How long does a slate roof last?
Quality natural slate is one of the longest-lasting roof coverings and can remain serviceable for many decades or over a century in favourable conditions. On older slate roofs, fixings and supporting components may deteriorate before the slate itself.
Slate outlasts its fixings
Natural slate is a durable covering, and on many older properties the slates themselves are still serviceable long after the nails holding them have corroded — the failure mode known as nail sickness.
The symptom is slates slipping across the roof without obvious damage to the slates themselves. Repeatedly re-fixing individual slipped units on such a roof is usually a losing battle.
Assessing a slate roof
Delamination, flaking edges and slates that sound dull rather than sharp when tapped indicate the material itself is deteriorating. Widespread slipping with sound slates indicates fixings.
The distinction matters because one points towards replacement of the covering and the other towards a strip and re-lay, potentially reusing much of the slate.