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Slate roof tiles are usually fixed (fastened) either with nails or with hooks (as is common with Spanish slate).[6] In the UK, fixing is typically with double nails onto timber battens (England and Wales)[7] or nailed directly onto timber sarking boards (Scotland and Northern Ireland).[citation needed] Nails were traditionally of copper, although there are modern alloy and stainless steel alternatives.[8] Both these methods, if used properly, provide a long-lasting weathertight roof with a lifespan of around 60–125 years.[2]