Lean Construction

Lean construction refers to a construction management approach to project delivery that focuses on maximizing value to customers’ needs and eliminating waste while simultaneously establishing a culture of continuous process improvement among employees. Lean construction aims to increase efficiency by eliminating activities that consume resources but create no value to the home. This approach is relatively new to the homebuilding industry; however, recent practices have shown striking improvement in productivity, quality, safety, resource usage, and other areas with a positive effect on the bottom line for homebuilders. Applying lean construction to homebuilding means getting the right resources to the right place at the right time in the right quantity while minimizing waste (e.g., labor, material, and equipment) and empowering employees to proactively improve their working environment.

Lean construction is the application of the principles of lean production to the construction industry. Lean production has its origins in the automobile [Page 418]manufacturing industry with the Toyota Production System (TPS), which after years of development and implementations, has shown significant savings of labor hours per vehicle and improvement on the vehicle's final quality.

Lean production principles were first tailored to the construction industry by emphasizing production process flow and the conversion of inputs into finished products. The homebuilding industry is characterized by waste, both operational and material; this waste is one of the drivers behind the lean construction movement. As it applies to homebuilding, the main goal of lean construction is to satisfy the homebuyers’ needs by delivering the highest quality home at the lowest cost in the shortest time. The application of lean construction in homebuilding involves three key elements: the application of lean principles, the identification and elimination of the seven types of waste, and the implementation of lean initiatives.

The first element involves the application of the five fundamental principles:

• 1.
  Identify what the homebuyer values—that is, the value as perceived by the homebuyer
• 2.
  Identify the value stream, scrutinize all steps, and challenge any waste (value stream refers to the mapping of materials and information through the homebuilding process)
• 3.
  Build or prep assemblies when crew members need them and keep the materials flowing continuously through the value stream, striving for perfect coordination among trades and subcontractors to ensure smooth transition and eliminate the risk of idle times
• 4.
  Introduce pull between all steps where continuous flow is impossible
• 5.
  Manage toward performance excellence—high-quality construction processes designed for immediate detection of problems

The second element involves the continuous elimination of any one of the seven types of waste identified by lean theory:

• 1.
  Defects: any activity involving rework (e.g., wrong installation, defects in fabrication, and errors in punch lists)
• 2.
  Overproduction: any activity used to build too much or ahead of schedule (e.g., stockpiles of wood frame for windows at the job site too early in the construction process)
• 3.
  Excessive transportation: any activity related to material movement that does not directly support value-added activities (e.g., double handling drywall stacks around the job site)
• 4.
  Idle time: any waiting time (e.g., when a crew waits for instructions or materials at the job site)
• 5.
  Overprocessing: any activity or effort that adds no value to the house (e.g., requiring additional signatures on requisitions, or multiple handling of timesheets)
• 6.
  Excess inventory: any supply in excess of construction process requirements necessary to build the house just in time (e.g., uncut material, work in process, and finished assemblies pile up in the construction site)
• 7.
  Excessive motion: any movement of a crew that does not contribute added value to the house (e.g., when material is stored far away from the point of use or when workers look for tools)

The third element involves the implementation of the lean initiative through Kaizen events. These are a team-based, intensive, and focused approaches to process improvement that involve employees from different levels (i.e., homebuilders, supervisors, crew members, suppliers) to continuously improve the process and instill a lean culture in the company through the use of lean principles and tools. Kaizen events benefit homebuilders by reducing overhead cost, improving levels of construction quality, and reducing construction time through the elimination of wastes while workers benefit by being empowered with the responsibility, time, and tools to uncover areas for improvement with management's support. A traditional Kaizen event entails seven

...