What Is the Difference Between QA & QC on Construction Projects?
Construction project quality assurance, or QA, and quality control, or QC, are two fundamentally different processes with different goals and purposes. Whether you are the owner or the contractor, you have to use the correct methods to fulfill your role in ensuring high-quality results. When each of the project participants knows what aspects of QA and QC fall within their areas of responsibility, they can execute the project to the required standards.
In the design phase of a construction project, the quality assurance program focuses on the procedures that the construction company has implemented to ensure that the design meets quality standards. It specifies qualifications for designers, engineers and architects; signatures rules for drawing preparation, revision and approval; and quality standards for the materials proposed in the drawings and specifications. Quality control checks that the people carrying out the work have the specified qualifications, that the drawings are signed properly and that the materials to be purchased meet the specified standards.
A QA system sets up a process for determining which suppliers are qualified to deliver the required quality. It specifies whether visits of supplier facilities are required, whether the supplier has to have a QA program in place and whether testing of supplied materials is required. QC applies the process, makes sure the selected suppliers meet the qualification criteria and carries out any testing that is required. QC is responsible for corrective action if quality control personnel find that material is not as specified or does not meet the required quality standards.
QA specifies how to determine the applicable construction standards. Typically, a QA program sets up a process that allows you to evaluate a construction specification or project description to identify standards that will result in the quality the owner wants, in addition to satisfying legal and building code requirements. Quality control means verifying that the work and materials used satisfy the applicable standards as specified within the QA system. The QA program may include specific tests for the wood or steel used and for processes such as welding. It is the responsibility of QC to carry out such testing.
The application of QA procedures let you identify the characteristics that the completed construction project must have and the quality levels it must satisfy. For example, a building specification may require a thermal insulation level for outside walls. The QA program identifies the applicable standard and any testing that the standard requires. Once the project is finished, QC verifies that the outside walls have the required insulation levels and carries out any testing that is needed. QC is responsible for documenting the results and presenting them to the owner if required.