1. Summer storms
Most of the coast's heavy weather arrives in the warmer months. Storm cells bring strong gusts, intense rain and sometimes hail. The combination tests every weak point at once.
- Wind uplift lifts poorly fixed sheets, tiles and ridge caps.
- Wind-driven rain is pushed sideways and uphill under tiles and flashings.
- Hail can crack brittle tiles and dent steel; see hail-damaged roof.
- Falling branches break tiles, puncture sheets and crush gutters.
2. Heavy rainfall
Short, intense downpours can overwhelm gutters, valleys and downpipes. Water backs up and overflows into the eaves or roof space. Undersized or blocked gutters, and box gutters without adequate overflows, are frequent culprits.
3. Salt
Within reach of onshore breezes, salt accelerates corrosion of steel sheets, fixings, flashings and gutters, especially in areas not washed by rain. See coastal roof materials.
4. Humidity and condensation
Warm, moist air condenses on cool surfaces in the roof space, especially under steel without a blanket. The result is rust from the inside, damp insulation, rotting battens and mould. See mould and moisture under roofs.
5. Moss, lichen and organic growth
Humid, shaded roofs grow moss and lichen, particularly on concrete tiles. Growth holds moisture against the tiles, blocks water paths and can lift tiles slightly.
6. UV and heat
Strong sun breaks down sealants, plastic components and paint finishes, and expands and contracts materials daily. Ridge pointing cracks, flashings lose their seal and finishes fade.
7. Blocked gutters and valleys
Leaves, palm fronds, sand and debris build up in gutters and valleys, holding water against metal and causing overflows into the house during rain.
8. Foot traffic and other trades
Tiles crack when walked on, particularly older concrete tiles. Aerials, air-conditioning units, solar panels and satellite dishes each add fixings and penetrations that can leak if not properly flashed.
9. Poor installation
Wrong fixings for the exposure, inadequate tie-downs, missing sarking, silicone instead of flashings, swarf left on steel and incompatible metals all cause problems that may take years to appear.
10. Age
Every roof eventually wears. Concrete tile surfaces erode, mortar cracks, coatings weather and fixings corrode. Age turns small problems into larger ones. See how often should a roof be replaced.
11. Pests
Possums, rats and birds can lift tiles, damage sarking and nest in roof spaces, and termites can damage timber framing. Signs include droppings, noise and damaged insulation.
Reducing the risk
- Clear gutters and valleys before and during the wet season.
- Trim overhanging branches.
- Fix loose tiles, ridge caps and fixings promptly.
- Ask other trades to protect the roof and flash any penetrations properly.
- Wash salt from sheltered areas on steel roofs near the sea.
- Check the roof space for moisture once a year.
- When re-roofing, choose materials and details suited to the site.
When damage becomes replacement
If several causes have combined over many years, the roof may be failing as a system. See signs you need a roof replacement and storm damage roof replacement.
How the causes combine
Roof damage rarely has a single cause. A typical sequence on the coast looks like this: leaves build up in a valley over winter; the valley iron stays damp and starts to rust; the first heavy storm of summer overflows the blocked valley and pushes water under the neighbouring tiles; the sarking, already brittle from age, lets that water reach the ceiling; and the owner sees a stain in the hallway. Each of those factors is minor alone. Together they produce a leak, damp insulation and possibly rotting battens.
The same pattern plays out on steel roofs near the beach, where salt sits on a sheltered section under the eaves, the fixings corrode, a gust in a storm cell loosens a sheet and rain gets in at the lap. Understanding how causes stack up is why a good roofer looks at the whole roof and the roof space, not just the spot above the stain, and why regular, low-cost maintenance prevents so many expensive repairs.
Getting help
For any of these issues, book an inspection through roof repairs. A roofer will identify the cause and recommend the right fix.
General information for Sunshine Coast property owners, not advice about your particular roof. Rules, products and programs change; confirm with the authority named, or with Sunshine Coast Council or Noosa Shire Council, before acting.