Plant inspections have been an integral part of the Polymeric Exterior Products Association’s (PEPA) VSI Product Certification Program since its inception in 1998. These inspections play a critical role in maintaining quality standards for certified vinyl and polypropylene siding products.
Initial inspections are coordinated with plant personnel when a new plant is being approved, and follow-up inspections are conducted annually at qualified plants. After issuing Product Certification Listings (PCLs) and Product Evaluation Reports (PERs), the Certification Body (CB) works with its inspector pool to continually visit qualified plants across North America.
“This is a foundational aspect of the Program to ensure ongoing compliance and quality control consistent with the VSI Product Certification Program’s standards,” said Sara Krompholz, PEPA’s Senior Director, Technical and Certification.
What Do Inspectors Do?
Inspections take place twice a year and were traditionally unannounced. All plant inspections include the following activities:
- Ensure the quality manual is being reviewed annually and kept current by comparing the version on file with the CB to the copy maintained at the plant.
- Pull product samples to send to the certifying body for testing.
- Witness production extrusion taking place on the plant floor (i.e., the production of vinyl panels with multiple lines running).
- Check carton labeling for proper use of the VSI Certification Mark.
- Look at disposition records for non-confirming materials.
- Witness impact testing onsite by the plant’s quality technicians.
- Capture any quality documentation that needs to be returned to the certification body for processing.
All inspectors use an approved checklist when reviewing a plant site and other documentation to capture necessary information. Their findings are included in a final inspection report issued by the CB, and follow-up testing data is also reported to the plant facility. In addition, all inspectors are employed by the respective CB.
What Makes Inspectors Qualified?
Inspectors receive specialized training on PEPA’s VSI Product Certification Program conducted by their CB employer. This includes a thorough education on all four product types (and their manufacturing processes):
- vinyl siding (ASTM D3679),
- insulated vinyl siding (D7793),
- polypropylene (D7254), and
- backed vinyl siding (D7445).
Ongoing training for inspectors continues as the Program evolves. New inspectors often shadow seasoned inspectors on the first few visits so that they are fully prepared to conduct their own plant inspections. All trained inspectors have a wealth of building and construction experience and commonly have direct industry experience.
How Ongoing Inspections Ensure Certification Compliance
Thanks to semi-annual plant inspections, there is no ability to “cheat the system.” And because of proactive PEPA members who contribute staff and product expertise to the Product Certification Oversight Committee (PCOC) and the Product Certification Work Group (PCWG), the Program remains relevant and robust.
According to Sara, it’s the PEPA members who understand how important certification is, given the history of overcoming negative perceptions about polymeric cladding.
“Our members treat this like a ‘self-evaluation’ even though a CB conducts the inspections,” Sara noted. “Without ongoing compliance, the Program would not have continued confidence to issue or update certification. Since the VSI Product Certification Program was relaunched (as ISO/IEC 17065-accredited) in 2021 with deliverables such as PCLs and PERs, it’s even more critical to have these quality control checks.”
Sara added that PCLs are renewed on an as-needed basis, while PERs are renewed annually.
Moving Forward with Industry-Driven Confidence
In 2026, PEPA’s VSI Product Certification Program will transition to announced plant inspections.
A total of 23 plants, representing eight PEPA member manufacturers*, will make inspections more seamless with fewer plant interruptions. More importantly, the efforts and influence of PEPA members in evolving and continuously improving the Program have made unannounced inspections unnecessary.
“The Program is now in its 28th year,” Sara said. “We didn’t have manufacturer confidence back in the day. But today, we don’t have the sample failures and variances we once had. We now have a healthy Program, and everyone is aligned. Our members not only know the rules and benefits of complying and maintaining quality control, but they also helped us write them.”
* How 17020, 17025 and 17065 work together for product certification –
17020 – accreditation for an inspection body
17025 – accreditation for a testing laboratory
17065 - accreditation for a certification body.
Three CBs are now involved with PEPA’s VSI Product Certification Program, and each offer expertise in the areas of inspections, testing and certification.