Lean construction is the application of the lean discipline to the world of construction. It is a third area of the application of lean principles, preceded by successful applications in manufacturing and product design. It follows the same approach, i.e. the identification and elimination of wastes in eight areas: Motion, Waiting, Talent, Inventory, Transportation, Defects, Over Production and Over Processing.
Multiple Components to Consider
A basic hollow metal door system is made up of multiple components including a three sided welded frame assembly, a steel or wood door, a lockset, at least (3) hinges and a closer, minimally consisting of 7 components. Frequently other components may be required dependent on the functional requirement of the specific opening, e.g. security or environmental needs.
A medium size construction project could easily consist of hundreds of doors while a large project could contain thousands of doors. When the total doors, frames and hardware configurations are considered, the logistics associated with material planning for even a medium size project quickly becomes complex, and the potential for errors and defects multiplies. It’s been said that doors, frames and hardware represent one of the smallest costs on a large construction project but are typically the number one reason why people don’t get paid on time at the end of the job.
Obstacles to Lean Practices in Construction
In addition to the numerous complexities of the physical component quantities and variations, the design of the door system- and specifically the three-sided welded frame assembly-becomes a major obstacle to achieving the full benefits of lean practices in construction. A review of the typical construction process around hollow metal door systems will help to demonstrate the challenge of streamlining this portion of the project.
WASTES: Motion, Waiting, Talent, Inventory, Defects, Over Production
Once the frames are installed the doors and hardware begin to arrive. As with the frames, the doors and hardware must be received, moved and stored until they are needed. The hardware poses a unique problem; it is expensive material and must be stored in a secured area to prevent loss from theft. Hardware is specific to a particular opening, but openings are rarely ready at exactly the right time, causing hardware to be moved and mixed together in the storage areas, resulting in additional waste.
One of the contradictions of the current construction process of hardware management lies in the fact that the door distributor has already sorted the hardware and matched it to specific doors and openings, but this is all for naught once the materials hit the job site. The design of one component (the welded frame) causes a ripple affect across the entire construction process, including the electrical and drywall work. Once the frames, electrical components and drywall are installed, the doors and hardware are brought to the opening for installation and the door assembly is completed.
As this is now months into the construction cycle, it is not uncommon for a portion of the doors, frames and hardware to have been damaged or lost. Consequently, additional effort is now required on the part of the contractor, the supplying distributors and sub-contractors to correct the problems before the rapidly approaching turn-over date to the owner. And, this is not the end of the process.
An Outdated Process Calls for New System
The current state of affairs for using welded hollow metal door systems in building construction is a process that hasn’t changed in decades. Looking at it from a lean perspective, it’s a “push” as opposed to a “pull” process because each preceding step “pushes” its output to the following step. A lean approach creates a flow where the materials and processes are “pulled” to their respective openings just as the openings are ready for those materials, a just-in-time process.
A value stream analysis of this process identified 150 minutes of Value Added time, 54 days of Non-Value Added time and an estimated Non-Value Added cost of $325.00 per opening. Value Added time is the time utilized to actually install and finish the door system excluding any time associated with the 8 wastes. Non-Value Added time is the time specifically associated with the 8 wastes. The estimated cost was obtained from an internal study done by a general contractor.
Clearly the opportunity for a better solution is evident. The contractors who deal with the problems of the current process want a solution. The distributors and sub-contractors want a solution. Even the owners want a solution as they have no particular desire to hold up payment at the job’s end. A solution is possible. Imagine a system that goes from Distributors to Receiving and follows a lateral line through Staging, Install, Disposal of Packaging, and Cleaning. Recall, earlier it was noted the three-sided welded frame was a major barrier to the implementation of a lean solution. Its design dictates the construction sequence and timing. So, accepting the premise that the welded frame assembly is the process bottle-neck, it becomes obvious a different frame design would facilitate a new solution.
Alternate frame designs already exist, but they have some short comings that not all customers accept, e.g. the design or look vs. the welded frame. Suffice it to say that if the proper frame design can come to market, the simpler process becomes achievable. This process models a sequence where the door systems arrive to the job site preassembled, pre-finished in a just-in-time sequence, are immediately moved to their respective opening and installed in a few minutes using a minimal amount of labor.
In order to accomplish this outcome, the frame and door must be installed after the electrical, drywall work and painting have been completed. They would in fact be installed at the end of the job, after the walls are built, the electrical systems are tied in, the drywall is installed and the painters have “left the building.” The challenge is for the commercial door industry to discover the incremental improvements that will produce the desired results. A value stream analysis of this system indicates only 15 minutes of Value Added time is required to complete the installation. The Non-Value Added time is reduced to 30 minutes and the Non-Value Added cost is reduced to $25.00.
Embracing the Discipline of Lean
Contractors around the world are embracing the discipline of lean to drive out wastes in the construction process and are anxiously awaiting new products and methods to help them achieve continuous improvement. The door component manufacturers have done an admirable job of leaning out their manufacturing operations; they know how to make their products with great efficiency. Now they need to turn to the end user customers and apply these same lean principles to the job site.