Page 7 - MCRMA Metal Matters Oct 2022

Cavity Barriers and Fire Stopping Explore the

by Chris Hall, external affairs director, Siderise Insulation Limited Knowledge Base

Most modern buildings contain a multitude of By their function, ventilated rainscreen systems Horizontal open state cavity barriers
concealed cavities and voids within or passing create a concealed space (cavity) that can, in the are delivered to site pre-cut to
through walls, floors, ceilings and roofs. event of a fire, provide a route for the passage for size to suit the width of the cavity
Effective fire stopping and cavity barriers are flames, hot gases, and smoke to move, unseen, less the air gap size. They have an MCRMA has produced four CPDs based on its
essential elements of fire protection to restrict between separate compartments of a building. intumescent front face which allows guidance document GD39 Sustainability and durability
the spread of smoke or flames, and to maintain The accepted method of inhibiting the fire spread an air gap to be maintained (when in of metal roofing and cladding systems.
compartmentation. the open state) to facilitate airflow for
within such a concealed cavity is the use of cavity
The Metal Cladding and Roofing Manufacturers barriers. These will be positioned on the line of ventilation. ▶ The introduction and overview CPD looks at how
metal roofing and cladding systems and their
Association (MCRMA) has published a guidance any compartment wall or floor so that they sub- Open state cavity barriers are associated components can significantly contribute
document, supported by an online CPD module, divide the building both horizontally and vertically supplied with a continuously factory to achieving a sustainable building envelope
titled GD36 Cavity barriers for ventilated rainscreen into specific compartments in line with Building bonded reactive intumescent strip solution to meet both current and future needs and
facades which considers the key questions Regulations, the fire strategy plan for the building, on the leading edge and will normally requirements. and systems.
about cavity barriers and offers guidance for their or specific requirements of warranty providers come with a weather resistant
correct specification. The document explains the or insurers. Cavity barriers will also close off coating. An intumescent strip is a ▶ Durability of metal roofing and cladding systems
difference between a fire stop and a cavity barrier; penetrations through the façade such as windows, material that is designed to activate - the aim of current UK government policy is to
the types of cavity barriers used in ventilated doors, and openings. at a critical temperature and expand achieve net zero by 2050 and one way that can
rainscreen facades and examines the regulations It must be noted that the minimum requirements to close off the purposely designed assist in this is through having buildings built
that apply to the different countries of the for the for the performance of cavity barriers can vary air gap to slow the fire propagating for durability with long design lives and utilising
various parts of the UK. for a specified length of time, materials, products and systems to construct them
depending on which part of the UK they are
The role of fire stops and cavity barriers in building being used. In addition to the guidance set out by normally 30, 60, 90, or 120 minutes, that can match the desired design life. This CPD
examines how Life Cycle Costing can be used to
depending on the specified product’s
construction is often confused. For fire stopping, the various country-specific technical guidance integrity and insulation performance. consider all relevant costs to ensure value for money
Approved Document B defines a fire stop as “a seal documents, warranty providers will have additional over the life of a building.
provided to close an imperfection of fit or design requirements regarding the performance and MCRMA member companies provide
tolerance between elements or components, to placement of the cavity barriers. However, it is a wide range of building envelope ▶ Metals: steel and aluminium. This CPD looks in
restrict the spread of fire and smoke.” accepted that fire stopping products should meet solutions for metal-based roofing and detail at the two most common metals used for
the same requirements of resistance as the adjacent cladding products and services, and manufacturing profiled roofing and cladding sheets
Fire stopping needs to attain the same fire and how they and their associated components can
resistance performance as the structural compartment elements, wherever practicable. they can advise on the suitability and significantly contribute to achieving a sustainable
elements and seal the junction of compartment There are two types of cavity barriers which are performance of materials, systems, building envelope solution to meet both current
walls and floors to maintain the integrity of the typically used in ventilated rainscreen facades: and assemblies. and future needs and requirements, thanks to their
compartment. Fire stopping also seals around vertical closed state cavity barriers and horizontal Both the CPD and guidance low maintenance, durability, high recycled content,
penetrations and services and is fundamental to open state cavity barriers. document are available at recyclability and energy efficiency.
compartmentation. www.mcrma.co.uk
Vertical closed state cavity barriers are cavity
Cavity barriers are defined in Approved Document barriers that fully fill the void from the outer ▶ Components. This CPD looks at the total
sustainable building design solutions which are
B as “a construction within a concealed cavity surface of the inner leaf to the inner surface of available thanks to a range of complementary
other than a smoke curtain, to perform either the outer leaf. They are typically used to provide components and systems including sustainable
of the following functions: to close a cavity to vertical compartmentation of the external facade high performance thermal and acoustic insulation
stop smoke or flame entering or to restrict the cavity in a ventilated rainscreen and are installed Image showing the horizontal open state products; high durability fixings, fillers, sealants
cavity barrier installed tight to the backing
movement of smoke or flame within a cavity. prior to the installation of a horizontal open state wall prior to the thermal insulation with the and membranes; daylight options, flexible solar PV
cavity barrier. horizontal open state set back to allow for
ventilation of the cavity. options and fastening systems; and ‘green’ and
‘brown’ roof options.
Image showing Image showing
closed state the vertical The modules represent
vertical cavity closed state an anticipated 60 - 120
barriers on cavity barrier
the jamb of an extending to minutes of professional
opening and the full width of development, and
horizontal open the cavity with following successful
state on the the horizontal
head and cill. open state set completion of the CPD,
back to allow a certificate is available
for ventilation for immediate download.
of the cavity.
All modules have been
accredited by the CPD
Certification Service.

More information about the online CPD courses is
available at www.mcrma.co.uk/online-cpds/

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