Copper is heavily employed in the construction industry. It is commonly found in buildings because it is waterproof. This makes it suitable for cladding, roofing and plumbing. It is also applied in freestanding structures because of its light weight and durability. Lightning rods and roofs are often built of copper. As a lightning rod they help divert natural lightning from striking the edifice. It is redirected to the ground. Copper based welding arcs are made by soldering the metal. The same method is used for building structures.