The answer to that question depends on the type of roof covering, how well it was installed, and certain environmental factors specific to the location of your house.
For purposes of this question we will not discuss any structural issues and focus on the roof covering, which is comprised of the exterior covering and any type of underlayment. The underlayment is the thin, paper-like material installed on top of the roof decking, which is usually plywood, oriented strand board (OSB), or nominal 1”x6” boards in older homes. On older homes the underlayment would likely be an asphalt-impregnated heavy paper, often referred to as “felt paper”. It has been used for many years and under the right conditions can last decades. More recently, synthetic materials have become popular due to cost and weight advantages – the rolls are longer, lighter and faster to install. Some of these newer materials have textured surfaces making them easier to walk during shingle installation. They can be very durable and can last many years. The exterior covering is where multiple options come into play, each with their own advantages and disadvantages. Here are several of the most common:
Asphalt shingles – this is probably the most common roof covering in use today. They were originally of the three-tab style, but “architectural style” are more commonly installed these days. Asphalt shingles are durable and can be expected to last 20-30 years, if properly maintained. The surface is covered with small, granular material which can retain some dirt (i.e., stains) or even support fungal growth, so some periodic cleaning many be required (usually on roof surfaces under trees on north exposures).
Metal panels – another very popular material, particularly in high wind regions where the large metal panels are less susceptible to wind damage. Metal panels are fastened to the structure with a series of clips, anchors or gasketed screws. The most common metal panel designs are standing seam and corrugated panels. Standing seam is a more expensive option due to installation which includes concealed fasteners, but generally will last longer – potentially upwards of 50 years. Corrugated panels are fastened through the face of the material with gasketed screws to prevent water intrusion. The metal can last 25-50 years, but the gaskets on the screws typically will not. This means that at some point someone will have to get on the roof to replace the gasketed screws.
Slate and Terra Cotta Tiles – although completely different materials, we are discussing them together due to many similarities. Slate is a natural material (although synthetic slate is also available) which terra cotta is a man-made clay product. Both are extremely long lasting, potentially lasting 50-75 years or longer. They are both heavy and difficult to install, and even more difficult to repair if required, since they can be easily broken if walked upon for maintenance. It is not unusual for slate or terra cotta tile roofs to be disassembled to facilitate replacement of the underlayment, since they can easily outlive the life expectancy of the underlayment.
Like so many aspects of home ownership you really get what you pay for. Asphalt shingles are generally the least expensive option, while slate is the most expensive. And all of these materials have their own specific installation requirements which can substantially affect the longevity of the roof covering material.