Short answer: there's no reliable single figure — a duct package on a small retail fit-out and one in a multi-storey office can carry the same linear metreage and still sit weeks apart in duration. If someone gives you a duration before they've seen your drawings and programme, treat it as a placeholder, not a plan.
It's tempting to think of ductwork installation the way you'd think about laying cable tray: so many metres, so many days. The problem is that duct doesn't install at a constant rate — it installs at the rate the slowest constraint around it allows, and that constraint is rarely the ductwork itself.
Why linear metreage doesn't predict duration
Standard gauge rectangular sections in common sizes might be available in days. A run built to a specific pressure or leakage class, or anything needing bespoke transformations around structural steel, can carry a fabrication lead measured in weeks — and that clock starts ticking long before an installer picks up a rivet gun. A programme that only counts install days and ignores fabrication lead is a programme that's already wrong before work starts.
Zone availability is really a question about everyone else's programme. Ductwork typically can't go in until first-fix structure, steelwork and often some containment are in place — so "how long does installation take" quietly depends on how reliably the trades ahead of it hand over their zones.
Access and delivery sequencing set the ceiling on how fast work can go even once the zone is live. A single riser feed, one goods lift shared across four trades, or work above 3.5 metres requiring MEWP movement all cap the realistic daily rate — no amount of extra labour pushes past a cap set by a bottleneck rather than headcount.
Testing and commissioning float gets squeezed more often than anything else on a construction programme. Duct pressure testing, leakage testing where specified, and any TR19 Air-related cleanliness requirements need time built in after installation finishes, not layered on top of a fixed handover date that hasn't moved.
A generic illustrative scenario
Picture a single-floor commercial fit-out: standard rectangular ductwork through a ceiling void, one riser feed, sharing the space with electrical first-fix on a four-week window. Fabrication was ordered against a two-week lead, the zone opens on schedule, and testing has a few days' float built in at the end — so four weeks holds. Now change one variable: the riser feed floods and access shifts to a single point serving two floors. The crew hasn't gotten worse and the duct hasn't gotten longer, but the throughput has halved, and four weeks becomes six unless something else in the sequence moves to absorb it.
Common mistakes
Quoting duration from metreage alone, ignoring fabrication lead time entirely. Assuming the ceiling void will be clear on the date the master programme says it will, rather than checking with the trades actually working it. Leaving no float for testing and commissioning. Treating access constraints as a labour problem and adding installers to a bottleneck that more people can't clear any faster — see our note on ductwork installer crew sizing for the same logic applied to labour.
What Cliventa needs
To give a duration that holds up rather than a guess, Cliventa needs the drawings, the specification (including any pressure, leakage or cleanliness requirements that affect fabrication), the proposed programme and zone-availability dates, and confirmation of access and delivery constraints and which other trades share the install zone.
Building a programme? See our guide to building a realistic ductwork installation programme.