How do I know whether my roof should be repaired or replaced?

A defect is isolated when the surrounding covering, fixings and details are sound: a cracked slate, a lifted flashing, a blocked valley. Repair is the proportionate answer, and it will last.

A defect is general when the same failure keeps appearing for the same underlying reason — nails corroding across a slope, underlay perished throughout, battens softened. Repairing one instance does not change the condition of the rest, which is why repeated repairs on such a roof feel like money down a drain.

Maintenance handles debris, vegetation and drainage. Local repair handles isolated defects. Partial renewal takes one slope, valley or ridge line back to a sound condition. Substantial repair addresses structure or several details at once. Replacement renews the whole covering. Further investigation is the right answer whenever the extent cannot be established.

Presenting only the first and last of those, as if the choice were patch or new roof, is where most homeowners are poorly served.

For a replacement recommendation to be sound, it should rest on findings that apply across the roof: fixings failing generally, underlay perished, battens deteriorated, or structure needing work that requires stripping. Those are specific, checkable statements.

Where they are not present, the honest answer is repair or partial renewal — even if a larger job would be more profitable for the contractor proposing it.

Repair is cheaper now. Whether it is cheaper over ten years depends on how many more repairs the roof will need, and on access costs each time. Where scaffolding is required for every visit, three repairs can approach the cost of renewing a slope once.

Ask for both figures and for a view on remaining serviceable life. That is a judgement, not a guarantee, and it should be presented as such.