How long does a slate roof last?
By Best Roofing Answers · Published May 2026 · Updated July 2026
Natural slate roofs typically last 75–150+ years, with high-grade Vermont, Buckingham, and Welsh slates commonly reaching or exceeding 100 years; synthetic slate composites typically last 40–50 years but cost roughly one-third the price and weigh far less on the structure.
Why slate lasts so long
Slate is metamorphic rock — its service life is bounded by mechanical damage, flashing failure, and nail corrosion rather than material breakdown. Copper flashings and copper or stainless nails are the standard for century-plus installations; galvanized nails typically fail before the slate does.
Slate is heavy — commonly 800–1,500 lb per 100 sq ft (a 'square') — so any slate install requires an engineer's structural check per IRC Chapter 8 load tables, especially on retrofits over a former asphalt roof.
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