How Long Does A Slate Roof Last?

How Long Does Slate Last?

Good natural slate can last for many decades, and well over a century on some roofs. Welsh slate has a long reputation for durability, and plenty of slate roofs across North Wales have been doing their job for generations.

Man-made (fibre cement or composite) slates generally have a shorter life, and how long they last depends on the product and the quality of the installation. If you are weighing up the two, we can talk you through the trade-offs for your property.

What Usually Fails First

It is rarely the slate itself. On most older slate roofs, the parts that wear out first are:

• The fixings. Old nails corrode over time, and slates start to slip. This is often called nail sickness.
• Lead flashings and valleys. These can crack, split or lift around chimneys, valleys and abutments.
• Ridge and hip details. Mortar and bedding crumble with age and weather.
• The membrane and battens under the slates. On very old roofs these may be rotten or missing.

That is good news, because it means many slate roofs can be repaired and kept going rather than replaced.

Signs A Slate Roof Is Wearing Out

• Slipped or missing slates, often visible from the ground
• Slates that are flaking, crumbling or splitting in layers
• Leaks or damp patches, especially after strong wind and rain
• Daylight visible through the roof from the loft
• A sagging roof line, which can point to a structural problem

Repair Or Replace?

If the slates are generally sound, replacing the damaged ones and renewing the flashings can give an old roof many more years. If the slates themselves are failing across the roof, or the same areas keep slipping, a full re-roof is usually better value than repeated repairs.

We will give you an honest view. See our slating and tiling page, or read how to decide between a repair and a replacement.

Looking After A Slate Roof

• Have it looked at every few years and after severe weather
• Keep gutters clear so water does not back up under the slates
• Do not walk on a slate roof. Slates crack easily and it is dangerous
• Deal with small problems early, before water gets in