Slate roofs are very durable and the most fire retardant roofing material. Although very beautiful, they are very heavy. It is important that the trusses and wood support is in proper shape to support the weight. It is also very important that only a person skilled on slate walk on these roofs. If they are not handled with care, they can be susceptible to cracks.
Slate is one of the most expensive roofing materials other than copper.