First guidance from Masonry Association’s new technical committee raises concerns about the increasing use of zero-compression cavity fire barriers, which it believes present a foreseeable long-term life-safety risk
The initial technical note (TN-01/26), produced by the cross-sector committee, argues that while zero-compression cavity barriers may achieve compliance in laboratory fire testing, buildings are not static systems. Structural frame shortening caused by creep and shrinkage, brickwork settlement, mortar movement, thermal expansion and construction tolerances can all increase cavity dimensions over time, leading to small gaps in barriers that may allow fire and hot gases to bypass the intended line of defence.
Concealed risk
The committee states that barriers installed without positive compression rely entirely on perfect geometry at the point of installation. As building movement occurs, gaps of even just a few millimetres may permit flames and smoke to pass through.
Because these interfaces are concealed once construction is complete, such failures are not detectable through routine inspection, creating what the committee describes as significant life-safety, liability and reputational risks.
The guidance argues that fire-safety performance must be considered over the full life of a building rather than solely at the point of laboratory testing. It recommends horizontal and vertical cavity fire barriers are installed with compression – with a nominal minimum preload of 5mm unless greater compression is justified by manufacturer testing – to maintain long-term contact and integrity under movement conditions.
Strengthening technical leadership
The new technical committee has been established to strengthen the Association’s technical leadership and with an aim of raising standards across masonry construction. Chaired by Association chairman Keith Aldis, the committee brings together senior technical specialists from across the masonry supply chain, including brick and component manufacturers, fire barrier and insulation suppliers, facade contractors, structural engineers, warranty providers and training bodies.
The cavity barrier note is described as the first in a broader programme of work focused on long-term fire performance and lifecycle safety in masonry construction.
Looking ahead
Aldis said he believes manufacturers will support the move, noting that as cavity widths increase to accommodate thicker insulation, ensuring reliable barrier performance will become increasingly critical.
While acknowledging that post-Grenfell reforms have strengthened oversight and accountability, the Association argues that further technical refinements to detailing and specification could help reduce risk proactively, rather than relying on reactive change following future failures.
Aldis added that the committee is keen to engage with standards bodies on the issue.
Its next area of focus will be the use of non-stainless-steel fixings in stone cladding systems.
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