What does a roofer check when diagnosing roof damage?

The covering is assessed for movement, cracking, delamination and surface loss, and the fixings for corrosion and whether components are held as intended. Then the details: ridge, hips, verges, valleys, abutments, chimney flashings, roof lights and pipe penetrations.

Details deserve most of the attention because they carry concentrated water and involve more than one material meeting.

Gutters, valleys, outlets and downpipes are checked for flow, fall, blockage and joint condition, because water that cannot get away is a frequent underlying cause rather than a side issue.

Inside, the roof space shows staining, damp insulation, timber condition, ventilation and any daylight. It is also where condensation is distinguished from ingress, which changes the recommendation entirely.

The line of the roof, the condition at bearings and any previous alterations are noted, because structural findings change the priority of everything else. So does history: previous repairs, the age of the covering, and what the owner has already been told.

The output should be a written record separating what was observed from what is inferred, with dated images, so you can see the reasoning rather than just the conclusion.

These six areas are not independent checklist items; a finding in one usually changes what is looked for in another. Blocked drainage found early, for instance, redirects attention towards water backing up at an eaves or valley rather than assuming the covering itself has failed. A structural note about bearing condition can explain why fixings in that area have loosened even though the covering looks sound.

This is why a diagnosis carried out properly takes a little longer than a quick look at the obvious symptom, and why the order in which things are checked matters as much as whether they are checked at all.

A proper diagnostic visit should leave you with more than a verbal summary. Dated photographs of what was found, a note of which of the six areas were actually accessed, and a plain statement of what is inferred rather than directly observed are all reasonable things to ask for before any repair is agreed.

Where access was limited on the day, for example a locked roof space or a section that could not safely be reached, that should be recorded too, rather than quietly left out of the report. A report that is silent about what it did not cover reads the same as one that covered everything, which is precisely the gap that leads homeowners to commission work based on an incomplete picture without realising it.