Not every roof problem needs a full replacement — many issues can be resolved with a targeted repair that costs a fraction of the price. But there are situations where patching things up is throwing good money after bad. Knowing the difference can save you thousands.
Here are seven signs that your roof is beyond repair, along with the action you should take for each.
1. Your Roof Is Over 80 Years Old With Original Fixings
Natural slate lasts 75 to 100+ years, but the fixings don't. If your Devon or Cornwall property still has its original iron nails from the Victorian or Edwardian era, they're likely corroding — a condition called nail sickness. Once nail sickness takes hold, slates slip throughout the roof rather than in isolated spots.
A full re-slate with stainless steel fixings solves this permanently. Individual slate repairs on a roof with nail sickness are a temporary measure — more slates will continue to slip.
2. Multiple Leaks in Different Locations
A single leak — say, around a chimney or in a valley — usually points to a specific failure in the leadwork or a localised issue. That's a repair.
But if you're getting leaks in multiple locations across the roof, it suggests widespread failure of the covering, the felt underneath, or both. At this point, the cost of chasing and fixing individual leaks will eventually exceed the cost of a new roof, and you'll still have a deteriorating structure above your head in the meantime.
3. Daylight Visible Through the Roof Boards
Go into your loft on a sunny day and look up. If you can see pinpoints of daylight through the roof boarding, it means slates or tiles have slipped, cracked, or are missing — and the felt beneath has deteriorated or doesn't exist on older properties.
A handful of light spots might be repairable. But if daylight is visible across a wide area, the underlayment has failed and a re-roof is needed.
4. Sagging or Uneven Roofline
Stand across the street and look at your roofline. It should be straight. A visible dip, sag, or wave in the ridge or slope indicates structural problems — rotten rafters, failed purlins, or excessive weight from waterlogged materials.
This is serious. A sagging roof isn't just a covering problem — it's a structural one that needs addressing before it gets worse. A professional inspection will determine the extent of the damage and whether the timbers can be repaired or need replacing as part of a full re-roof.
5. Widespread Moss Growth Lifting Tiles
Moss is common on Devon and Cornwall roofs thanks to our damp climate. Light surface moss is cosmetic and can be addressed with professional roof cleaning.
However, if moss has been left untreated for years and is now thick enough to physically lift tiles or grow between slate courses, it may have caused significant damage underneath — trapping moisture against the tiles, blocking drainage, and accelerating deterioration. If a roof clean reveals crumbling tiles, perished felt, or rotten battens beneath, replacement is more cost-effective than repair.
6. Your Energy Bills Have Increased Significantly
A failing roof often means failing insulation. As the covering deteriorates and allows moisture in, loft insulation becomes damp and loses its effectiveness. You might notice rooms below the roof feeling colder, or your heating bills climbing year on year without explanation.
A re-roof is an opportunity to bring insulation up to current building regulation standards, which can significantly reduce your ongoing energy costs and improve comfort throughout the house.
7. You're Planning Major Home Improvements
If you're investing in a loft conversion, extension, or solar panel installation, it makes practical and financial sense to address the roof at the same time. Installing solar panels on a roof that will need replacing in 5–10 years means paying for panel removal, roof work, and panel refit — effectively tripling the disruption and significantly increasing the total cost.
Combining a re-roof with other work means one scaffolding hire, one project team, and everything done together. It's the most cost-effective approach for major property improvements.
When Repair Is Still the Right Call
To be clear, many roof problems are genuine repair jobs. Here's when a repair makes sense:
- Isolated slate or tile damage: A few cracked, slipped, or missing slates from a storm.
- Localised flashing failure: Lead around a chimney or dormer that's cracked or lifted.
- Blocked or damaged gutters: Gutter issues often get mistaken for roof leaks.
- Single area of felt failure: If the covering is sound but the felt has perished in one section.
- Chimney repointing: A deteriorating chimney stack doesn't mean the whole roof needs replacing.
What to Do Next
If you've noticed any of the seven signs above, the first step is a professional inspection. We provide free roof inspections across Devon and Cornwall with no call-out fee. We'll photograph any issues, explain the options — repair or replacement — and give you a clear, honest quote so you can make an informed decision.