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Extraction cleaning - ductwork material
The material a kitchen extract duct is made from is not a trivial detail - it affects how durable the ductwork is, how easily it cleans, and how it performs for fire safety, over the whole life of the system. Choosing well means understanding the options and what matters: the material itself, the gauge, and the standard the ductwork should meet.
The short answer
Kitchen extract ductwork should be made of a suitable material to a proper standard, because it handles hot, grease-laden air and must be durable, cleanable and fire-safe over its life. The usual choice is steel - galvanised steel is common and acceptable, while stainless steel is superior for grease resistance, corrosion resistance and cleanability, so is often preferred especially for demanding duties. The gauge (thickness) matters too: the ductwork must be robust enough for the duty and to withstand cleaning. And the whole thing should meet the recognised standard for kitchen ventilation ductwork, which sets out the material, construction, access and fire requirements. Choosing the material well - a suitable grade of steel, adequate gauge, to the standard - gives ductwork that lasts, cleans properly, and is fire-safe.
Material is not a trivial detail
When kitchen extract ductwork is specified, the material it is made from is easy to treat as a minor detail - but it is a significant choice that shapes how the ductwork performs over its entire life. Kitchen extract ductwork does a demanding job: it carries hot, grease-laden air away from the cooking, so it has to withstand heat, resist the grease that passes through and accumulates, and endure regular cleaning - all for years. The material determines how well it stands up to all of this: how durable it is, how easily and thoroughly it can be cleaned, and how it performs for fire safety. So the material choice affects the ductwork's durability, cleanability and safety throughout its life.
This is why choosing the material well matters. A well-chosen material gives ductwork that lasts, cleans properly and is fire-safe; a poorly chosen one can give ductwork that corrodes, is hard to clean, or performs worse for fire. And because the material is fixed once the ductwork is made and installed, it is a choice lived with for the system's life, like the routing. So it is worth understanding the options and considerations when specifying kitchen extract ductwork - the material itself, the gauge, and the standard to meet - to make a choice that serves the system well for its whole life rather than one regretted later. The material is a foundational decision, not a trivial detail.
Galvanised and stainless steel
The usual material for kitchen extract ductwork is steel, and the main choice is between galvanised steel and stainless steel. Galvanised steel - steel coated with zinc to resist corrosion - is common and acceptable for kitchen extract ductwork, and is often used because it is a practical, established choice. It does the job in many kitchens, providing durable ductwork suitable for extract duties. So galvanised steel is a standard, workable option that is widely used and meets the need in many cases.
Stainless steel is the superior material, and is often preferred especially for more demanding duties. It resists corrosion better than galvanised steel, stands up better to the grease and the cleaning, and its smooth, non-corroding surface is easier to clean thoroughly and keeps cleaner - which matters for grease-laden extract ductwork that has to be cleaned regularly. So stainless steel offers better durability, better grease and corrosion resistance, and better cleanability, making it the stronger choice where those qualities are valued or the duty is demanding. The trade-off is typically cost - stainless steel costs more - so the choice between galvanised and stainless is often a balance between the superior performance of stainless and the practical, lower-cost option of galvanised, decided by how demanding the duty is and how much the extra qualities of stainless are worth for the particular kitchen.
Gauge and construction
Beyond the material itself, the gauge - the thickness of the metal - matters, because the ductwork has to be robust enough for its duty and to withstand the demands placed on it. Kitchen extract ductwork needs to be of an adequate gauge to be durable, to handle the conditions of carrying hot grease-laden air, and to withstand the regular cleaning it undergoes - cleaning that can be vigorous, so the ductwork must be substantial enough to take it without damage. Ductwork that is too thin may not stand up to the duty or the cleaning over time, so the gauge has to suit the demands. So specifying an adequate gauge is part of choosing the ductwork well, alongside the material.
The construction more broadly matters too - how the ductwork is made, jointed and assembled, so that it is sound, does not leak, and can be accessed and cleaned. Well-constructed ductwork of a suitable material and adequate gauge is durable, cleanable and reliable; poorly constructed ductwork can leak, be hard to clean, or fail. So the choice is not just the material but the whole specification of the ductwork - the material, the gauge, and the construction - all of which should suit the demanding duty of kitchen extract. Getting these right gives ductwork that stands up to the job for its life; skimping on any of them risks ductwork that does not. This is why the ductwork should be specified properly rather than made from whatever is cheapest, so that it genuinely suits the demanding conditions it will face.
