Cracked tiles & ridge capping, explained

Most tile roofs around Geelong are either concrete or terracotta. Both are durable and can last for decades, but neither is immune to the two things that age a roof: movement and weather. Understanding how each tile type behaves helps explain why leaks appear where they do.

Concrete vs terracotta tiles

Terracotta tiles are fired clay — hard, colour-stable and long-lived, but brittle, so they chip and crack under impact or footfall. Concrete tiles are tough and economical, but their surface coating weathers over time, and they can absorb more moisture as they age. In both cases, the failure point is usually the same: a crack that lets water through.

Why micro-cracks matter

In older suburbs like Geelong West and Belmont, shifting soils and decades of thermal movement — tiles heating in the sun and cooling overnight, again and again — cause fine hairline fractures. These micro-cracks are almost invisible from the ground, but each one is a doorway for water. During wind-driven rain, water is pushed into the crack, soaks through, and tracks down to the ceiling below.

A single cracked tile rarely looks dramatic. The damage it causes inside, left long enough, often does.

Tiles also "slip" — creep out of position — when the clips or mortar holding them weaken. A slipped tile breaks the overlap that keeps the roof watertight, and the gap it leaves does the rest.

The ridge line: where capping comes in

Run your eye along the very top of the roof and the angled hips, and you'll see the ridge capping — the rounded tiles that cover the join where two roof planes meet. These caps are traditionally held down with mortar, and that mortar is one of the hardest-working, most exposed parts of the whole roof.

Over years of heat, cold and movement, old sand-and-cement mortar cracks, shrinks and lifts. Once it does, wind-driven rain gets underneath the caps and straight into the roof space. Loose caps are also a safety issue in high wind.

Re-bedding vs re-pointing — what's the difference?

These two terms get used interchangeably, but they're different jobs:

• Re-bedding means lifting the ridge caps and laying a fresh bed of mortar underneath to re-seat them properly. It's the bigger job, needed when the original bedding has failed.
• Re-pointing means renewing the visible pointing layer over the bedding — the strip that seals and finishes the join. It's done when the bedding is still sound but the pointing has cracked.

Modern repairs increasingly use a flexible pointing compound rather than rigid sand-and-cement. The reason is movement: a flexible polymer pointing flexes with the roof as it expands and contracts, instead of cracking the way traditional mortar does. That's why a re-point done with the right material tends to last far longer.

Spot repair or whole-of-ridge?

If only a few caps have let go, a targeted repair may be enough. If the pointing is cracked along the entire ridge, doing the lot at once is usually better value than returning for repeated patches — and it resets the clock on that part of the roof. A proper consultation is what tells you which situation you're in.