Quality Control in Construction

Developed by Thomas Reigstad

Summary

Construction sites has through the years been subjected to injuries, accidents and faults. Budgets and deadlines are not kept, because of inadequate planning, errors, and poorly executed work. To satisfy customers requirements and to emphasise the importance of security, construction firms are now dedicating increasingly amounts of resources to prevent this. Political and private initiatives have made quality control a separate field in construction.

This article will look at how quality control is used, the benefits and values of it and which supporting activities are used. The Quality Control concept is wide and are used in many areas and industries. Thus, the article will mainly focus on the overall basics of the Quality Control and discuss the tools directed at the construction industry. The article will first present some of the very basic concepts before describing some tools commonly used, like, Quality Plans, Cause and Effect Diagrams, Check Sheets and Cost of Quality. Finally the article will discuss the limitations of the Quality Control.

Definition: Quality Control

Quality Control is often associated with Quality Assurance (QA) and Quality Management Systems (QMS). They all correlate and depend on each other all thought there are different definitions. The American Society of Quality have made the following definitions of the terms:

Quality Assurance is: “All the planned and systematic activities implemented within the quality system that can be demonstrated to provide confidence that a product or service will fulfil requirements for quality.”

Quality Control is: “The operational techniques and activities used to fulfill requirements for quality.”

Thus, the difference between them is mainly that the QA is everything involving the QC such as documentation, planning and the supporting activities around QC, while QC is the actual controlling part. Together QA and QC are parts of the QMS. The concept of Total Quality Control (TQC) emphasizes the use of the tree to provide the best possible quality in every part of the company.

Background

Until the mid-20th century the conventional way to make sure products were up to standards was with post-production controls, where the defect products would be repaired or thrown away. After the second world war companies started to rethink the idea as factories and production became more efficient and the demand bigger. Toyota introduced the Toyota Production System which later influenced the Lean-philosophy. In the 50’s the Deming-circle was introduced by W. Edwards Deming and is considered the origin of the total quality management (TQM). In the end of the 60’s the term Quality management systems arises. This was the first time where they would look at the entire process of making a product, not just the production in itself. The management and the service provided to the customers would be taken into account just as the quality of the product. The entire system is built up to provide the best possible quality.

Plan - Do - Check - Act

Figure 1: The PDCA circle

One of the most basic ideas of the QC and especially the TMC is the theory behind Plan - Do - Check - Act (PDCA). It is based on the Deming Circle introduced by W. Edwards Deming in the 1950's. The concept has influenced the construction industry and many others since. PDCA is based on four parts, each shown in figure 1.

- Plan: The first step of the PDCA is the planning part. At this level the company will create an overview of the project and use the information they got in combination with previous experience they have acquired. Planning implementation of new methods and tools is a central part to the PDCA.

- Do: This is the execution of the production or the construction. With on-going supervision of the quality process the results of the planning will be used to provide the best possible quality for the customer. Keep in mind, keeping time limits, costs and safety regulations is just as important as the actual product delivered. At this point it is important for every part project team are aligned and keep improving on every level of the organization.

- Check: Evaluating the initiatives and measures implemented is important to keep improving a business. Do they improve the quality provided and does it justify the cost to accomplish the wanted quality. The evaluation of the progress should be a consistent process

- Act:: Once the results are evaluated, actions will be made to perfect the strategies. Auditing the information acquired to implement the knowledge in the upcoming projects and the continuous PDCA circle is the intention. At this stage the adjustments are taking into account the information created during the first stages of the PDCA, and will be used as the circle starts over again.

The most crucial aspect of the PDCA is the continuous evaluation of the performed work. Every time a process is done the company will have to check the quality and document deviations. Necessary steps will be taken to meet required standards. The documentation will be used in future projects to provide a confidence that errors will not reappear.

The practical use of the PDCA is many, but mostly it is the idea that has influenced other techniques and tools, some of them will be discussed during this article.

ISO 9001:2015

The concept of the QMS was originally based on assembly line productions, where there would be identical products produced repeatedly. Transferring this into the construction industry, where the nature of each project would be totally different was a bigger challenge. One of the strongest initiatives to help this along was made by the International Organization for Standardization (ISO). They developed standards for implementing QC in the industry. The most commonly used is the ISO 9001:2015, which is also the only one among the ISO Standards which can be certified to. It is not required to certify, but there are more then one million companies worldwide with certification.

