Recurring water ingress, ponding, visible membrane distress, corroding metalwork and damaged gutters are reasons to investigate; they are not, by themselves, proof that replacement is required. Keep people away from suspect areas and arrange safe inspection.
What a survey should establish
A useful report records the roof construction, defects and locations, drainage and falls, signs of moisture, safe access constraints, interfaces and recommended next investigations. It should distinguish urgent temporary measures from planned repair, overlay or replacement options.
Act safely
Roof access and fragile surfaces present significant risks. HSE guidance on work at height should inform access planning and controls. If asbestos-containing material is suspected, use the asbestos register and obtain competent advice before disturbing the fabric.
Choose an owner for the next step
For flat-roof membrane options see liquid waterproofing. Metal-sheet edge deterioration may need cut edge corrosion treatment; gutter defects may need commercial gutter lining.