Meeting the standard
All of this - the material, the gauge, the construction, and the access and fire requirements - is drawn together by the recognised standard for kitchen ventilation ductwork, which sets out how kitchen extract ductwork should be specified and made. There is an established specification for kitchen ventilation systems that covers these things, so that ductwork made to it meets the requirements for the demanding duty of kitchen extract - the right material and gauge, proper construction, access designed in for cleaning, and the fire requirements the ductwork must meet, such as being fire-rated where it passes through fire compartments. Meeting this standard is the way to ensure the ductwork is properly specified.
So the practical answer to choosing ductwork material for a kitchen extract is to specify it to the recognised standard, choosing a suitable grade of steel - galvanised as a workable option, stainless where its superior qualities are wanted or the duty demands - of adequate gauge, properly constructed, with access and fire requirements met. This ensures the ductwork suits the hot, grease-laden, regularly-cleaned duty it faces, and lasts, cleans and performs for fire safety over its life. Getting the material choice right, within a proper specification to the standard, is a foundational decision that pays off for the whole life of the system - which is exactly why it is worth understanding and getting right when the ductwork is specified, rather than treating the material as a detail to be decided by cost alone.
The takeaway
The material a kitchen extract duct is made from shapes its durability, cleanability and fire safety over the whole life of the system, so it is a foundational choice, not a trivial detail - the ductwork handles hot, grease-laden air and regular cleaning for years. The usual material is steel: galvanised steel is common and acceptable, while stainless steel is superior for grease and corrosion resistance and cleanability, so is often preferred, especially for demanding duties, at a higher cost. The gauge matters too - the ductwork must be robust enough for the duty and the cleaning - as does sound construction.
All of this is drawn together by the recognised standard for kitchen ventilation ductwork, which sets out the material, gauge, construction, access and fire requirements. So the way to choose well is to specify the ductwork to that standard - a suitable grade of steel, adequate gauge, properly constructed, with access designed in and fire requirements met. This gives ductwork that lasts, cleans properly, and is fire-safe over its life. Getting the material right within a proper specification is a decision that pays off for the system's whole life - worth understanding and getting right when the ductwork is specified.
Questions
Because it shapes the ductwork's durability, cleanability and fire safety over its whole life. Extract ductwork carries hot, grease-laden air and endures regular cleaning for years, so the material determines how well it stands up to the heat, grease and cleaning - making it a foundational choice, not a trivial detail.
Steel - the main choice being between galvanised steel, which is common and acceptable, and stainless steel, which is superior. Galvanised (zinc-coated) steel is a practical, established option; stainless steel resists corrosion and grease better and cleans more easily, so is often preferred for demanding duties, at a higher cost.
It depends on the duty. Stainless steel offers better durability, grease and corrosion resistance, and cleanability - a real advantage for grease-laden extract ductwork cleaned regularly - but costs more. The choice is a balance between its superior performance and the lower-cost, workable option of galvanised, decided by how demanding the duty is.
Because the ductwork must be robust enough for its duty and to withstand the regular, sometimes vigorous cleaning it undergoes. Ductwork too thin may not stand up to carrying hot grease-laden air or to cleaning over time, so an adequate gauge is part of choosing the ductwork well, alongside the material and sound construction.
Yes - a recognised specification for kitchen ventilation systems that sets out the material, gauge, construction, access and fire requirements. Ductwork made to it meets the requirements for the demanding extract duty, including being fire-rated where it passes through fire compartments and having access designed in for cleaning.
Specify it to the recognised standard: a suitable grade of steel - galvanised as a workable option, stainless where its qualities are wanted or the duty demands - of adequate gauge, properly constructed, with access and fire requirements met. This ensures the ductwork suits the hot, grease-laden, regularly-cleaned duty and lasts over its life.
Well-specified ductwork of a suitable material, with access designed in, cleans properly - and our cleaning keeps whatever ductwork you have clear of the grease it accumulates, to the proper standard.