Acquiring an ISO 9001 certification has become a way to prove the company's credibility, and in some industries it is even legally mandated to obtain one. The ISO 9001 standard uses several tools and ideas in their standards to provide their users with the following benefits:

- Organize processes
- Improve the efficiency of processes
- Continually improve

The concept of PDCA is one of the most important basis for the ISO 9001. Further, ISO 9001 forms the basis of many other tools and methods to provide a company with the Quality required to fulfill the three main goals mentioned. Taking the amount of firms using ISO 9001 into account it is clear that the standard has a big influence on the QC around the world.

Performing the Quality Control

What differs the modern QC from the traditional one is the supporting activities alongside the project, but also before and after. Thus, many of the tools and methods are used prior to the actual construction.

In the initial phase of the project, planning is important to utilize the benefits of QC. Identifying the potential issues and making a strategy is one of the first steps in QC. There are different tools to use for the planning, e.g. Benchmarking, Flowcharting, Cost-to-benefit Analysis or Cause and Effect Diagrams. Using these brings predictability to the project, using previous knowledge, overviews and analysis of the project to plan the QC to be as efficient as possible, thus applying the concept of PDCA. In this section the article will have a closer look at some of the tools provided to perform the QC.

Quality Plan

ASQ defines Quility Plan(QP) like this:
"A quality plan is a document, or several documents, that together specify quality standards, practices, resources, specifications, and the sequence of activities relevant to a particular product, service, project, or contract."

Thus the intention of the QP is specifying the use of and which goals to achieve with the QC. As well as creating a guidance for the QC it will also create a verification for the customer who have to rely on the contractor to provide the required quality. The QP should integrate the overall goals and strategic plans in the organization to the individual project, to provide an ongoing progress. It concerns aspects from top organizational level to the lower levers where the actual QC on site is executed. The subsequent sections will all be a part of the information provided in the QP.

Cost of Quality

When a company is working with QC it is important to look at what is called Cost of Quality(COQ). The intention with this tool is to look at the difference in cost between a project with failures and the costs of a project that runs according to plan with no deviations or failures. Thus, the goal is to eliminate all actions and processes that do not add value or improve the quality of the project. This is also one of the most basic ideas of the Lean philosophy which is trending in the construction industry today. It has also been an important part of the production industry since the mid 20th century. The COQ encourages all parties to reach towards a "zero-default-attitude". Second it is a way to measure the effectiveness of the Quality management. Does the implemented strategies work and is the QC good enough to fully utilize the value of their product.

Adding increased quality to a product traditionally adds more expenses too, increasing the cost. To provide the added quality without the extra costs the COQ is divided into four parameters to classify the costs:

-External Failure Cost
-Internal Failure Cost
-Inspection (appraisal) Cost
-Prevention Cost

Each of the classifications will look at different aspects of the economical impact on the quality system. Identifying the sources to the costs will help distributing the resources to where they are most valuable. Thus improving the efficiency of the quality management and also the areas where QC will give the greatest benefit. In the end, intentionally, the increased quality will not result in extra costs.

Cause and Effect Diagram

Figure 2 Illustration of a simple Fisbone Diagram

The Cause and Effect Diagram is also called The Fishbone Diagram or the Ishikawa Diagram. First the method addresses a problem. The intention is to find the causes and effects of the current problem. The processes affecting the problem are categorized and for each category the potential causes are listed. Visualized in figure 2, the typical setup for a Fishbone diagram is shown. The name origins from the shape of the diagram, looking like a fishbone. Usually the diagram is drawn on a whiteboard while the team members will discuss the situation and try to come up with a solution together.

The Fishbone diagram will be a good measure when the team is trying to identify the causes to a problem or when they are in need of new thinking. The Fishbone diagram can be used both as a tool to come up with solutions for a problem, but also work as a preventive action. The preventive effect comes from understanding the causes and effects creating the deveations and can be used in future projects. It can also be the basis of another method called Benchmarking.

