• Lead is a material that has been around for centuries, thanks to its availability and malleability. Its use in building has also been around for centuries. Plenty of castles and mansions still exist in Europe, and, among other uses, you can find lead in their windows, on their roofs for flashing and, even, in their pipes for plumbing. It was not until the 20th century that concerns about the poisonous properties of lead made its use more carefully regulated. While an effective material for flashing because of its longevity and ability to repel water, it is worthwhile to consider other flashing alternatives when replacing or building your roof.
  
  

Polyisobutylene Flashing

• This flashing, like lead, is malleable and able to take on the profile of any roof to which it is applied, thereby, keeping its ability to prevent the introduction of water into the building. This material is also able to weather extremes in temperature, which is especially important in places where the cold of winter and the heat of summer are present. Polyisobutylene flashing has another benefit that lead cannot claim: It is very easy to install, requiring only scissors or a knife to cut and included adhesive strips to adhere it to the roof.
  
  

Copper

• Copper is a common flashing material. It works as well as lead in that it repels water well, and you can solder it easily if you have to make joints or connections. The main detriment is its cost; copper costs more than lead for use as flashing. However, its durability makes it well worth the consideration.
  
  

Aluminum

• Aluminum is a good alternative to lead in that it is easy to work with and less expensive than copper. However, you cannot solder it while you are working on the roof ("in the field" in building-speak). To make joints or connections, you need to use fasteners, and seal it with caulk.