Every roof has a finite lifespan — and knowing when yours has crossed the line from "needs a repair" to "needs replacing" can save you thousands of pounds in water damage, structural decay, and wasted repair bills. The trouble is, most homeowners only think about their roof when water starts coming through the ceiling. By that point, you're often dealing with far more than a simple tile replacement.
This guide walks you through the seven warning signs that indicate a full roof replacement is likely needed — not just a patch-up — and explains how to make an informed decision about what to do next.
Sign 1: Your Roof Is Past Its Expected Lifespan
Different roofing materials have very different lifespans, and the age of your roof is the single biggest factor in determining whether it needs replacing. Here's what you should expect in the UK climate:
- Natural Welsh slate: 80–150 years. Many Victorian and Edwardian properties in the UK still have their original slate roofs in serviceable condition.
- Concrete tiles (Marley, Redland): 30–50 years. These are the most common roofing material on post-war UK homes. If your house was built in the 1970s or 1980s, your concrete tiles are now approaching the end of their useful life.
- Clay tiles: 60–100 years. More durable than concrete, but the battens and felt beneath them often fail first.
- Flat roof felt: 10–15 years. If your garage or extension has an old felt flat roof, it's almost certainly overdue for replacement.
How to find out your roof's age: If you don't know when the roof was last replaced, check your property's title deeds, ask previous owners, or look at planning applications on your local council's website. A qualified roofer can also estimate the age based on tile type and the condition of the underlay.
Sign 2: Missing, Cracked, or Curling Tiles
A few missing or cracked tiles after a storm is normal — and a straightforward repair costing £150–£300. The concern is when tile damage is widespread or recurring. Signs of systemic failure include:
- Multiple tiles missing from different areas of the roof (not just one exposed section)
- Tiles that have become brittle and snap when handled — this indicates frost damage has worked through the tile material over many freeze-thaw cycles
- Curling or lifting tiles that no longer sit flat, which means the nibs (the hooks that hold tiles to the battens) have broken or the battens beneath have rotted
- Tiles that are "spalling" — the surface layer flaking away, exposing the porous core to water absorption
When the damage is localised (one corner, one row), a repair makes sense. When tiles are failing across the whole roof, you're dealing with a material that has reached the end of its life. Replacing individual tiles on a failing roof is like putting new tyres on a car with a blown engine — it doesn't solve the underlying problem.
Sign 3: Daylight Visible Through the Roof Boards
This is one of the easiest checks any homeowner can do. Go into your loft on a bright day, turn off the light, and look up at the underside of the roof. If you can see pinpricks of daylight coming through, it means there are gaps where rain can — and will — penetrate.
What to look for:
- Points of light between tiles or slates (indicating shifted or missing tiles)
- Light showing through the felt underlay itself (the felt has perished)
- Evidence of water staining on the timber around these light points
In older properties (pre-1970s), roofs were often laid without any felt underlay — tiles were simply hung on battens with no secondary barrier. These roofs can function for decades, but once the tiles start to slip or crack, there's nothing else keeping the water out. If your roof has no felt underlay and tiles are deteriorating, replacement with a modern breathable membrane is strongly recommended.
Sign 4: A Sagging Roof Deck
A roof that visibly sags or dips when viewed from the street is a serious structural concern. This isn't a cosmetic issue — it indicates one or more of the following problems:
- Rotten rafters: The main structural timbers have decayed due to prolonged moisture exposure, often caused by a failing roof covering that has been leaking undetected for years.
- Failed battens: The horizontal timbers that tiles are fixed to have rotted. When battens fail, tiles can slide and the load distribution across the roof changes.
- Overloaded structure: Sometimes a previous reroofing job used heavier materials than the original structure was designed for — for example, replacing lightweight slates with heavy concrete tiles without reinforcing the timbers.
- Inadequate original construction: Particularly common in 1960s and 1970s housing where timber sizes were sometimes insufficient for the span.
A sagging roof requires urgent professional assessment. If caught early, it may be possible to reinforce the timbers and replace the covering. Left too long, you may need a complete structural rebuild of the roof — a significantly more expensive project.
Sign 5: Granule Loss in Your Gutters
This sign is specific to mineral-surfaced felt roofs and some types of composite tile. When you clean your gutters, look at what's accumulated. A small amount of fine grit is normal — it washes off over time. But if you're finding significant amounts of coarse granules — the coloured stone chippings that coat the surface of felt roofs and some tiles — your roof covering is breaking down.
The mineral granules on felt roofs serve two purposes: they protect the bitumen from UV degradation, and they provide a degree of fire resistance. Once the granules are gone, the exposed bitumen dries out, cracks, and starts to leak within a few years. There's no practical way to re-coat the granules — the roof covering needs replacing.