Benchmarking

Benchmarking is a tool for comparing projects or companies relative to each other. It is a way for a company to realize their weaknesses and strengths compared to their market. It can also be used inside their business when comparing to previous projects. It takes the organizations Quality Plan or their strategics for QC and compares it to competitors or similar looking projects where the basis for comparison is good. The benchmark will be the comparing organization or the project. Using benchmarking is a good way to predict the possible issues or risk that one might encounter. Thus, giving the opportunity to plan ahead and taking the necessary precautions to prevent similar events. Also, it is possible to look at what has been done correctly and copy this into the organization. Benchmarking is also an important step to keep evolving. The organization can use knowledge acquired from others and use this to their own advantage. Unlike the other methods for QC listed in this article, benchmarking uses the advantage of competition to provide a better quality inside the organization. It is also purely a preventive action to plan ahead of quality compromising events.

Check Sheets

One of the most common ways to perform QC is by Check Sheets also referred to as Checklists. They give directions about what to control and how to do it. Using the construction of a concrete wall as an example. Typically parameters can be e.g. placement, height, reinforcement, form works etc. The sheets are created and adapted to each individual project. All controlled areas will be documented and stored for later auditing. The controls are directed towards areas where the companies know faults occur, often a result of the risk assessment, QP or Benchmarking. The Check Sheets is a combination of preventive and corrective QC. It is also considered one of the most basic and simple ways of QC, with only small amounts of planning required. On the other hand processing the information acquired from the Check Sheets requires a sufficient amount of work. Using the knowledge gained from the controls are important in future work. Check sheets are also dependent on the other supporting activities in the QC. To perfect the Check sheets it is important to use the previous mentioned methods, resulting in an ongoing development towards better quality.

Evaluation of the Quality Control

An important part of the ISO 9001 system or the PDCA is the evaluation after the project ends. Thule describes the process like this:

"A systematic and independent survey to determine whether the quality activities and their results are consistent with what is planned and whether they are efficiently implemented and appropriate for achieving the goals."

This can be done both internally and from a third-party view to get a completely objective result. It is common that customers or the risk holders do an assessment like this, to make sure their investments are safe. Furter, there are several ways to conduct the evaluation. Either by looking at the horizontal point of view where the separate systems or tools are being evaluated, or it can be done vertically where the system from start to end are being evaluated. Depending on the success of the project there has to be a decision on which to use. The evaluation can look at the system but also other parameters i.g. economics, professional knowledge, work environment etc. Everything to make sure the organization keeps progressing.

Limitations

To keep the progress in a company, reaching towards their goals, QC can be a good measure. However, QC has to be used correctly. As many of the different sections in the article has discussed, handling the information acquired is very important. If the company cannot take advantage of their new knowledge and transfer this to future projects, the development will not continue and the QC is not fully utilized. The modern form of QC is yet very dependent on the evaluation and planning, thus emphasizes the importance of handling it correctly.

Communication is important in any company, especially when it comes to meeting their customers. Defining what is good quality and what is not, can be essential to the success of a project. If the company's perception of good quality do not fit the customers requirements for quality, the QC would be worthless. It is therefore important for all parties to communicate what their expectations are beforehand to avoid any disagreements. Communicating these standards within the company is equally important.

A third limitation is the costs of QC. Using extended QC with the accompanying methods and tools can be very expensive. If the company spend more money and time on the QC then they make up for in failures the implementation will just act against its purpose. Before implementing the different tools and methods there should be done research by the company to decide the benefits of the QC. After all, the company has to make money.

Having systems and methods to provide a good QC would in many cases be beneficial for the company. However, the idea that quality is important has to be implemented in the mindset of every employee in the company. Just following standards like the ISO 9001 or other tools without the understanding of why they are used does not engage in progress. Everyone involved in the process has to be committed and reach for their common goals. The work culture and environment is focus areas to provide the workers with a strong focus on quality.

Annotated Bibliography

Books:

Chris Hendrickson, (2000), Project Management for Construction Fundamental Concepts for Owners, Engineers, Architects and Builders, Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh

The book concerns basic Project Management. It is directed at project management in construction with each chapter explaining a different topic within the subject.

Torill Evy Thune, Kvalitetssikring og internkontroll i bygg og anlegg, 4th Edition(2017), Byggnæringens forlag

The book concerns different basis of Quality Assurance and Quality Systems. It discusses both the basics and further on different approaches to different subjects.