Slate roofs have a lot going for them in terms of longevity, durability, and classic beauty and style. Much of it is well known, some of it is not so well known.
Yes, natural slate is among the most costly and alluring roofing options for homes, but it is certainly not intended for every roof structure or house.
The high price of slate is perhaps one of its most significant drawbacks. In extreme cases, it may cost about the same to cover a one square area of the roof (100 sq. ft.) with high-end natural slate tiles, as it does to cover a small roof, say 1,000 sq. ft. (or 10 squares), with asphalt shingles. Yet, going strictly by price alone would be an entirely unfair comparison between the two drastically different roofing materials. Slate holds significantly more value than asphalt shingles.
That said, you can expect to pay between $15.00 and $25.00 per square foot to install slate tiles on a typical single-family house. Most homes with slate roofs are larger than an average-sized home. Assuming a roof size of 25 squares or 2,500 square feet, you can expect a total average price range of $37,500 to $62,500 to install a new slate roof on a suitable house with reinforced roof frame (to support the weight of a slate roof).
For most roof types, a professional roofing contractor is your best bet for getting that quality installation, but with natural slate tiles, it is best to go with a slater or a slate roofing specialist.
While a non-specialist or a typical roofer may at first feel confident about their ability to install it, they would often be wrong.
But, if you are really tempted to cut labor costs and go this route, be sure to ask them about their experience and for references or examples of their previous slate roof installations.
As this page on Roofing Calc points out, a poorly installed slate roof is a like not having a roof at all.