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When to repair vs replace your roof
The cheapest roof is almost always the one you already have. But there's a point where targeted repair becomes false economy — when the underlying material has aged out and you're patching ahead of the next failure. Here's how Australian roofers usually frame the call.
The age threshold
If the roof is at or past the typical lifespan for its material (Colorbond 30–50 years, concrete tile 30–50, terracotta 50+, slate 100+), and you're seeing more than one issue, replacement is usually the better economic choice. Repairing one of three failure points just delays the next call-out.
The 20% rule
A common roofer rule of thumb: if more than 20% of the roof material is damaged, broken, or weathered, replace rather than repair. Below 20%, targeted repairs are usually the right call. Above 30%, repairing is throwing money at a roof that's structurally close to needing replacement anyway.
Secondary damage
If the leak has been active long enough to affect ceiling plaster, insulation, ceiling joists, or wall framing, the repair scope expands quickly. Fixing the roof without addressing the secondary damage just locks moisture into the structure. At that point a roofer plus a builder needs to look at the job together — and full replacement often costs less than the combined patch + secondary remediation.
The signals that mean "replace"
- Multiple active leaks in different parts of the roof
- Visible sag or dip in the roof line from outside
- Granules in the gutters every clean (asphalt-shingle deterioration; rare in Australia but seen on imported designs)
- Ridge-cap bedding and pointing has failed in three or more locations
- Sarking is degraded or absent and you're seeing condensation in the ceiling cavity
- The current material is no longer manufactured (you can't colour-match repairs)
Get two quotes
For any job over $5,000, get at least two quotes — and compare the scope, not just the headline number. One roofer's "$8,000 repair" and another's "$15,000 replacement" might be quoting completely different jobs. Ask each what's included, what's excluded, what the workmanship and materials warranty terms are, and whether a council permit is required.
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