On concrete tiles, granule loss manifests as a dusty, faded appearance. The tiles look bare and lighter in colour compared to newer tiles of the same type. This indicates the surface has eroded and the tile is now more porous and prone to frost damage.
Sign 6: Persistent Leaks Despite Repeated Repairs
This is perhaps the most telling sign, and the one most homeowners experience before finally accepting a replacement is needed. The pattern typically looks like this:
- You notice a damp patch on a bedroom ceiling after heavy rain
- A roofer comes out, replaces a few tiles and some flashing — cost: £200–£500
- The leak stops for a few months, then returns — perhaps in a slightly different location
- Another repair. Another bill. Another few months of dry.
- The cycle continues, with each repair costing more and the dry periods getting shorter
What's happening is cumulative failure. The underlying felt or membrane has perished across the entire roof. The battens are deteriorating. The tiles have lost their weather tightness. Fixing one leak simply moves the weakest point to the next area of failure.
A useful rule of thumb: If you've spent more than £1,000–£1,500 on roof repairs in the last 3 years and the problems persist, you'd likely be better off financially putting that money toward a full replacement rather than continuing to patch a failing roof.
Sign 7: Significant Moss and Algae Growth
Some moss on a roof is normal in the UK — our damp climate encourages it. The concern is when moss growth becomes heavy and extensive. Here's why it matters:
- Moss roots penetrate tile surfaces, particularly on older concrete and clay tiles where the surface has already started to erode. This accelerates deterioration and creates channels for water to enter.
- Thick moss holds moisture against the tile surface, keeping it permanently damp. In winter, this trapped moisture freezes and expands, cracking tiles from the inside out (frost damage).
- Moss growth on ridge tiles can force apart the mortar (pointing) that holds them in place, leading to loose ridge tiles that can blow off in storms.
- Moss debris washes into gutters, blocking them and causing water to overflow down external walls — a common cause of penetrating damp inside homes.
Moss can be professionally cleaned and the roof treated to slow regrowth. But on an older roof where the tiles are already compromised, cleaning can actually do more harm than good — pressure washing can dislodge fragile tiles, and the cleaning process often reveals just how deteriorated the roof covering really is.
Repair vs Replace: How to Make the Decision
The repair-or-replace question comes down to three key factors:
1. Condition of the Underlayers
The tiles or slates you see from outside are only part of the roofing system. Underneath, there are battens (timber strips that tiles hook onto) and an underlay (felt or breathable membrane). If the tiles are failing but the battens and underlay are sound, a strip-and-retile might work. If the battens are rotten and the felt has perished — which is common on any roof over 30 years old — you need a full replacement including new battens, new underlay, and new tiles.
2. Cost Comparison
Get a quote for the full replacement, then compare it to what you've been spending (and expect to continue spending) on repairs. A full replacement typically costs £5,000–£15,000 depending on roof size and materials, but it comes with a 20–50 year lifespan. Ongoing repairs of £500–£1,000 per year on an old roof will cost you the same amount over 10–15 years — with no guarantee the problems will stop.
3. Roof Age
If your roof is within the last 20% of its expected lifespan and showing multiple signs of failure, replacement is almost always the better investment.
What Does a Roof Survey Involve?
Most reputable roofing contractors offer free roof surveys, particularly if they're quoting for potential work. A proper roof survey includes:
- External visual inspection from ground level and (where safe) from a ladder — checking tiles, flashing, ridge tiles, valleys, and guttering
- Loft inspection — checking the underside of the tiles, the condition of the felt underlay, timber condition (rafters and battens), signs of water ingress, and ventilation
- Assessment report with findings, photos, and a recommendation on whether repair or replacement is the appropriate course of action
Be wary of any roofer who diagnoses problems from the ground without inspecting the loft space, or who pressures you into an immediate decision. A good roofer will explain what they've found, provide options, and give you time to decide.
Rough Costs for Roof Work in 2025
To help you budget, here are typical UK prices for common roof work in 2025:
- Minor tile repair: £150–£500
- Flashing repair: £200–£500
- Ridge tile repointing: £300–£800
- Section re-roofing: £1,000–£3,000
- Full roof replacement (terraced house): £5,000–£8,000
- Full roof replacement (semi-detached): £6,000–£11,000
- Full roof replacement (detached): £9,000–£18,000
These prices include scaffolding, materials, labour, and waste disposal. Natural slate costs significantly more than concrete tiles. Complex roof shapes with hips, valleys, and dormers add to the cost.
What to Do Next
If you've recognised two or more of these warning signs on your own roof, the next step is to arrange a professional roof survey. Don't ignore the early signs — catching problems before they become structural emergencies is always cheaper and less disruptive.
At Pinnacle Roofing, we provide honest, no-obligation roof assessments. We'll tell you whether your roof can be repaired or whether replacement is the better long-term investment — and we'll explain exactly why.