Lean construction is a concept from the past that has seen a rebirth in the construction industry. The principles behind lean construction were born in manufacturing during World War II. It is only in recent years that residential and commercial construction has realized the benefits of this type of mindset in this industry.Every year project owners are demanding better product in shorter timeframes. Traditional construction methods meant that the designer was in charge, told the builder what to build, and walked away from the project. Today, project teams are realizing that everyone can get more bang for their buck when they work together from the beginning. Lean construction advocates for this type of teamwork, allowing all team members to cut costs, reduce the project schedule, and increase productivity.
Lean construction principles
Lean manufacturing principles don’t translate directly into construction, where every project is different and there are so many environmental factors that come into play. Even with this challenge, though, many companies have been successful incorporating some of the lean principles into the chaotic construction industry. Some of the principles that have worked well include identifying the owner’s values, eliminating waste, continuous planning, and improved communication.One of the first steps in a project is the meeting between the design team and the owner to talk about the owner’s vision for the project. In lean construction, this meeting will often include the general contractor, construction manager, and key subcontractors as well. Everyone participates in the process of discovering what the owner needs, wants, and desires, and what is most important about the project.
With these values or goals in mind, the team then proceeds with the project design. Many meetings may occur, with team members brainstorming ideas or asking questions of other members. The collaborative effort helps to ensure that details aren’t missed, the design intent is understood by everyone, and everyone knows what is important to the owner.
Waste hurts all members of the project team. It results in lower revenues, longer production times, and lower quality projects. The project team works collaboratively to eliminate as much waste as possible on the job. Waste can take on many forms, such as overproduction, unused inventory, construction defects, and the underutilizing and misusing of labor. Any activities that don’t directly serve the owner’s values are also seen as waste and are eliminated as much as possible.
Planning is one of the primary tenets of lean construction. Part of the planning that takes place on a project includes material planning. In lean construction, materials are often scheduled to arrive on site as soon as they are needed, so there isn’t a need to stockpile large amounts of materials. This cuts down on site logistics issues and makes the job safer because materials aren’t being moved around as much.
Like the project team meeting at the beginning of the design, the construction manager or general contractor will conduct a construction kick-off meeting with all the subcontractors and suppliers to determine the project schedule. Instead of building the schedule linearly, from start to finish, team members are encouraged to think out of the box and figure out how they can do their work more efficiently and quickly. The GC compiles the schedule with the production milestones and task durations as suggested by the subs. The whole team buys into the schedule and continues to work on it as the project goes along.
Communication can be very difficult on large projects, which makes the use of technology and other forms of communication more important. The streams of communication run from the owner, to the GC, then to the subs, but also the other way. Team members have regular opportunities to collaboratively work together on problems and issues as they come up.
Lean construction strategies
How are these principles enacted on the job site? There are strategies that help the team achieve their goals for collaboration and efficiency.Pull planning or the last planner system is a way of putting together the job schedule that allows input from all team members. It is based on five key processes:
- Collaborative programming – All project team members create and agree on the sequencing and compressing, if needed, of the schedule.
- Make ready – All members help to ensure that tasks are complete before the next tasks are started. There is a shorter look ahead period that allows each team member to know what they are responsible for completing in the next day or week.
- Production planning – The team collaborates on what tasks need to be completed each day or week.
- Production management – Everyone monitors progress on the tasks, to ensure that the project remains on schedule.
- Continual improvement – The team learns and improves as the project goes along. Processes are revised as needed so the work can proceed smoothly.
The use of building information modeling (BIM) software is also key to the lean construction process. This software allows the project team to look for problem areas and inconsistencies in the design before construction begins. The software models all aspects of the constructed building as a three-dimensional model. It can analyze the design for utility conflicts and other potential problems and can allow the design team to see changes made in real time.
BIM essentially allows the team to build the building before a shovel hits the dirt. When problems are identified, they can easily be corrected in the virtual world, saving money in the real world. The software can also give owners preliminary information on energy use and occupancy factors, so design revisions can be made earlier in the design process, saving the owner money in the long run.
Some projects take advantage of the benefits of prefabricated or modular construction to help expedite their schedules and reduce waste. This type of construction can significantly reduce the project schedule, as multiple scopes of work can be working at the same time when some of them are located off-site. For example, site work can begin as walls are being built in a warehouse nearby. Those walls are then assembled on site within days of delivery, significantly speeding up the drying-in process and the overall project schedule.
Project planning includes predicting when materials will be needed on site and setting up delivery so it coincides with installation. These just-in-time deliveries reduce the storage space needed on site, prevent materials from getting dirty or damaged while waiting to be installed, and allow installation contractors to be more efficient with their work.
Benefits of lean construction for owners
There are many benefits that owners can expect from employing lean construction on their projects. Some of the most noteworthy are the achievement of the owner’s values, improved quality, reduced costs, and shortened schedules.Projects that begin by defining the owner’s values and ensuring that all team members are aware of them and working towards them have a greater chance of meeting those values. The team works together to self-correct and ensure that when an issue comes up, the owner’s values are always considered first.
The project team works together to make the owner’s vision and values a reality during the project. By collaboratively working together, they can ensure that the work is of a higher quality and that defects and other waste are eliminated.
By using BIM software and bringing the construction team together earlier in the process, projects using lean construction strategies can reduce overall building costs. Though there may be additional costs incurred for modeling and additional meetings, savings will be gained by cutting down on wasted work, defects, last-minute design changes, and construction delays.
Through pull planning, just-in-time deliveries, and thorough task planning and scheduling, the project team can often significantly shorten the construction schedule. When team members are working collaboratively from the beginning, they often find new ways to work together to expedite production.
