Signs you can see from outside
1. Rust that has gone through
On steel roofs, look for rust holes, flaking at the laps between sheets and rust along the gutter line. Surface rust can be treated; rust-through cannot be painted away.
2. Porous, crumbling or broken tiles
Concrete tiles whose surface has worn away absorb water, grow heavy moss and lichen, and crack easily. If many tiles are broken or replacement tiles keep cracking, the roof is near the end.
3. Sagging lines
A ridge or roof plane that dips suggests battens or framing have weakened, often from long-term moisture. This needs inspection.
4. Ridge capping falling apart
Cracked, missing or loose mortar along ridges and hips is common and repairable. But if it is combined with other signs, the whole roof may be due.
5. Corroded flashings and valleys
Rusted valley irons and flashings with holes let water in at the points designed to keep it out. Widespread corrosion suggests the roof system is ageing.
6. Fibro or corrugated asbestos cement
Roofs made of these materials on older coast houses and sheds are old by definition. If they are weathered, cracked or broken, have them assessed and do not disturb them yourself. See asbestos roof replacement and removal.
Signs inside the house
7. Leaks in more than one place
Water stains on ceilings in different rooms, especially if new ones appear each wet season, indicate a roof failing in multiple areas rather than one fault.
8. Daylight in the roof space
If you can see daylight between tiles or around sheets from inside the roof space, wind-driven rain can get in too.
9. Damp, mould and musty smells
Persistent mould on rafters or the ceiling, damp insulation and musty smells suggest ongoing moisture, either from leaks or condensation. See mould and moisture under roofs.
10. Torn or missing sarking
Old foil sarking that is torn, sagging or missing leaves the roof without its backup layer. It can only be properly replaced with the roof off.
11. Rotten battens or timber
Darkened, soft or crumbling timber in the roof space shows long-term moisture.
Signs from history
12. Repeated repairs and storm damage
If you have paid for repairs every year or two and leaks keep coming back, or a storm has caused widespread damage, replacement may be more economical over time. See storm damage roof replacement and leaking roof? when repairs aren't enough.
Age as context, not a rule
A roof's age gives context. Many original concrete tile roofs on coast houses from the 1970s and 1980s are now at the stage where several of these signs appear. But age alone does not decide it. See how often should a roof be replaced.
Weighing several signs together
It helps to sort what you have found into three groups.
Minor and isolated: one leak, a few cracked tiles, a lifted ridge cap, some surface rust on screws. These almost always point to repairs.
Moderate and spreading: leaks in two or three places, rust developing at several laps, cracked pointing along most ridges, patches of mould in the roof space. These suggest the roof is ageing and repairs may be buying limited time; start budgeting.
Major and systemic: rust-through across sheets, tiles breaking underfoot, sagging lines, rotten battens, no sarking under a leaking tile roof, or a cracked asbestos cement roof. These usually mean replacement.
If most of what you have noticed falls in the third group, ask for replacement quotes. If it is mostly the first group, repairs are the sensible first step.
What to do next
- Note the signs you have found, with photos.
- Book an inspection by a roofer who will get on the roof and into the roof space.
- Ask for photos and an explanation of whether repair, restoration or replacement fits.
- If replacement is recommended, get itemised quotes and use our roof replacement checklist.
For budgeting, the cost guide has 2026 ranges, and roof replacement vs roof restoration helps if you are weighing the options.
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.