Technical Blog

Welcome to John’s Blog. Answers to frequently asked questions are periodically posted here. The objective is to share information about PVC pipe with readers as well as with utilities, design engineers and pipe installers. The blog provides the latest information on PVC pipe design, installation, and application for water and wastewater infrastructure projects.

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John Houle: Senior Technical Consultant, PVC Pipe Industry

John Houle holds a Master’s Degree in Civil Engineering from the University of Missouri and an MBA from the University of Oregon. He has more than 25 years of experience in the plastic pipe industry in applications engineering, market development, forensic analysis, technical writing, and standards development.

Large-Diameter PVC vs. Fiberglass for Sewer Projects

Posted By John Houle on May 7, 2026

PVC and fiberglass (FRP) compete in the 24- to 60-inch sewer pipe markets. Field experience has shown that FRP is much more sensitive to pipe deflection (similar to ovalization) under earth and/or traffic loads, which has resulted in failures. As a result, the PVC Pipe Association has published a document that reviews design and installation practices for PVC and FRP sewer pipe.

FRP does not respond as well as PVC pipe to deflections when buried. The deflections that cause FRP to crack are not an issue for PVC, since deflections that impact FRP remain well within PVC pipe’s safety factor. Due to this failure mode for FRP, it often needs to be designed using higher stiffnesses compared to PVC. For PVC pipe there is never a need to specify a higher stiffness.

This failure mode for FRP at deflections which can occur under many field conditions has resulted in catastrophic failures costing millions of dollars in repair and replacement costs for utilities.

Read the paper Evaluating Large-Diameter PVC versus Fiberglass for Sewer Projects.