Quality Control vs. Quality Assurance

Vol. 110 | February 28, 2017

Many professionals in the construction and AEC community frequently use the terms Quality Control (QC) and Quality Assurance (QA) interchangeably. Both are important, but they serve a different purpose and each has a different place.

The first step in doing a project or task correctly is developing a quality control plan or process. Parts of this plan include things like understanding the materials that are used, the necessary training of the people performing the work, and the conditions required to execute the work correctly.

A good example is the knowledge not place concrete in the rain. Additional water reduces the strength potential of the concrete mix and makes finishing more difficult. Rain also increases the risk of accidents and may interfere with the use of electric vibrators and finishing equipment. But if the members of the placement team do not all know this then someone may push to “go ahead” citing schedules and looming deadlines.

This knowledge comes through training, both formal and informal, on how to place concrete correctly. This training and documentation of the training is part of the QC Process. QC is a constant awareness of those facts and processes and typically lies at the contractor and subcontractor level where the work is actually getting done.

The Quality Assurance component typically comes from an outside third party agency. The job of the QA is to validate and verify that the QC process is working and appropriately implemented, having the best trained people and the best conditions possible. QA is the looking over the shoulder of the QC process, making sure the QC plan, written by the people doing the work, is actually being followed and is creating the correct result.

Bill Ciggelakis, P.E.
Principal-in-Charge, Construction Services

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Related topics: 2017 | Due Diligence