A growing number of construction firms are embracing the Lean methodology that emphasizes maximizing value for the customer while minimizing waste. The approach is simple and attractive in an industry where budgets, timeframes, and safety are all critical, but the project delivery is very different than traditional construction methods. This makes proper execution of the philosophy and techniques difficult to implement.
Lean construction borrows from the manufacturing approach developed by Toyota after World War II. Of course, it is much easier to produce repeatable, forecastable results in the controlled environment of a factory floor than in the more unpredictable world of construction. Greater variation and workflow disruptions are to be expected.
It is also important to note that there is no one cookie-cutter approach to Lean construction. There are a number of tools, including the Last Planner System, Integrated Project Delivery, Building Information Modeling, 5s, and Kaizen Events, that can be used in combination to achieve Lean. This gives practitioners a wide range of options that can be applied to each project.
There are, however, guiding principles that help firms achieve lower costs, reduced construction times, more productivity, and efficient project management. They represent a holistic approach to the construction process.
Identify Value from the Customer’s Point of View
The traditional approach to construction focuses on what the customer wants you to build – what’s included in the plans and specifications. Lean construction, on the other hand, recognizes that the customer's values are deeper than that. It isn’t just about what to build, but why. Truly understanding value from the customer’s point of view requires a different level of trust established very early in the planning phases of a project.
Lean construction brings together all stakeholders, including the owner, architect, engineers, general contractor, subcontractors, and suppliers. The project team not only delivers what the client wants, but they provide advice and help shape expectations throughout the project.
Define the Value Stream
Once you have a clear understanding of value from the customer’s point of view, you can lay out all of the processes necessary to deliver that value. This is called the value stream. For each activity, the necessary labor, information, equipment, and materials are defined. Any steps or resources that don’t add value are removed.
A primary goal of Lean construction is eliminating or minimizing waste at every opportunity. Lean construction targets eight major types of waste:
Defects: Defects are anything that is not done correctly the first time, resulting in rework that wastes time and materials.
Overproduction: In construction, overproduction happens when a task is completed earlier than scheduled or before the next task in the process can be started.
Waiting: The most common scenario that leads to waiting in construction is when workers are ready, but the necessary materials needed for the work to be completed have not been delivered, or the prerequisite prior task has not been completed.
Not Utilizing Talent: Workers on a construction project have a range of skills and experience. When the right person is not matched to the right job, their talent, skills, and knowledge go to waste.
Transport: The waste of transport happens when materials, equipment, or workers are moved to a job site before they are needed. It can also refer to the unnecessary transmission of information.
Inventory: Materials that are not immediately needed are considered excess inventory. They tie up
Motion: Movement that is not necessary, like
Flow of Work Processes
The ideal state of a Lean construction project is a continuous, uninterrupted workflow that is reliable and predictable. The sequence is key in construction; you can’t start building the frame until the footings are set, for example. Clear communication between all parties is essential to achieving flow. When one part of the project gets behind or ahead of schedule, it is essential to let everyone know so that adjustments can be made to avoid the wastes of waiting, motion, and excess inventory.
Pull Planning and Scheduling
Creating reliable workflows depends on work being released based on downstream demand. Lean construction recognizes that this is best done by those performing the work, often subcontractors. Participants communicate and collaborate closely with each other to determine the schedule of tasks.
The belief that it is possible and necessary to continuously improve processes and eliminate waste is the heart of the Lean philosophy. Opportunities for improvement are identified and acted upon during the project and applied to future projects.
The construction industry is not immune to the tendency to stick to old ways and resist change, but the many benefits of the Lean approach are compelling more and more firms to take on the challenge. When projects come in on time, on