It can last 30-40 years. This is longer than the expected lifespan of a composition roof. With proper maintenance and depending on what it’s exposed to, these roofs are some of the more durable roofs out there. While they may cost a bit more upfront, getting up to double the lifespan of a composition roof along with the natural luxurious look and feel of cedar might give cedar shakes more value for the money than composition roofs for some home or business owners.