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 to for every roof structure.
The high price of slate is perhaps one of its most significant drawbacks. It may cost about the same to cover a roof square (100 sq. ft.) with high-end natural slate, 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. Slate holds significantly more value than Asphalt shingles.
Cost of Materials
On the low end, the cost of natural slate material alone is about $4.50 per sq. ft. While that makes it sound almost affordable, keep in mind that asphalt shingles, on the low end cost less than $1.00 per sq. ft. of material (based on buying 3-tab or mid-range architectural shingles by the bundle).
On the high end, the cost of slate tiles can be as high as $10.00 to $15.00 per sq. ft. for materials only.
Pro Tip: A fair price range for natural slate tile materials designed for residential applications is between $4.50 and $8.50 per sq. ft.
Installation Cost Per Sq. Ft.
Installation costs vary, though it is fair to double the price within the material prices range from above. Such that it would be $12 to $18 per sq. ft. of slate roofing installed.
For most roof types, a professional roofing contractor is your best bet for getting that quality installation, but with slate, 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.