Question answered
Repair or re-slate? How to decide
The short answer
Repair a slate roof if the fault is confined to one spot and the fixings and battens behind it are sound. Re-slate when slates are slipping or breaking over an entire slope, with nails rusting through or battens rotten, because repeated patching then costs more than it saves. The survey decides, by checking how many slates have failed and what lies underneath them.
A slate roof can often be repaired, and sometimes it cannot. The decision rests on the extent of the failure and on what is holding the slates on, not on the roof's age alone.
The questions the survey answers
Three things decide it. The first is how many slates have failed, and whether they are clustered or scattered. A cluster around a chimney points to a flashing; a scatter across a slope points to the fixings. The second is the condition of the nails, which is what holds slates on. The third is the battens, the timber laths beneath the slates, because a sound slate on a rotten batten is not a sound roof.
We also check for underlay, since many older roofs have none and rely on torching, and look at the lead, ridge and gutters. Each of those can be repaired without touching the slates. In the loft we follow stains and damp timber back to the source, then show you pictures taken on your own roof so the evidence is in front of you before any quote is written. Only then can the choice be a fair one, made on facts you have seen.
Where repair is enough
A repair suits a roof with mostly sound slates and one confined fault. A handful of slipped slates, a split valley liner, a worn flashing or a crumbled ridge can each be fixed on its own. Tap-testing a slate is part of the process: a ringing note suggests a sound slate and a dull one a crack.
The saving is real. MyBuilder's repair guide (21 August 2026) puts typical jobs at £150 to £1,500, with major work at £2,500 or more, set against thousands for a re-roof. The causes and fixes are set out in slate roof repairs.
One caution applies. A repair only lasts if the next slate along is held by a sound nail. Where one slate has slipped because its nail rusted, its neighbours were nailed at the same time, so we test those nearby before saying the fault is isolated. That small check is what separates a lasting repair from one that fails at the next gale.
When re-slating is the better answer
Re-slating means stripping the slope, renewing battens and underlay where needed, and relaying the slates, reusing the sound ones and topping up with matching stock. It becomes the better option when failure is general. Nails rusting across a slope, slates delaminating in layers, battens soft with rot, or a pattern of repairs that keep reappearing all point the same way.
Fixings need thought on an exposed roof. Slates relaid to the right gauge, with fixings chosen for the exposure, hold in a gale where the old ones slipped; fixing slates on an exposed roof covers that. For the wider cost picture, MyBuilder gives £100 to £180 per m² for slate, and Checkatrade puts a re-roof scaffold at £700 to £1,300; the comparison is in slate against tile cost.
Man-made slates age differently, and fibre cement slate lifespan explains how to judge them.
What the rules say about a full re-slate
According to the Planning Portal, a building control application is not normally needed if less than 25 per cent of the building envelope and less than 50 per cent of the roof is affected. Re-slating a whole roof goes beyond that, so approval applies. The same guidance warns that exceeding the limits can raise further questions, among them whether the insulation is adequate.
That is why loft insulation can come into the job. We explain what is notifiable and handle the Building Regulations notification through a registered building control approver or the council's team, as the work requires.
Relaying in the same material seldom calls for planning permission, yet a listed building or a home under an Article 4 direction carries extra rules, and the Adur & Worthing planning team can confirm which apply. Our slate roof lifespan page helps you weigh how much life the old roof has left.
Weighing it up
A useful test is to ask what a repair would buy. If it cures the fault and everything around it is in good order, it buys years at modest cost. If the same repair would be needed again within a few seasons, it buys little. Slate is a durable covering, but it is not free of drawbacks, and slate roof disadvantages sets them out plainly.
Recommending the smaller job is part of how we work: we find the cause first and say which route fits, with the reasons. Pictures from the loft and the slope come with a written quote that closes on a single sum. If the roof is leaking, we make it safe first, and you decide on the permanent work with everything in front of you. The full set of slate services sits under slate roofing.
Repair or re-slate: two more questions
Can my existing slates be reused when a roof is re-slated?
Often, yes. Sound slates are sorted, cleaned and relaid, and shortfalls are filled with reclaimed or matching stock. Slates that crack when lifted or have delaminated are rejected. The reclaimed supply and the colour match are covered in our guide to matching old slates.
Does a repair affect the age of the rest of the roof?
No. A repair fixes one fault and leaves the remaining slates as they were. If their nails are close to failing, the roof can still need work soon, which is why we test the fixings around any repair and say what the survey finds.
Tell us about your roof
Describe what is happening and we will call you back to arrange a visit.
- Photographs of what we find
- A written quote with one total price
- Or call 01903 299063
10-year workmanship guarantee, in writing.