Construction guidance on cavity fire barriers
The Masonry Association of Great Britain (MAGB) has launched a new Technical Committee and published its first Technical Note on cavity fire barrier installation.
MAGB announced the cross-sector group alongside Technical Note TN-01/26, which addresses cavity fire barriers and raises concerns about increasing use of zero-compression products.
MAGB said the Committee brings together senior technical specialists from across the masonry supply chain, including brick and component manufacturers, fire barrier and insulation suppliers, façade contractors, structural engineers, warranty providers and training bodies.
TN-01/26 marks the first step in a programme intended to raise awareness of long-term fire safety performance within masonry construction.
What TN-01/26 sets out on compression
In Technical Note TN-01/26, MAGB states that zero-compression cavity barriers may achieve compliance in laboratory fire testing, and that buildings change over time.
The guidance outlines structural frame shortening caused by creep and shrinkage, brickwork settlement, mortar movement, thermal expansion and construction tolerances as factors that can increase cavity dimensions.
Barriers installed without positive compression rely on exact geometry at the point of installation.
As movement occurs, gaps of only a few millimetres may allow flame and hot gases to bypass the barrier.
Because these interfaces are concealed once construction is complete, failures are not detectable through routine inspection.
The Note recommends installing horizontal and vertical cavity fire barriers with compression, with a nominal minimum preload of 5mm unless greater compression is justified by manufacturer testing.
Committee remit and next publications
Keith Aldis, chair of the Masonry Association Technical Committee, said: “This Committee has been formed to bring senior technical expertise from across the masonry sector into one forum with a clear purpose – to identify emerging risks and provide practical, evidence-based guidance to the industry.
“Our first Technical Note (TN-01/26) reflects our collective assessment of how buildings behave in reality over time.
“Laboratory fire testing is conducted under controlled conditions, but real structures are subject to settlement, shrinkage and differential movement.
“Positive compression in cavity fire barriers is fundamental to maintaining contact and continuity as that movement occurs.
“Our guidance is intended to support long-term fire integrity and promote durable, movement-tolerant solutions across the sector.
“This publication is the first in a series of Technical Notes intended to support long-term fire integrity and promote movement-tolerant, durable solutions across the sector.”
MAGB confirmed that further Technical Notes and guidance documents will follow as part of its ongoing technical programme.