Maintaining an older tiled roof: 5 helpful hints

August 21, 2015

The modular nature of a tiled roof means most repair jobs are quite manageable. The tricky part is working with tiles that are brittle with age. Here are five helpful hints for maintaining an older tiled roof.

Maintaining an older tiled roof: 5 helpful hints

1. Let it be

  • If your tile or slate roof is old, but still sturdy and free of leaks, resist the temptation to fiddle with it.
  • Old tiles and slates become brittle with age and are very easily cracked or broken, so even a simple spring clean can end up causing more problems than it solves.

2. Watch your step (and mind the tiles)

  • Modern terracotta tiles can withstand a small amount of foot traffic, but older tiles can be extremely fragile.
  • If you must walk across a tiled roof, take care to walk on the strongest part, which is the front edge of each tile, where tiles overlap.
  • Wear soft-soled shoes such as running shoes. Do not wear thongs (flip-flops) as they can easily trip you up.

3. Remove the moss, leave the lichen

  • Lichens and mosses grow naturally on tiled roofs, particularly parts that are in permanent shade.
  • Lichen is harmless but moss can trap moisture so it's best removed.
  • To remove moss, wash the tiles with a solution of 2 kilograms (4 pounds) of copper sulphate in 45 litres (11 gallons) of water.
  • This solution can damage gutters and downpipes, so rinse them thoroughly when you're finished.

4. Try some pressure

  • If you'd rather not use copper sulphate to get the lichen and moss off your tiles, consider using a high-pressure water cleaner instead.
  • Work from the top of the roof down, otherwise water will be forced up under the tiles.
  • Walking on a wet roof is dangerous; don't do it unless you're wearing a safety harness.

5. Stop your fretting

  • From time to time it's worth taking a look at the underside of your terracotta tiles to check for "fretting."
  • Fretting is a sort of crumbling that occurs when salt from the atmosphere crystallises under a tile's surface, gradually wearing off the outer layer of the tile.
  • The exposed side of the tile is rarely affected, probably because rain washes off any salt and keeps the tile's surface clean.
  • Fretting is most common near the ocean, but can also occur inland.
  • Badly fretted tiles must be replaced before they crumble completely.

Follow this five helpful hints and your tiled roof repair job will be all the more manageable — even if your tiles are brittle with age.

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