Phoenix Journal · Fire Safety
A refurbishment is the rare moment when the extract, the suppression and the ductwork are all open and changeable at once. Decisions made in those weeks lock in the fire safety, and the cleanability, of the kitchen for the next decade.
Most fire safety in a working kitchen is retrofit: cleaning what is there, servicing what was installed, working around decisions made long ago. A refurbishment breaks that pattern. For a few weeks the canopy, the ductwork, the suppression and the gas are all open and specifiable at once, and the choices made then decide how safe, and how maintainable, the kitchen will be for years. Spend that window well and fire safety is designed in; waste it and you inherit a system that fights you.
Commercial kitchen ventilation in the UK is designed to the industry benchmark DW/172, the BESA specification for kitchen ventilation systems, which covers airflow, ductwork, grease management and access. It is not statute, but environmental health officers, fire inspectors and insurers use it as the yardstick, and a refurbishment is your chance to build to it properly. Get the extraction rates matched to the appliance heat load, size the ductwork for a sensible velocity, and specify materials, stainless steel in the hot zones, that will last. The refurbishment specification is where a safe, cleanable system is either designed in or quietly designed out.
The four decisions that matter
Four fire-related decisions dominate a kitchen refurbishment. First, make-up air: extraction removes large volumes of air, and if it is not replaced the kitchen goes into negative pressure, which slams doors, starves combustion appliances and pulls the system out of balance. A designed make-up air supply keeps everything stable. Second, fire-rated ductwork: where extract ducts pass through fire compartments, they breach barriers the building relies on, so the ductwork must maintain that fire resistance, typically by fire-rated construction or enclosure meeting the relevant BS 476 performance, so a fire cannot travel the duct into another compartment.
Third, suppression: a refurbishment is the natural point to fit or renew a fire suppression system over the cookline, the control designed to knock down a fat or oil fire at source before it can reach the ductwork. Fourth, gas safety: where the kitchen runs gas appliances, a gas interlock to BS 6173 shuts off the gas supply if the ventilation fails, so appliances cannot run without extraction. Designed together at refurbishment, these four decisions reinforce each other; bolted on afterwards, one at a time, they rarely fit as well or cost as little. Building Regulations Part J, which covers combustion air and flues for gas appliances, is a further reason the gas and ventilation design have to be considered together rather than in isolation.
The decision that pays back longest, though, is the least glamorous: cleanability. DW/172 expects access panels along the duct run so the whole system can be inspected and cleaned, because a duct you cannot reach is a duct that cannot be maintained. Grease that cannot be removed is fire load that cannot be reduced, and a system designed without access condemns its owner to years of partial cleans and rising risk. Building in generous, well-placed access panels at refurbishment is a small cost that protects both safety and insurability for the life of the system.
Designing out the fire risk
The reason cleanability sits at the centre of a fire-safe refurbishment is that grease is the fuel. A system designed so every section can be reached and cleaned keeps the fire load down for its whole life, which is why a refurbishment should be planned with the eventual cleaning regime in mind. The logic of a canopy cleaning fire risk assessment is worth applying at the design stage, not just in service: if you can see how the system will be assessed and cleaned once it is running, you can specify the access, the materials and the layout that make that straightforward rather than impossible.
Getting the layout right
Many fire risks in a finished kitchen trace back to layout decisions taken in the refurbishment: appliances too close to combustibles, extract runs forced into awkward geometry, gas and electrics crammed together. Thinking carefully about how to plan a kitchen layout around extraction and gas is where fire safety and workflow meet, because the same clear, well-zoned layout that makes a kitchen efficient also keeps ignition sources, fuel and escape routes sensibly apart. The refurbishment is the one time you can move a wall or reroute a duct cheaply; after the tiles are on, every fix costs more and compromises more.
Questions
DW/172 is the BESA specification for commercial kitchen ventilation systems, covering the design, installation, testing, commissioning and maintenance of extract systems. It is not law, but it is the recognised UK industry benchmark, and environmental health officers, fire inspectors and insurers commonly use it to judge whether a kitchen ventilation system is fit for purpose.
Extraction removes large volumes of air, and if that air is not replaced the kitchen falls into negative pressure. That can slam doors, make combustion appliances misbehave and pull the extract system out of balance. Designing a make-up air supply into the refurbishment keeps the whole system stable and working as intended.
Where kitchen extract ductwork passes through fire compartments, it must not undermine the building's fire separation, so it is typically fire-rated by construction or enclosure to the relevant performance so a fire cannot travel the duct into another compartment. A refurbishment is the right time to get this designed in, along with access panels for cleaning.
Phoenix Duct Clean · by the numbers
Access panels and fire-rated ductwork specified at refurbishment make TR19 cleaning possible for years. Phoenix cleans and certifies commercial extract systems, UK-wide.