For questions about all types of metal roofing systems.
Metal roof claddings are used in a variety of applications, although they are more commonly found at the extreme low end (sheds, barns) and high end (commercial/institutional/multi-family sloped roofs) of the roofing world. There are several different metal roof technologies, deployed in different applications:
Corrugated metal panel roofing is used as a combination cladding and decking system in low-end/low-cost applications such as barns and storage sheds where minor water leakage is considered acceptable and rust is not a concern. These panels are typically made from sheet steel, and have an expected lifespan of under 20 years.
Standing seam metal roofing is used in residential and commercial/institutional applications. It is designed to clad over a waterproofing (barrier) membrane, while protecting it from UV, hail, and other damaging factors; however, it typically requires professional installation. It can be made from a variety of materials with varying life spans:
- Galvanized steel is the shortest-lived and least expensive material. Lifespans range from 20 to 40 or more years depending on conditions.
- Aluminum or Galvalume™ (aluminum clad steel) is longer-lived but more costly. 30 year lifespans are not uncommon for these materials.
- Copper is the costliest roof material, but provides superb longevity with 50+ year roofs easily achievable.
Metal shingles provide an easier-to-install alternative to standing seam roofing, with lifespans comparable to the shorter end of standing seam. Again, these are used over a waterproofing membrane.
Soldered seam metal roofing has been used in the past, and may still be found on historical buildings. While its longevity is superb (with 100+ year old roofs still in service), thanks to the robustness against leakage provided by soldered seams and the inherent corrosion resistance of the copper material used, the high cost of both materials and labor renders standing seam a much more attractive option in the modern world.
Metal roofs have the advantages of being hail-resistant (hail damage to metal roofing systems is mostly cosmetic), more reflective (which reduces solar heating of the roof), and fire-resistant; however, their high capital cost and limited installer base keeps them from being more widely used.