Phoenix Journal · Ductwork
Every commercial kitchen extraction system needs two very different document sets, and confusing them leaves you exposed. Here is what the design pack and the as-built record each prove.
Ventilation paperwork
A commercial kitchen extraction system is only as trustworthy as the documents that describe it - and there are two very different sets of paperwork that people routinely muddle together.
When a landlord, an insurer or an environmental health officer asks to "see the documents for the ventilation system", they rarely mean one thing. There is the paperwork that says what the system was meant to be - the design intent, the calculations, the drawings issued before a single duct went up. And there is the paperwork that says what the system actually became, and how you are meant to run and clean it - the as-built record and the operation & maintenance manual. Both matter, and a system with only one of them is a system you cannot fully defend.
The two get confused because they overlap and because a good installer hands them over together. But they answer different questions, they are produced at different stages, and they fail you in different ways when they are missing. Below we set the design pack against the as-built and operational record so you can see what each one buys you, and what you are exposed to without it. Everything here sits within the recognised UK framework: BESA's DW/172 for kitchen ventilation, DW/144 for the ductwork itself, TR19 Grease for hygiene and access, and the CIBSE and BSRIA guidance that governs commissioning and handover.
The design pack is the set of documents produced before installation. It captures the reasoning behind the system: how big the canopy needs to be, how much air it must move, how the duct is routed and sized, and how the whole thing keeps people safe. In a properly run project this pack is built around BESA's DW/172, the specification for kitchen ventilation systems, with the ductwork itself detailed to DW/144.
A design pack worth the name will include the design specification and load calculations - extract volumes, air change rates, duct velocity and static pressure across the fan - along with schematic and layout drawings, the equipment schedule (canopies, filters, fans, attenuators selected against the EN 16282 series), the filtration strategy, and the gas safety design. That last point is not optional: a kitchen with gas appliances needs an interlock so the gas supply cannot run without proven extraction, designed in line with BS 6173. Crucially, a competent design also plans for cleaning access from the outset, positioning inspection panels so that TR19 Grease cleaning can reach the whole internal run rather than leaving buried, ungetatable sections.
Pros
Cons
The as-built record and the operation & maintenance manual are produced at the other end of the job, at handover. Where the design pack says what should be built, these say what was built and how to keep it working. The as-built drawings redline the design to reflect the real installed routes, damper positions and access panels. The O&M manual then wraps that up with commissioning results, manufacturers' data, and the maintenance regime.
A complete handover set includes the marked-up as-built drawings, commissioning certificates recording the measured air volumes at every terminal - regulated in line with CIBSE Commissioning Code A and BSRIA BG 49 - and the gas interlock proving test. It carries the manufacturers' literature for each item of plant, the recommended service intervals, and the cleaning schedule. For commercial buildings this feeds a building logbook to CIBSE TM31, which is a statutory expectation under Part L of the Building Regulations for new and substantially refurbished services. Best practice for assembling the manual itself follows BSRIA's BG 01 handover guidance and CIBSE Guide M for the maintenance strategy. Because seasonal commissioning readings take time, a compliant final manual is often only fully closed out some months after the kitchen opens.
Pros
Cons
This is not really a contest with a winner. The design pack protects the reasoning; the as-built and O&M record protects the reality. A system with a beautiful design pack but no honest as-built drawings cannot be cleaned to a standard you can certify. A system with a tidy O&M manual but no design rationale leaves you exposed the moment you want to change the menu, extend the kitchen or defend a noise or odour complaint. If you inherit a kitchen with neither, treat that as a live risk and rebuild the record: a survey can reconstruct as-built drawings and re-establish access, which is the minimum you need before any credible cleaning regime.
Keep the two sets together, keep them current, and make sure the as-built version genuinely reflects site reality rather than an untouched design print. When those documents are honest, everything downstream - servicing, insurance, gas safety and grease cleaning - gets easier to prove.
Questions
Design drawings show what the system was meant to be - the intended duct routes, sizes and equipment worked out before installation, usually to BESA's DW/172. As-built drawings are marked up at handover to show what was actually installed, including the real access panel and damper positions. The as-built set is the one your cleaning contractor relies on, because you cannot certify a TR19 Grease clean of a run you cannot locate or reach.
There is no single law that lists every document, but several requirements bite together. A building logbook to CIBSE TM31 is a statutory expectation under Part L of the Building Regulations for new and refurbished services, gas interlock design and proving are required under BS 6173, and TR19 Grease records are what insurers and environmental health officers expect to see. In practice, missing paperwork tends to surface as a failed inspection, a rejected insurance claim or a compliance notice.
Commission a survey to establish what is actually installed and to rebuild an as-built record, including where cleaning access exists and where it is missing. That gives you a baseline to arrange TR19 Grease cleaning against and to plan any access improvements. You can reconstruct the design rationale later, but the as-built picture and safe cleaning access are the immediate priority before you rely on the system.
Phoenix Duct Clean · by the numbers
Phoenix surveys and cleans kitchen and building ductwork to the TR19 standard - measured, cleaned and certificated, UK-wide.