Breaking Down the Principles of Lean Construction
The implementation of lean construction has been gaining traction over the last several years as more and more firms realize the benefits of applying lean thinking to construction. The concept is simple enough, maximize value for the client while at the same time minimizing waste. Proper execution of the lean construction philosophy, on the other hand, can be difficult to implement. For starters, lean construction involves a completely different approach to project delivery from traditional construction methods.
Lean construction is based on the lean manufacturing popularized by the Toyota Production System developed by Taiichi Ohno after World War II. One of the difficulties in applying lean thinking to construction is that unlike manufacturing, construction doesn’t always take place in a controlled environment, which can lead to greater variations making predictable and reliable workflows difficult to achieve.
One of the other hurdles to lean construction is that there isn’t one set method or process to achieve lean. There are a number of tools, methods, and systems that have been developed in an attempt to translate lean thinking to construction. Many of these can be used independently or jointly to implement lean practice in construction projects. You’ve got everything from the Last Planner System, Building Information Modeling, Integrated Project Delivery, Kaizen Events and the 5s process. These are just a few of the tools and systems used in applying lean principles to construction.
Cutting costs, reducing construction times, increasing productivity and efficiently and effectively managing projects can all be achieved through successful implementation of lean principles. These principles should drive and guide you to discovering and developing the tools and methods to achieving the goals of lean construction and taking a more holistic approach to project delivery.
Identify Value from the Client’s Point of View
What your client truly values in a construction project typically goes beyond delivering what’s laid out in the plans and specs. It’s more than just the quality of your work or completing a project on time and within budget. This requires a customer-focused approach that can best be achieved by building a relationship with the client. In lean construction, this should include all stakeholders: owner, architect, engineers, general contractor, subcontractors, and suppliers.
Identifying client values should begin early in the conceptual planning phase of a project and be carried on through construction. It’s about understanding not only what your client wants, but why they want it so the project team can manage expectations and best advise the client. A deep level of trust must be established between all stakeholders in order to successfully implement lean practices.
Identify Processes that Deliver the Value Stream
The value stream is simply what the client values. Once you’ve identified value from your client’s perspective, it’s time to identify the processes needed to deliver the value stream. All steps in the process should be carefully mapped out to determine what activities are involved. Take into account labor, information, materials, and equipment needed for each activity. Any steps in a process that don’t add value for you client should be eliminated.
Lean construction is accomplished by cutting out waste. The eight major types of waste in construction are easy to remember because they result in DOWNTIME.
This is anything not done correctly the first time which results in rework. This wastes time in having to make the repairs and materials needed to correct the work.
In construction, this type of waste occurs when a task is completed faster than scheduled or before the next task in the sequence is ready to start.
This wasted time where workers are stuck waiting for materials to be delivered or for preceding work to be completed. This disrupts the workflow and results in workers waiting for work.
Not Utilizing Talent
You wouldn’t hire an electrician to fill a construction laborer position. It would be a complete waste of their talents, skills, and knowledge.
This can be the transportation of equipment, materials, and workers to a jobsite before they are needed or it can refer to the transmission of information with no added value.
In lean construction, you want to move toward “just in time” inventory as opposed to “just in case” inventory.
This is any unnecessary movement that can be eliminated, such as having to make multiple trips across the jobsite to get more tools or materials.
Excess processing is typically generated when having to deal with too many instances of other waste such as defects or inventory. Double-checking or adding extra processes to try and eliminate other areas of waste will involuntarily lead to more waste from over processing.
Achieving Flow of Work Processes
The goal in lean construction is to achieve a continuous workflow that is reliable and predictable. Each stage of production is done in sequence. For example, you wouldn’t start hanging drywall in a room until all of the electrical and plumbing was roughed in. In order achieve flow all parties have to communicate and work together to avoid interruptions. You want to avoid workers waiting for work or vice versa. Dividing a project up into separate production zones can help contractors ensure they have the capacity to finish each task on schedule. If one stage of production gets behind or ahead of schedule, it’s important to communicate and make adjustments to avoid the workers waiting for work scenario.
Using Pull Planning and Scheduling
When using pull planning or scheduling the work is released based on downstream demand in order to create reliable workflows. Because work is done sequentially and the completion of one task releases work on the next task. This requires starting from a specific milestone or target completion date and working backward to schedule work when it can be performed.
In lean construction pull planning is done by those performing the work, typically the subcontractors, through communication and collaboration with each other to dictate the schedule of tasks. This is because they are best suited for determining their capacity for performing a given task. They can work with the next subcontractor, or customer, downstream to coordinate schedules and handoffs.
Perfecting the Processes Through Continuous Improvement
Continually making improvements to further eliminate waste and add value is critical in order to perfect your lean construction processes. Not only should adjustments be made throughout the individual project to identify and reduce waste but taking what you learn from project to project will allow you to continually innovate new ways to add value and eliminate waste.