Cost

• Standing seam metal roofs cost a lot more than other roofing materials, both in terms of parts and labor. Each metal sheet must be measured and cut to order and the installation itself is best done by a professional contractor who knows how to prepare the roof to take standing seam metal plates -- otherwise, the risk of damage is high. This knowledge, plus the cost of ordering custom plates, means standing seam metal roofing is expensive.
  
  

Installation

• Installation of a standing seam metal roof is best done by a roofing contractor trained and experienced in the installation of metal roofs. The roof needs to be cleared of any existing roofing materials, nails and other problem materials that can interfere with the metal roof once it is laid, and potentially lead to rust or other damage that causes the roof to fail before its time.
  
  

Time

• Standing seam metal roofs are expected to last around 50 years when undamaged and cared for properly. Although several metal roofs have lasted for over 100 years and continue to function correctly today, the majority of installers will only guarantee a standing seam metal roof for between 20 and 50 years.
  
  

Rust

• Metal roofs expand and contract with the heat and cold of the atmosphere, which naturally causes movement of the metal sheets. If a metal roof is installed over an existing roof, such as asphalt or single, then the surface of the metal will scratch as it moves, leading to rust. In addition, any loose nails or other debris trapped under the metal roof will also scratch the metal, leading to rust.