When is a roof beyond economical repair?

Compare the likely cost of repairs over the next five to ten years, including access, against renewal now. Scaffolding is often the dominant figure: if it is needed each visit, several repairs can cost more than doing the work once.

Then ask how much time each repair buys. Repairs on a roof with sound fixings last years. Repairs on a roof whose nails are corroding buy months, because the next slate is already on its way.

Slates releasing in unrelated places across a slope. Underlay that tears when touched, or none at all combined with driven-rain ingress. Battens soft at several points. Fixings corroded wherever they are exposed. Each of these is checkable, and together they describe a roof at the end of its serviceable life.

One of them on its own usually does not. A single soft batten under a long-standing leak is a repair.

Age alone. Moss. A single storm loss. Some slate coverings remain serviceable well beyond a century, and roofs are frequently replaced years before they need to be because the covering looks tired.

Where a contractor cannot point to general failure of specific components, ask what a repair strategy would cost instead and how long it would be expected to hold.

Ask each contractor for two figures rather than one: what a further round of repairs would cost over the next few years, including access, and what full renewal would cost now. Few homeowners ask for both, so few contractors offer both unprompted, and the comparison is the whole point of the exercise.

Where a contractor resists giving a repair figure, that itself is informative. A roof genuinely beyond economical repair should make its own case once the two numbers sit side by side, without needing to be argued into a renewal.