Retrofit refers to a complete, fully engineered metal system designed for installation over existing flat or sloped roofs. For architects and contractors retrofit presents an opportunity to expand business. For building owners it provides an enhanced appearance for existing buildings, ease of installation in new construction, reduced environmental impact, and improved energy efficiency.
For more than 25-years, retrofit has been a cost effective solution for problematic roof geometry, maintenance issues and outdated appearance. Now, thermal efficiency and energy savings are key reasons for retrofit applications. The use of metal roofing is an added benefit since it has a service life of nearly double its closest competitive roofing system, which currently is modified bitumen or built-up roofing (BUR).
The use of metal in a retrofit roof may also qualify for points in certain green building certification programs. Metal is made from recycled materials and is fully recyclable. It has reflective and emissive benefits, so it reduces heat gain and the building’s carbon footprint. Installing a retrofit system often does not require removal of the existing roof or wall material so it also reduces landfill waste.
Retrofit systems are fully engineered to ensure the integrity of the project. During installation the building interior is not exposed to outside elements or contamination.
All retrofit systems create design opportunities for improving thermal resistance, offering a balanced ventilation system, enhancing a building’s appearance and reducing maintenance.
Low slope installations are usually utilitarian and economically driven and offer a roof pitch from ¼ to a maximum of 2:12. Although a low slope application does not typically add curb appeal, it can improve discharge of rainwater.
Steep slope installations have a slope greater than 2:12 and are more architecturally driven. Energy efficiency features can also be incorporated in steep slope installations, such as cool roof coatings, and renewable integrated energy systems.
When steep sloped metal roofs are installed over conventional membrane, tear-off of the existing roof is normally not required and removal of existing roof insulation may not be necessary. According to the International Building Code (IBC-2006) an existing roof does not have to be removed when reroofing with a standing seam metal roof system that is secured to the existing building structural support system.
Adding certain elements to the retrofit system can enhance the energy efficiency of the roof. These elements may include extra insulation, installation of a radiant barrier, creating more ventilating space and adding solar technologies.
A major energy benefit in a retrofit roof system is the increased natural ventilation, especially in steep-slope applications. This convection inherent in a retrofit application is called above sheathing ventilation (ASV). It allows heat to dissipate through the ridge vent in hot weather and acts as an insulating layer in cold weather. With ASV up to a 30 percent reduction in heat gain through the roof is possible. The reduction in heat gain can increase to 45 percent when a “cool” metal roof surface is used. The use of ASV may also qualify the building for Federal tax benefits.
Adding solar systems to the retrofit design may also qualify the building owner for Federal solar-energy tax credits. Solar systems can be focused on heat recovery, water heating or power production. Since the service life of a metal roof is longer than that of a photovoltaic solar system, mounting a system on a metal roof provides savings of 24 percent to 43 percent compared to a conventional roof system.
Using a standing seam metal roof with a PV system also offers Federal solar-energy tax credits, and state and local tax and utility incentives depending on location. In addition to these immediate savings, the building owner will benefit from reduced energy use throughout the life of the PV system.
Whether there is need to retrofit a roof, retrofit metal roofing systems offer solid engineering, improved appearance and long-term value.