensure access.