What is it that contractors are giving away by not doing the work right the first time? Is it a floor, an HVAC system or even a whole building? Studies and logic prove that doing something right the first time is always less expensive than doing it a second or third time. The problem many managers have with a companywide campaign focusing on doing things right the first time is they see it only as a motivational program. They feel they must persuade, inspire, encourage or even demand the workers to do it right. The truth is that to achieve quality right the first time it takes a system. One must set the standard or expectation and then insert preventions and checks to ensure it happens.


The only real standard of quality is zero defects — work done right the first time — no errors. If one does not set that standard, no one will reach it or for it. Some argue that zero defects are impossible and settle for a lesser target such as “Six Sigma,” which means only 3.2 defects per million opportunities.

But that is like saying, “We do not want too many accidents; just a few.” How many accidents are implied in a company’s safety target if not zero? Talking about defects or accidents is the same thing. How many do you want to have? Zero is the only acceptable target.

Is it possible?  It can be done. You must expect it to achieve it. If one sets a zero-error target and invests much time and energy in exhorting the workers to not make errors, no errors might happen once in a while, but not consistently. The secret is knowing that defects are preventable. Zero errors may happen by luck occasionally, but to consistently achieve it requires prevention systems.

W. Edwards Deming, a world-famous quality expert, taught that only about 6 percent of all defects are errors made by the workers. The rest came from poor or nonexistent management policies and practices.

How do you achieve zero errors or defects? Learn the root causes for the defect and implement countermeasures. It does take effort to analyze and identify root causes. Nothing worthwhile is ever gained by default. The challenge is not if it can happen, but getting managers and workers to think zero defects is possible.


One way to prevent errors is mistake-proofing. This system uses process or design features to prevent errors or the negative impact of those errors. Mistake-proofing is also known as “poka-yoke” (pronounced poka-yokay), Japanese slang for “avoiding inadvertent errors.”

The elevator brake is an early example of mistake-proofing. This braking system enabled skyscrapers to be built. Before there were reliable elevator brakes, buildings would only be built up to five stories. This was because the elevator systems were not trustworthy and only used to haul material. People would climb the stairs but would typically not go up more than five stories. Elisha Otis did not invent the elevator, but he put the brakes on it — arguably more important.

The Otis-designed elevator brake was first showcased at the New York exposition in 1853. Otis rode an elevator above the crowd and had an assistant cut the cable. The elevator brake stopped the elevator — and Otis from falling — and the world of constructing tall buildings was forever changed.

Shigeo Shingo, an early “lean” manufacturing champion in Japan, is the father of poka-yoke. He felt that there are various levels of applying mistake-proofing. The first level is to design changes into the processes to prevent errors.

In construction, the industry eliminates installation errors by designing parts to only be put in one way.

If you can’t design ways to prevent errors into the physical product, you can try to simplify the process and eliminate steps so errors associated with that step don’t occur. Mistake-proofing requires a sound understanding of what happens in the process and why.

Just don’t

The Japanese say, “Don’t get it, don’t make it, don’t send it” regarding defects. This requires learning to follow this slogan. To never accept a defective part, report or material means one needs to know what a “defect” is for the work being done. Never make anything that is defective. Not that workers try to make defects, but for this to work there needs to be methods and aids to help workers know when they are installing it right.

To never pass on a known defect, workers need to know when the work is done right and need immediate feedback when something is passed on that is defective.

It is common to hear complaints from the field crews that the fabrication shop is sending out defective material. Shop supervisors say they do not hear about the defects from the field. Ask the field workers why they don’t report defective material and they say they don’t want to upset the relationship they have with the shop. So the field workers do their own workarounds and the problem is never addressed. The field is trying to do what they feel is best, but in reality they are compounding the problem by not reporting it to the shop.

In construction, owners typically allow each worker to customize how he or she does things. Inconsistent processes are more difficult to mistake-proof because there are fewer predictable elements that can be used to check the process. Creating consistent processes will aid achieving built-in quality.

The next level

The next level of mistaking-proofing is to inspect the source or cause of errors and put in place countermeasures so the error can’t happen. One HVAC installer has the foreman mark each end of the duct with a grease pen. The end is marked “A” and the next piece’s end is also marked “A.” This signifies that the two pieces are to be connected together. While the drawings and the labels on each piece of duct tell the correct installation, the highly visible markings ensure correct installation. A concrete contractor marks the molds with different colors corresponding to the strength of the mix to avoid incorrect pours.

If you can’t design to prevent mistakes, the next level of mistake-proofing is to detect the error as rapidly as possible to avoid any, or to keep to a minimum the harm the error may cause. Try to do this as early as possible, while a fix is still relatively easy. Testing a valve for leakage when it is being fabricated and connected in modules while in the shop is better than if undiscovered until after all is installed.

If the mistake itself cannot be prevented or effectively detected, then the last level of mistake-proofing is to try to prevent the impact of the mistake. Some contractors will test their piping systems in sections before testing the entire system. This helps minimize the impact of defect pipes or values.

Humans make errors and with mistake-proofing systems, these errors can be eliminated or reduced. Shingo called his approach error-proofing. When people incorrectly called it “fool-proofing” in English, he corrected them by saying we call people “fools” but this is about helping people not make errors, not about calling them fools.

To error is human; to not put in place systems to prevent possible errors might still be called foolishness.