Both quality assurance and quality control in a construction project are aimed at ensuring quality of the final product - the building. Even though they are often used interchangeably and listed together as QA/QC in construction consulting companies’ service offerings, Quality Assurance and Quality Control are fundamentally different practices.
Why should anyone care about the difference? There are several reasons why project owners, contractors and other stakeholders should understand the distinction. Quality control checks whether the final product will meet customers’ requirements, whereas quality assurance is a strategy of prevention. It identifies and reduces risks for defects. QA is a quality management process that could significantly reduce potential for claims.
Since both of these valuable practices, QA and QC, are directed at ensuring quality, it pays to determine what exactly quality is. Quality is a measure of excellence in relation to customer/user requirements. A quality product or service is free from defects and significant variations and it is the result of a process that adheres to measurable and verifiable standards that achieve uniformity of output. Ensuring quality is a strategic measure in construction against unwanted results, like claims.
Quality Assurance (QA) is a set of planned and systematic activities which are laid out before a building project starts. The aim of this activity plan is to give confidence that quality requirements will be fulfilled. We can put it simply, like this:
Quality Assurance is planning to do the right things at the right time and the right way.
Quality Control are observation techniques and activities which aim to identify whether the final product actually fulfils customer requirements. Quality Control also identifies the need for corrective measures. In other, simpler, words:
Quality Control monitors work as it happens and ensures that the results satisfy the requirements specified.
Quality Assurance is about a plan. It is carried out before the construction project starts. Quality Assurance is a process that manages for quality. QA lists the processes, standards and policies that need to be carried out and ensures they are known to the people who need to know them.
The key elements of Quality Control are observation and activity. Even when you have the best plan and system in place (that’s what Quality Assurance does), you still need to monitor the work as it occurs to make sure the results are what you expect them to be (Quality Control domain). Quality Control verifies the quality of the output.
Quality Assurance and Quality Control are different, but complementary part of a larger concept – Quality Management. Achieving success in a building project requires both QA and QC.
Why? If you only lay out plans that define processes and procedures to be carried out (QA), you may have an excellent plan, but the result of those processes and procedures doesn’t get checked for fulfilment of customer requirements (QC).
On the other hand, if you only conduct testing and observation to check the quality of results (QC), you don’t have the vision of the whole picture. The tests won’t be repeatable, you won’t be able to understand the problems in your testing and eliminate them and finally – you fail to improve the general way of delivering the product.
If either QA or QC are left out, the final product (in the case of construction, it’s a building) is not likely to meet customer requirements or business needs that prompted the construction project.