Long lead-time item

On a construction project, the amount of time elapsing between the point when an order is placed for an item and its delivery to site is called the ‘lead time’ (or procurement time).

See lead time for a full definition.

For a ‘long lead time item’, this period is extended. A long lead-time is long enough to potentially adversely affect a project’s outcome or long enough to make specifiers aware that such products and components need to be ordered well in advance if they are to be successfully incorporated into the project’s programme of works.

Long lead times may result from numerous variables, such as:

• The supply factory has a very long order book or is experiencing problems.
• Protracted manufacturing processes.
• Extended supply chains.
• Shipping times.
• National or world shortages.
• Political upheavals in other countries.
• Inclement weather.
• Strikes.
• Complex approvals processes.

It is often the case that long lead-times are identified as a result of problems encountered on a previous project – a contractor for example, may be aware that a particular item is always a problem for whatever reason when it comes to supply.

Construction components that involve long lead-times will often require the approval of production drawings prior to ordering. This can add to the lead time, cause further delay and may even result in the component not being ordered at all. Not having a vital component that will allow a project to continue can be a huge problem for construction.

It is crucial that long lead-time items are identified as early as possible in a project as they may affect the critical path. Where a long lead-time item does appear on the critical path, delays in the delivery of that item may extend the entire project programme. This requires careful management, as several items may need to be delivered in sequence to perform a single task, with delays in any one causing a delay to the entire project.

Long lead-times can be a problem when it comes to materials planning and can involve many weeks and months, especially for products that are sourced abroad. These may involve shipping and transit times that are normally long and are sensitive to economic and political developments. They may also involve a supply chain of multiple companies: for example, the product manufacturer who depends on various suppliers for sub-components that go into the final product assembly.

It is important to notify all the parties on a construction project that a product, item or component has a long lead-time as soon as possible. An experienced contractor may be more able to identify such components and inform other stakeholders at the earliest opportunity, this will allow them to order such products at the optimum time. Managing a procurement schedule properly is essential to the success of maintaining a steady and predictable workflow.

Typical components that can have long lead-times include:

• Bespoke cladding and glazing systems.
• Prefabricated concrete and steel frames.
• Mechanical and electrical equipment such as transformers, low- and high-voltage switchgear, boilers, chillers, lifts and escalators
• Specialist personnel and specialist plant, such as cranes and piling rigs.
• Hand-made items.

These are sometimes placed on order prior to the appointment of contractors so they do not delay the project programme.

Some materials with short lead-times and which can normally be taken directly from a manufacturer’s existing stock include simple, mass produced units such as bricks, tiles, paints and timber. However, during boom times, even these items may be in short supply and require long lead-times.

[edit] Related articles on Designing Buildings Wiki

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• Critical path.
• Delay on construction projects.
• Fast track construction.
• Programme consultant.
• Programme float.
• Project crashing.
• Project programme.
• Lean construction.
• Logic links.
• Off-site materials.
• Scheduling construction activities.
• Short period programme.
• Site storage.
• Vesting certificate.