We had a recent inquiry about the cost and performance of traditional cedar shakes and steel or aluminum shakes emulating the look of cedar. It's a good question, and we're happy to answer it.
When you compare the price of metal roofing formed to resemble wood shakes to the real thing, there are quite a few considerations.
Appearance: Nothing but real wood looks EXACTLY like cedar shakes, but metal can offer a very similar architectural element. If only wood will do, then you have little choice. If you're interested in the look and feel of a wood shake with something a little more regular - but much more permanent - then metal offers a beautiful alternative.
Lifespan: While cedar shakes have been used for roofing for centuries, most versions of the material available today are a far cry from the cedar shakes used long ago that lasted generations. In a nutshell, modern conservationism has meant that the vast majority of the cedar lumber used for wood shakes today is of the "second growth" quality. This lumber is harvested from re-planted trees that are spaced to encourage fast growth. Generally speaking, the faster a tree grows, the less dense the grain, and the less dense the grain, the lower the quality of the wood. Add to this the fact that in order to yield more shakes from a given log, cedar roofing shakes are usually cut and ordered much thinner than was once the case. The bottom line is that while 50 years ago, many cedar shake roofs in many parts of the country would last 50+ years, today a lot of roofers make their living replacing wood shake roof that haven't made 20 years. Metal roof tiles and shakes in most regions have lifespans approaching and exceeding 100 years, making the life expectancy of the average metal roof four or five times that of wood shakes today.
Fire safety: Wood roofs may be the most dangerous choice in locations prone to fires. Metal is a non-combustible material that simply won't burn in a fire. While it's possible to purchase "fire treated" wood shakes, such treatment raises the price significantly - to the point that a heavy, fire-treated wood shake roof can cost more than a metal roof. In addition to the cost, there is evidence that the treatment that reduces the combustibility of wood roofing degrades with exposure to the point that it stops offering any protection. See this link for more discussion:
Bottom line: When considering metal shake roofing or wood shakes, it's very important to notice what level of quality you're using for your comparison. While wood shakes can cost as little as $3 a square foot to install, they can easily reach $10-15 if the best version is chosen. Similarly, metal shake roof installations can vary significantly. However, you can expect to pay in the range of $5-10 for most typical applications. While it may not look exactly like wood shakes, the extra lifespan and safety of metal shakes make them a great choice.