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As many architects and contractors know, roofing slate can be specified in natural or man-made fibre-cement - varieties. However, in order to make the right choice for a particular project, you need to have an understanding of the qualities of both, as well as the application for which each is best suited.

Natural slate is a traditional building material, with a heritage that dates back to Roman times. It offers aesthetic appeal and durability. Natural slate can become a major factor in a building’s whole life costs, which is important since environmental issues are moving to the forefront in all areas of construction. A slate roof will last the lifetime of the building, if laid correctly.

The other big plus to natural slate is that it is sustainable, and can be salvaged and re-used. Natural slate, tested to BS EN 12326 Part I and meeting the highest relevant ratings will be unaffected by normal extremes of temperature, and highly resistant to acids, alkalis and other chemicals. Man-made products on the other hand are more liable to discolouration by acid rainfall and the growth of lichens although surface coatings can delay this process.

Natural slate often respects the traditional roofs where it is used and, as a natural product, features variations in colours, sizes and textures. This is important in conservation areas, where slate must match existing roofing materials on surrounding buildings.

Historically, slates were from a local source which means that usually there is a ‘type’ of roofing material particular to a location. However, nowadays with more quarries available, worldwide ‘varieties’ can be suitable, for example, Canadian slate is a great, durable replacement for Welsh slate.

The advances in the production of fibre cement slate now means that a wider range of projects can benefit from a slate roof. Fibre cement slates come in a uniform size, thickness, and shape eliminating the time needed to sort, hole and grade on site, as well as offering added versatility when architects want to use complex roof designs.

Fibre cement tiles are pre-drilled for quick and easy fixing saving time on site. In addition, the slates can be cut and mitred using simple hand tools. This adds to the ease of installation, while the uniformity of the slate also reduces waste. This consistency means it is easier for them to be used on intricate roofs and that they are ideally suited for use by the less experienced roofer.

Budget considerations may lead some to fibre cement slates, since they are generally lower cost than natural slate. Although natural slate may be favoured in conservation areas the improved quality of fibre cement slates means that they can blend well with historic surroundings when natural slate cannot be sourced or is too expensive. In less sensitive areas fibre cement slates can offer the architect versatility on complex designs as well as a huge variation in colours, textures and formats available.

Which then is the right slate for the job? Partly it depends on the style of the building. Contemporary designs often require the sleek consistency of a man-made product. For a period property natural slate is better to look at and complements other traditional building materials and designs.

Natural slate is great to look at, and is extremely tough. That said, it does need to be sorted and worked with and a certain level of expertise to install. Fibre cement options provide a cost-effective and conveniently sized alternative, and their improved quality increased their durability and strength.

Fibre cement slates will require the roofer to be on-site for less time which improves productivity. Modern slates are also resistant to fire, chemicals and fungal growth, and are unaffected by temperature changes as well as being vermin and rot proof. Meanwhile, the low fixed weight of fibre cement slates allows economical use of timber roof trusses.

However, sometimes only the variation in colour and texture of natural slate will do, for example, when it comes to matching the roofing of a particular area or group of buildings. In a nutshell, fibre cement slates offer consistency and convenience, where as natural slate provides the authenticity and character of a natural product.