Long-Lead Item
A material or piece of equipment, such as switchgear, elevators, custom windows, or specialty mechanical units, whose manufacturing and delivery time is long enough that it has to be ordered early, often before other design or construction details are finalized, or it will delay the whole project.
Why it matters
A project schedule built without accounting for a 40-week equipment lead time is a schedule built on a false assumption. Identifying long-lead items early, and ordering them before they'd normally be needed, is often the difference between hitting a completion date and missing it by months.
On a real project
A hospital project's medical gas system requires custom equipment with a 30-week lead time. The project team places the order during design development, months before the mechanical room is even framed, so the equipment arrives right when the space is ready for it instead of holding up the schedule.
Who this matters most to
A Scheduler builds long-lead items into the schedule as their own tracked activities, often starting before construction itself does. A Project Manager pushes to get long-lead items ordered during buyout, sometimes before the full subcontract is even finalized, specifically to protect the schedule.
Where this goes wrong
A project team waits until a mechanical subcontractor is fully under contract to order a custom air handling unit, not realizing it carries a 24-week lead time. The unit arrives four months late, and by then the mechanical room built to receive it has been finished and closed up around empty space, delaying the entire building's opening.
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