Metal Roofing California | Cool Roofing

There are many choices when it comes to roofing, but few choices have the distinctive look and durability of a metal roof and metal roofing in California has the advantage of being cool roofing to boot. Many different choices are available: corrugated sheet metal, aluminum, and copper are the most widely recognized examples. All of these have various strengths and weaknesses, but all share a high strength to weight ratio, a long life, and excellent water repelling ability.

Corrugated sheet metal is one of the most inexpensive metal roofing materials, and sometimes carries a bad reputation because of it. Initially, iron coated in zinc in a process called galvanization was the used, and it had a tendency to corrode if any of the zinc wore off. Since the development of iron roofing in the 1820's, manufactures have switched to galvanized steel and stainless steel, both of which are stronger and more weather resistant. Corrugated metal roofs are often used when a strong roof is needed, and cost is a large consideration.

Copper roofs are very distinctive, starting with a bright shine which fades into a green patina. The green is actually a copper oxide, the result of the copper corroding when in contact with the air. The patina protects the metal from further corrosion, making copper roofs especially durable. Because copper is fairly flexible, it can be used on curved surfaces, although it is more susceptible to impact damage than other metals.

Aluminum is the lightest of the commonly used roofing metals, and one of the most corrosion resistant. Aluminum is also one of the best thermal conductors and combined with its high reflectivity, can help keep a building cooler in warm climates. Unfortunately, Aluminum is one of the most expensive roofing materials, which makes it unsuitable in many situations.

All metal roofs have many advantages over more conventional choices. Sometimes referred to as A Lifetime Roof because of its last lasting qualities most metal roofs can be expected to last for over thirty years. Metal is of course fireproof, making it an excellent choice in fire-prone areas and in close quarters with other buildings. Metal is flexible, so it can be used to create curved waterproof surfaces where shingles or tile would not work. Its high weight-to-strength ration makes it an excellent choice in harsh conditions, where other materials would be damaged. In what is probably one of the most important considerations, metal is extremely durable compared to other types of roofing, making it a good choice for many applications.

There are a few disadvantages to a metal roof-although they are strong, they are also heavy and are therefore unsuitable for an application where weight might be an issue. Metal also expands and contracts with temperature, so care must be taken to allow for movement of the roof in hot and cold. Some people find the look of metal roofs unattractive and copper and aluminum roofs can have a reflective surface that many find obnoxious. Finally, metal roofing may be more expensive than other roofing types. Despite these limitations, metal can be the best choice for a durable, long lasting roof.

Other Places to Visit

Title 24 Blueprint Newsletter Issue # 83 on Cool Roofs
(PDF file, 1.4 megabytes)

Energy Videos on Cool Roof
California Energy Commission

Cool Roof Rating Council

Cool Roofing Materials Database
Lawrence Berkeley Laboratory

ENERGY STAR® Reflective Roof Products
Product and manufacturers lists.

FLEX YOUR POWER
Product Guide on Cool Roofs and California Rebates

Heat Island Group
Lawrence Berkeley Laboratory