The question we're asked most often at the survey stage isn't “how much will it cost?” — it's “do I really need a full replacement, or can it be repaired?” The honest answer is that it depends on the roof, and the only way to know for certain is a proper inspection. But there are indicators that point strongly in one direction or the other.
Signs That Point Toward Repair
A Small Number of Slipped or Missing Tiles
One to five displaced tiles in a localised area — particularly after a storm — is almost always a repair. We replace the tiles, check the surrounding area for nail failure or batten damage, and the job is done. On Maidstone's Victorian clay tile stock, individual tile replacement is common maintenance and doesn't indicate wider failure.
A Localised Leak
A single leak tracing back to a failed lead flashing at a chimney or dormer, a cracked valley lining, or a broken tile over the affected area is repairable. Lead work failures on Maidstone's period properties are very common and almost always fixable without a full re-roof. See our lead work page for more detail.
Ridge or Hip Mortar Failure
Loose or missing bedding mortar on ridge and hip tiles is a repair category. We repoint the affected sections using a semi-flexible mortar mix. This is especially common on exposed properties in Lenham and the North Downs area, and on post-war semis across Coxheath and Paddock Wood.
Signs That Point Toward Replacement
Widespread Nail Sickness
On Maidstone's Victorian and Edwardian Welsh slate and clay tile roofs, nail sickness — where the original iron nails corrode and lose their grip — is the most significant failure mode. When it affects more than 15–20% of the roof, individual repairs become ineffective because tiles continue to slip unpredictably across the whole surface. A re-roof is the only lasting solution. The tell-tale signs are multiple slipped tiles in different areas of the roof, tiles rattling in wind, and tiles found in the garden with no obvious mechanical cause.
Concrete Tile Delamination Across 20%+ of the Roof
The 1960s and 70s concrete interlocking tile estates in Penenden Heath, Park Wood, Coxheath and Larkfield are now at the age where widespread delamination — surface aggregate loss and laminar splitting — affects the majority of tiles on many roofs. Once this has spread beyond roughly a fifth of the roof area, patching becomes more expensive than replacing over the next 3–5 years. We'll tell you honestly where the threshold is on your specific roof.
Failed Felt Visible from the Loft
The felt (or breathable membrane) under the tiles is the last line of defence against water ingress if tiles are displaced. On roofs from the 1950s through to the mid-1990s, original bitumen felt is now beyond its service life — it becomes brittle, tears, and in many cases has already failed. If you look into your loft and can see daylight through the felt, or find it torn and hanging, the underlay needs replacing. This almost always means a full strip and re-roof is more cost-effective than trying to patch the membrane from below.
Recurring Leaks Despite Multiple Repairs
If you've had the same area repaired two or three times and water continues to get in, the underlying roof structure is the problem rather than individual tiles or flashings. This is a clear signal that a more comprehensive solution is needed.
The 80-Year Rule for Clay Tile and Slate
Clay plain tile roofs and Welsh slate roofs laid before the 1950s are now 70–80+ years old. The tiles themselves may still be sound — good clay tile lasts indefinitely — but the battens, nails and felt beneath them will typically be at or past end of life. If you're on a pre-war Maidstone property and haven't had the roof stripped and re-laid in living memory, it's worth a professional inspection to assess the state of the substructure.
What to Do Next
The only reliable way to distinguish repair from replacement is an inspection from ground level plus a loft inspection. We carry out free surveys across Maidstone and the surrounding area. Call 0162 229 6232 and we'll arrange a visit at a time that suits you. You'll get an honest recommendation — if repairs are the right call, we'll quote for those. If replacement makes more sense long-term, we'll explain exactly why and what it involves.
You can also read our full guide on roof replacement costs in Maidstone for price context before your survey.