Last reviewed: 2026
Repair is usually right when the failure is localised and the rest of the covering, battens and fixings are sound. Replacement becomes the better value option when defects are spread across the roof, the battens or nails are failing, or repeated repairs keep buying only a season or two.
When repair is the sensible option
A roof that has lost a handful of slates in a gale, has a failed flashing or has one leaking valley does not need replacing. These are contained problems with a defined cause, and repairing them properly restores the roof for years.
- The covering elsewhere is sound and consistent in condition
- Battens, fixings and underlay in the affected area are still serviceable
- The defect has an identifiable cause rather than being general wear
- Matching material is available so the repair does not stand out
When replacement is usually better value
Nail fatigue is the classic case: slates start slipping in ones and twos across the whole roof because the fixings — not the slate — have reached the end of their life. Repairing that roof is an ongoing cost with no end point.
- Slipped units appearing repeatedly, in different places each time
- Battens that are soft, split or under-sized when exposed
- Underlay that has perished and no longer sheds incidental water
- Multiple previous patch repairs in mismatched materials
- Structural movement, sagging ridge lines or spreading rafters
The questions worth asking any roofer
Ask what was actually found, and to see the photographs. Ask whether the recommendation addresses the cause or only the symptom, and what would need to happen for the cheaper option to be viable. A contractor who can answer those calmly is giving you a scope, not a sales pitch.