September 6, 2013


by kbuchinger

As most metal roofers know, there are literally billions of square feet of metal roofing in the U.S. nearing the end of its service life.  So, when it’s time to reroof these buildings, what should one do? Should you tear off the old roof and start over or simply remove the fasteners from the existing roof and install another roof over it?

Metal-Over-Metal Retrofit Considerations

There are a number of issues a roofer will have to deal with when it comes to metal-over-metal retrofits, but listed below are a few where the use of a Roof Hugger system may help resolve:

  • Does the existing roof need an insulation upgrade?
  • Are there workers in the building that would be at risk if the existing roof is completely removed for installation of a new roof?
  • Do current code requirements dictate the addition of closer fastener/clip spacings?

Retrofit Roofing Benefits

Chances are that roofs installed 40 or 50 years ago did not have much insulation under them. These days, everyone is concerned about heating and cooling costs.  Certainly, a better insulated roof would help in the majority of cases. The use of Roof Hugger systems allows you add blanket, rigid and/or reflective insulation between the existing and new roofs.

By using Roof Huggers, the existing roof can be left in place. This provides a safer environment for both workers inside the building and the roofers as they install the new roof. With the existing roof left in place, there are typically no “leading edge” safety issues. Leaving the existing roof in place will save a substantial amount of labor and eliminate hauling the old roof off.

Reroofing Code Requirements

Current code requirements may dictate that the new roof be able to withstand greater uplift pressures  than was required when the building was originally built, particularly in the edge and corner zones of the roof where the pressures are higher. In some cases, the use of Roof Huggers may increase the existing building’s purlin load capacity by providing additional brace points. When this is not enough, the Roof Hugger system has the ability to provide additional attachment points between the existing purlins.


The use of Roof Huggers also allows a building owner to incorporate technology such as solar thermal into the new cavity between the existing and new roofs. Solar thermal technology, used for preheating water or to help heat the inside of the building, is the most efficient use of solar technology that one can employ.

As you can see from all these benefits, Roof Huggers should be considered for any metal-over-metal retrofit to ensure that your new metal roof performs to its greatest potential.

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