The 25-year-old trapezoidal standing seam roof on the Metal Sales Manufacturing plant in Rogers, Minn., sustained hail damage during the summer of 2020. Initially, the plan was to tear off the damaged metal roofing and replace it with a new metal roofing system. To avoid a stoppage in production, further discussion led Metal Sales to install Roof Hugger sub-purlins on the damaged roof and attach a new metal roofing system to those sub-purlins.

“The disruption of production for several months was not an option,” says Kevin Roehl, production manager at Ebert Companies. “Using the Roof Hugger system allowed operations in the facility to continue normally during the reroof.”

Ebert Companies installed 25,450 linear feet of Roof Hugger’s Model-T sub-purlins on top of the existing roofing.

The Task

Roof Hugger was charged with providing a structurally correct framing system to properly support the Seam-Loc 24 standing seam metal roofing and trims from Metal Sales. Retrofitting existing roofs installed using tall clips presents a special challenge since the panels “float” one inch or more above the existing purlins. Roof Hugger created, tested, and patented a unique sub-purlin system specifically designed for these panels that control positive, negative and rotational forces. 

Ebert Companies installed 25,450 linear feet of Roof Hugger’s Model-T sub-purlins on top of the existing roofing. The 16-gauge, 50 ksi, G-90 galvanized Model-T sub-purlins were designed and tested for existing metal roofs. 

The sub-purlins were mounted on tall clips in addition to special stand-off fasteners for the structurally correct attachment of the Huggers to the structure, standard fasteners for joining the Huggers to each other and attaching the other structural components and 16-gauge structural hat channels in various heights. 

Metal Sales chose a 24-gauge bare Galvalume Seam-Loc 24 roof panel [105,000 square feet] with Ocean Blue flashing and trim. 

Roof Hugger created, tested, and patented a unique sub-purlin system specifically designed for these panels that control positive, negative and rotational forces.

Friction Workaround and Future Planning

The one issue Ebert ran into during the reroofing process was replacing the existing smoke hatches that were not curb mounted. Ebert purchased and installed new curbs and curb-mount smoke vents from LMCurbs, a manufacturer of roof curbs, roof hatches, and skylights.

“Everything turned out very well,” Roehl says. “We were able to leave the existing roof in place and not cause any disruption to their production area and not have to worry about keeping the facility dry if we would have removed the existing roof.” 

Roehl added that the owner made note of how insulation added between the roofing systems helped keep the facility warmer during the winter months.

Metal Sales is considering the option of adding photovoltaic panels to the roof in the future to help reduce or even eliminate electrical costs. The Roof Hugger sub-purlins and Metal Sales metal roofing are engineered to handle that load.

Roof Huggers maintain the integrity of original design loadings; achieve "thermal break" air space between old and new roof sheets, and allow for optional insulation.

The Upshot

Roof Hugger’s notched sub-purlins allowed new metal roof panels to be replaced over an old metal roof. They can be used over screw-down or standing seam roof systems and can accommodate new standing seam or screw-down panels. 

Roof Huggers maintain the integrity of original design loadings; achieve "thermal break" air space between old and new roof sheets; allow for optional insulation; and are laboratory and load tested. 

For more information on metal-over-metal retrofit reroofing, contact Roof Hugger at 800-771-1711 or visit roofhugger.com.

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