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 FI Pro member-only event to better understand:
• Why has this issue 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.
Thank you to everyone who joined the Members’ Technical Meeting on Open State Cavity Barriers and Cold Smoke Propagation. A special thanks to all Facade Intelligence Members who contributed to the research and took part in the professional discussion — your insights continue to shape the depth and relevance of our shared knowledge.
Kevin Blake – AIM
Chris Mort – SideRise
James Davies – Unite Facades
Tony Ryan – SideRise
Camille Destress – BB7
Craig Scott – Century Facades
Chris Jones – Building Standards Consultancy, Nucleus Compliance Group
Nigel Dyer – Clerk of Works
Clare Fenton – Wates
Gabriel Pierazzini – Kier
Joshua Tudor – Clerk of Works
Geir Jensen – FSS AS
James Philpot – FK Group
And a big thank you to Eugene Korch (IAST) for preparing and presenting this complex topic.
The recording is now available on Facade Intelligence for Professional Members.
As one of the key takeaways from the meeting, we’ll begin developing an Engineering Bulletin on Open State Cavity Barriers and Cold Smoke Propagation. If you’re interested in contributing or joining the technical committee, please contact us at members@iast.uk.