Slate roof tiles are usually fixed with copper nails, or with hooks as is common with Spanish slate. In the UK, fixing is typically with double nails onto timber battens (England and Wales) or nailed directly to timber boards (Scotland and Northern Ireland). Nails are traditionally of copper, although there are modern alloy and stainless steel alternatives. Both these methods, if used properly, provide a long-lasting weather tight roof with a lifespan of around 80–100 years.