Signs You Need a New Roof, Not Just Repairs
The five signs you need a new roof are: widespread nail sickness across multiple slopes, multiple simultaneous leaks, extensive tile deterioration, sagging roof lines, and repair costs consistently exceeding £600–£800 per year. A free survey confirms whether repair or replacement is more cost-effective.
The decision between continuing to repair a Chichester roof and replacing it altogether is one of the most consequential — and most commonly deferred — decisions homeowners face. Deferred too long and the roof generates escalating emergency costs and the risk of water damage to the property. Made too early and money is spent unnecessarily. This guide gives you the clear indicators that replacement is the right call, based on 22 years of making this assessment on Chichester properties.
The Repair Treadmill: When to Recognise It
The most reliable indicator that a Chichester roof has crossed from repair territory into replacement territory is what we call the repair treadmill — the pattern where each repair addresses an individual failure while the underlying condition continues to deteriorate, generating the next failure on a different slope or a different element.
The typical repair treadmill on a post-war Chichester property looks like this: a few tiles come off in the October gales and are replaced (£150 to £300). Six months later, tiles come off a different pitch in the January storm (£200 to £400). A ridge tile lifts and is reseated (£100 to £200). The following autumn, another pitch loses tiles (£250 to £450). By this point, £700 to £1,350 has been spent in 18 months and the roof is fundamentally in the same condition it was at the start — because the underlying cause is nail sickness, not the specific tiles that came off.
When you recognise this pattern, the comparison to make is not "repair cost this time" versus "replacement cost." It is "total repair spend over the next 5 years" versus "replacement cost now." On a nail-sick Chichester post-war roof, the 5-year repair spend on a treadmill typically exceeds the replacement cost.
When more than 15 to 20 per cent of tiles show movement or deterioration, replacement typically becomes more cost-effective than continued repair.
— own field data across Chichester roofing surveys, 2024
The Seven Signs That Replacement Is the Right Call
1. Nail Sickness Across Multiple Pitches
A single nail-sick tile that has slipped can be re-fixed. Nail sickness affecting two or more pitches means the fixing system of the entire roof has reached the end of its life. Re-fixing individual tiles on a nail-sick roof is the definition of the repair treadmill — each fixed tile is surrounded by tiles that will slip in the next event.
2. More Than 30 to 40 Per Cent of the Tile Area Compromised
When a substantial proportion of the tile area is either cracked, slipped, damaged or otherwise deficient, targeted repair becomes impractical. The labour cost of addressing each affected tile individually approaches or exceeds the labour cost of a full strip and relay. At this threshold, replacement delivers a new covering at a similar or lower total cost than repair, and with the added benefits of new felt or membrane, new battens and a properly fixed ridge.
3. Felt Underlay Deterioration
The bituminous felt underlay under the tiles is the secondary weather barrier — the last line of defence if a tile fails or a ridge joint opens. It cannot be replaced without stripping the entire tile covering. When a survey inspection reveals felt that is brittle, torn or showing light through it, the secondary barrier has failed. A roof without an intact secondary barrier is relying entirely on its tiles for weather protection. Once the felt has reached this condition, the case for a full re-roof that replaces both tiles and membrane is compelling.
4. Ridge Mortar Failure Across the Full Run
Open ridge mortar that has failed along the entire ridge run — rather than at isolated points — indicates that the whole roof has reached the end of the mortar bedding's service life. Re-bedding the entire ridge is a significant job in its own right. When it is combined with tile condition that is also reaching end of life, the case for addressing everything together in a replacement rather than separately in sequential repairs is straightforward.
5. Structural Timber Deterioration
A sagging roof line or visible deflection in the roof plane indicates structural timber movement — typically rafter or ridge board deterioration. This cannot be addressed from outside the roof covering. A full re-roof provides the opportunity to inspect and replace deteriorated structural timber that would not be accessible any other way. If structural deterioration is suspected from ground-level inspection, a professional survey is needed urgently.
6. Cumulative Annual Repair Spend Above £600 to £800
When the annual maintenance and repair spend on a roof has been consistently above £600 to £800 for two or more years, the replacement calculation becomes compelling. A re-roof at £6,000 to £9,000 on a Chichester post-war semi, amortised over 40 years, costs £150 to £225 per year. If the roof is already costing £800 per year in repairs, replacement is already cheaper on an annual basis — before accounting for the emergency risk.
7. The Property Is Being Sold
A roof survey is one of the checks that Chichester buyers increasingly commission before exchange. A failing roof — visibly nail-sick, with an aging felt and open ridges — will either trigger a price reduction negotiation or kill the sale entirely. A replaced roof removes this concern, typically adds more value than the replacement cost to the sale price in the Chichester market, and allows the sale to proceed on its merits rather than becoming a roof negotiation.