March 8, 2021

Understanding Quality Control Versus Quality Assurance for Construction Projects

By Caroline Smrokowski, Jason Wilen, AIA CDT RRO – Klein and Hoffman

As a Building Owner, Facilities Manager, Property Manager, or Board Member you likely choose Contractors for projects ranging from interior renovations to façade repairs and roof replacements. Though you may have little to no construction knowledge, there is one simple question you should always ask a Contractor prior to selecting them for a project:

How do you ensure (the roof, the window, the flooring, etc.) gets installed correctly?”

Although this question may seem oversimplified and obvious, it initiates an important discussion about a Contractor’s quality control process. Two important terms to understand when having this discussion and determining if a Contractor is right for your job is quality control versus quality assurance. Quality control is a regular evaluation of the work performed by the Contractor to catch and correct errors in the work.

Quality assurance, on the other hand is performed by the Owner or more often a design professional hired by an Owner such as an Architect or Engineer (A/E), as a planning and preventative measure to ensure that the Contractor’s work meets the design intent at the end of the project. As forensic Architects and Engineers, Klein and Hoffman does work on building envelope restoration and rehabilitation projects. We often see inadequate quality control performed by Contractors, where the Contractor’s superintendent or project manager relies on the word of the crew members that the work is installed correctly, rather than having a dedicated quality control person regularly checking the work of the crew. The Contractor sometimes relies solely on job site visits by the A/E or material manufacturer’s representative, which are performed occasionally, to catch all the mistakes and inadequate construction. Relying on quality assurance visits as a substitution for the Contractor’s quality control process is not a good deal for Owners as both quality control and quality assurance are often needed for an installation to be successful.

Roof System Example
As an example, we recently designed a roof system replacement and performed quality assurance for a university laboratory building. Our role included an investigation of the existing roof system, preparation of construction documents, and services during construction to review in-progress work. As part of our quality assurance process, we required the Contractor to coordinate site visits with the roof system manufacturer to review unique conditions and confirm steps moving forward such as surface preparation to ensure proper adhesion of the new roof system. One of the challenges with this project was the maze of existing duct work overhead and the significant number of curbs and penetrations to be sealed. (See Photo)

In completing our quality assurance work we identified many instances where material was not correctly installed and was marked for re-installation or touch-up. This effort was time-consuming and caused a delay in the completion of the work. Some leaks occurred because of the deficiencies. Due to the complexity of the project and the multiple types of conditions, a rigorous quality control process by the Contractor would have identified issues early-on and allowed for adjustment to installation practices and eliminated costly and disruptive rework. While the A/E’s quality assurance process did untimely allow for correction of improper installation, the extra cost to the Contractor in rework and to the Owner in additional A/E fees and additional disruption was not avoided. Also, if an A/E was not part of the process, the improper construction may not have been discovered.

The process noted in the roof system replacement example is relevant for almost any construction project and is applicable for jobs where an Owner is not also using an A/E. Engaging with potential contractors and understanding their quality control process (or if they even have one) provides an important indication how successful they likely will be.

For more information about quality control and quality assurance roles and responsibilities, The National Roofing Contractors Association (NRCA) offers a number of publications listing quality control and quality assurance guidelines and best practices for the application of various membrane and shingle roof systems. As an Owner, having an understanding of quality control and quality assurance and discussing the process with potential vendors will help you choose the appropriate Contractor for your project. These publications are available on NRCA’s website: https://www.nrca.net

Download a copy of this article here: https://issuu.com/kleinandhoffman/docs/understanding_quality_control_versus_quality_assur