Repair or Replace
The most expensive roofing mistake is replacing a roof that needed repairing, and the second most expensive is repairing one that needed replacing. Here is how to tell them apart.
The Decision by Maidstone Stock Era
Post-war concrete tile estates
Penenden Heath, Park Wood, Coxheath, Larkfield, Shepway and Senacre were built between roughly 1958 and 1978 with concrete interlocking tiles now at 45 to 65 years against a 30 to 50 year design life.
The useful measure is the proportion of tiles showing exposed aggregate. Under 25 per cent and there are years left, so targeted repair is right. Above 30 per cent and repair frequency climbs steeply because the tiles around each repair are failing too — that is where replacement becomes the cheaper option per year.
Properties on this stock built before 1975 have largely crossed the line already. We still survey each one rather than assuming, because a sheltered north-facing slope can be markedly better than the exposed south-west elevation on the same house.
Key Fact
BRE (Building Research Establishment) service-life data gives concrete interlocking roof tiles an expected life of 30 to 50 years and natural slate or clay tile 60 years and beyond, with fixings and lead flashings frequently reaching end of life before the covering itself on historic roofs.
Victorian and Edwardian stock
Fant, Tovil, Upper Stone Street and the town centre carry clay plain tile and Welsh slate that is 90 to 130 years old. Here the covering usually outlives the fixings, and the question is almost never whether the slate is finished.
Where nail sickness is localised, selective re-nailing in copper reuses the original material and buys 20 to 30 years for a fraction of a re-roof. Where it is widespread across every slope, stripping and re-laying is the answer — but that is still often re-laying the original slate rather than buying new.
The scatter pattern is the diagnostic. Tiles arriving intact rather than broken, from several areas rather than one, means fixings. Broken tiles from a single area usually means impact or a localised defect.
Interwar semis
Bearsted, Loose, Barming and Allington carry substantial 1930s stock where the original bitumen felt is now ninety years old. Felt of that age has typically failed at the eaves and often delaminated mid-slope.
Failed felt does not leak on a dry day, which is why these properties pass a casual look and then admit water in the first wind-driven rain. Re-covering is the only real fix — you cannot replace felt without stripping the tiles — so the decision here is usually about timing rather than whether.
When replacement is oversell
If your roof is under thirty years old, has isolated faults, no nail sickness and sound felt, a re-roof is oversell however confidently it is quoted. We will quote the repair and tell you to come back in a decade.
The same applies to a roof condemned by someone who never went in the loft. Nail condition and felt state cannot be assessed from a driveway, and a replacement recommendation made without that evidence is a guess at best.
We also decline work on roofs that need nothing. A survey concluding that the covering has fifteen years left is a perfectly good outcome and it costs you nothing to hear it.
When patching is money wasted
The mirror image matters just as much. Three £300 repairs in eighteen months on a roof with widespread nail sickness buys nothing — the replacement cost does not reduce, and the interim spend is simply gone.
Re-bedding a ridge on a covering that is itself at end of life is the same error in miniature: money spent on the one part of the roof that was not about to fail.
Our threshold is roughly five years of remaining life and £300 a year of repairs. Below that, replacement is cheaper over any sensible horizon and we will say so even though the repair is the easier sale.
Repair or Replace: The Numbers
| Situation | Recommendation | Typical cost |
|---|
| Isolated fault, covering under 30 years | Repair | £150 - £900 |
| Localised nail sickness, sound slate | Selective re-nail in copper | £600 - £1,600 |
| Under 25% of tiles delaminated | Targeted repair, plan replacement | £150 - £900 now |
| Over 30% failed across slopes | Replace | £5,500 - £15,000 |
| Failed felt on 1930s stock | Re-cover (strip and re-lay) | £5,500 - £11,000 |
| Sound roof, no symptoms | Do nothing | £0 |
A free survey gives you the specific answer for your roof, in writing, with the reasoning stated. No deposit on repairs under £500; staged payments on re-roofs with nothing due before materials arrive. All prices include VAT.
Not sure which side of the line your roof sits? The survey is free and the answer is honest either way.
0162 229 6232
