Metal Retrofit
Roofing System

Better Than a Metal Replacement Option

Metal Retro fit systems, also know as Flute-Fill, offer a much more budget friendly replacement option for metal roofs. Metal roofing systems begin to fail due to expansion and contraction over time that leads to worn out fastener connections. Older metal roofing systems were designed in a way that left the fasteners exposed, and when replaced with a similar metal roof, you will find that exposed fastener systems do not come with a 20-year material warranty. And because of the higher costs of replacement metal, a single ply metal retrofit roofing system can be the most cost effective solution that also provides a 20-year warranty.

Visual Process

metal roof in need of repair
Before: metal roof in need of repair.
coverboard over metal flute fill
Flutes filled with insulation with coverboard over the top.
tpo metal flute fill
Finished roof with new TPO membrane over metal.

Flute- Fill Installation:

A TPO metal retrofit roofing system is where the channels of the metal roof are filled with an EPS insulation. The EPS flute-fill can be cut to fit any metal roof flange profile (square, tapered, or profile cut) to fit between the roof ribs. A second layer of insulation or cover-board is installed and secured to the roof deck to ensure a flat even surface to increase the R-Value.

The next step includes the installation of a TPO roof membrane. As part of this process, the membrane will be mechanically attached directly to the purlins (roof structure) and the fastening rate around the perimeters will be increased to meet or exceed all design, wind up-lift requirements and warranty criteria. All laps and joints will be fully heat welded to completely seal the membrane. The pipes and penetrations are also heat welded to the roof’s membrane to create a continuous waterproof system.

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In Summary

The Benefits of a Metal Retrofit include:

  • More cost effective than a metal replacement to achieve 20-year material warranty
  • Reduced maintenance – no future issues with fasteners or end seams.
  • Improved energy efficiency with higher R-Value
  • Greater roof stability
  • Maintain existing metal roof vs expense & waste of removal.
  • Finished product provides for an esthetically appealing building
  • Increase the overall property value


WNC Roofing utilizes a Carlisle 60 mil TPO which has a wear layer that is 33% thicker than that of a 45 Mil TPO and comes standard with a 20-year warranty certificate issued by the manufacturer. 

A post-installation inspection is conducted by the manufacturer upon completion of the project to certify the necessary manufacturer’s standards for the 20-year warranty and WNC Roofing provides a two-year workmanship warranty to cover all installation aspects.

Recent Metal Retrofit Projects