Building a stronger metal-over-metal retrofit

By The Coffee Shops®. 

Roof Hugger’s approach focuses on structural attachment, code compliance and long-term performance. 

When building owners choose a metal-over-metal retrofit, the supporting sub-framing system plays a critical role in the performance of the new roof. Roof Hugger’s sub-purlin system is designed specifically for installation over existing metal roof assemblies, providing a foundation for a new metal roof without the expense and disruption of a complete tear-off. 

Roof Hugger sub-purlins are engineered to fit a wide variety of existing metal roof systems and provide direct attachment to existing structural members. Architects and specifiers enjoy this feature because it allows for numerous new roof panel options. Roof Hugger’s retrofit assemblies have undergone extensive testing using multiple combinations of new and existing roof panels.  New systems, provided by almost every major metal roof panel manufacturer, have been installed on more than 130 million square feet of existing metal roofs, with millions of additional square feet added annually. 

The system offers several practical advantages. Roof Hugger sub-purlins can be manufactured to specific heights, creating room for additional insulation or helping address roof elevation changes that may affect weather-tight connections. They can also add strength to existing purlins and be designed to support additional photovoltaic weight plus compliance with current wind and snow-load requirements. 

Another notable benefit is the ability to upgrade an existing screw-down metal roof to a standing seam roof system. This panel and sub-framing design accommodates expansion and contraction while supporting long panel runs, making it suitable for modern roofing applications. This adaptability allows building owners to invest in their structure long-term without having to weigh the downsides of a full roof removal and replacement.  This combination also makes future photovoltaic systems viable by strengthening the purlins and providing a roof that does not need to be penetrated when adding solar panels.  

Roof Hugger products are manufactured in the United States from high-strength 16-gauge, 50 ksi, G-90 galvanized steel. Combined with extensive testing and engineering flexibility, the system is positioned as a long-term retrofit solution designed to meet current building code requirements while extending the service life of existing facilities.  

Learn more about metal-over-metal retrofit systems and the role sub-framing plays in roof strength.