Slate roof lifespan, and what shortens it

Slate is one of the most durable roofing materials available, and the lifespan it's known for isn't marketing, it's simply how long slate roofs from a century ago are still doing their job on houses across the country. That longevity comes with trade-offs worth understanding before assuming a slate roof needs replacing just because it's old.

How many years should a slate roof last?

80 to 100 years under normal conditions is the typical figure, and well-maintained slate roofs can go beyond that. This compares to 40 to 60 years for concrete tile and 60 years plus for clay pantile, see our new roof cost guide for the full comparison of material lifespans. The slate itself is a naturally very durable stone, and in most cases it's not the slate that eventually fails first.

What is a major disadvantage of a slate roof?

The fixings, not the slate. Slates are held on with nails, and over many decades those nails corrode. Once a fixing nail fails, the slate above it can slip or come loose entirely, even though the slate itself is still perfectly sound. This is known in the trade as "nail sickness," and it's the main reason older slate roofs eventually need attention, not because the slate has worn out. The other real disadvantage is cost. Slate costs more to buy than concrete tile, and because each slate is fixed and handled individually rather than laid in large sheets, it takes longer to install, which adds to the labour cost of both new roofs and repairs.

How do I know if my slate roof needs replacing?

Not every issue on an old slate roof means the whole roof needs replacing.

• Individual slipped or missing slates, especially scattered across the roof, usually points to nail sickness rather than a problem with the slate itself, and is repairable. See our missing or slipped tiles guide
• Widespread slippage across most of the roof, rather than a handful of isolated slates, suggests the fixings generally are reaching the end of their life, and a full re-roof, reusing any slates still in sound condition, becomes the more practical option
• Cracked or delaminating slates, where the stone itself is genuinely failing rather than just its fixing, are less common but do occur, particularly with some lower quality slate used in past decades
• Sagging beneath the slate covering points to a timber problem rather than the slate

Is natural slate more expensive to repair than concrete tile?

Generally yes, for two reasons. Matching slate has to be sourced in the right size, thickness and colour to sit properly alongside the existing roof, which takes more care than picking a standard concrete tile off a pallet, and each slate is fixed individually with more careful handling than tiles laid in a repeating pattern. It's a fair trade-off against a lifespan that's roughly double that of concrete tile.

Maintaining a slate roof

Slate roofs benefit from periodic checks, particularly on older properties where nail sickness is progressing but not yet obvious from the ground. Catching a handful of slipped slates and re-fixing them promptly is far cheaper than waiting until enough have gone that water has started getting into the timbers beneath. Keeping valleys and gutters clear also matters more on a slate roof than some others, since debris held against slate edges can accelerate the wear on individual pieces.

Working on slate roofs

Slate needs different handling to concrete or clay tile, both to avoid damaging sound slates during other work and because matching an existing roof's appearance takes a trained eye for size and colour. Our slate and tiled roofing service covers repairs, re-fixing and full re-roofs on slate specifically, and every job carries our 10 year written workmanship guarantee. We cover Wisbech, King's Lynn, Peterborough and Norwich, many of which have a good number of original slate roofs still in place.