A leak does not automatically mean a new roof. A local repair can be the sensible choice when the failed detail is isolated and surrounding materials remain serviceable. Replacement becomes more credible when defects are widespread, several systems have failed, opening-up reveals broader deterioration or repeated repairs have not addressed the route.
Ask for both the repair case and the replacement case
For a repair, ask what will be retained, what will be changed and why the surrounding roof should continue to perform. For replacement, ask for evidence of the wider condition and a complete specification. Age is context, not a diagnosis.
Compare hidden-risk allowances
Both options can uncover rotten battens, decking, timber or wet insulation. The quote should explain which inspection is possible before work, which allowances are included and how extra work is approved. A replacement price without access, protection, disposal and making good is not a complete comparison.
Keep documents useful
Ask for photographs, materials, product information, building-control records where applicable and a clear workmanship guarantee. Consider disruption and scaffold as well as the headline total. The better decision is the one supported by condition and a defined outcome.