Roof repairs & maintenance

Steel roofing does not rust evenly. It starts at cut edges, at sheet laps where moisture is held by capillary action, around fasteners where the coating has been broken, and anywhere debris sits and stays wet. That is why a roof can look sound from the ground and be finished when you get up to it.

The judgement is straightforward. Localised rust, typically around a penetration or in a valley, is a repair: cut out, treat, replace the affected section. Rust breaking out along laps and fixings across the whole roof means the coating has done its time, and further patching is spending money on a roof that needs replacing.

Painting over a rusting metal roof is worth being sceptical about. On a sound roof with early surface corrosion, correctly prepared and coated, it can buy real time. Sprayed over active rust and flaking coating without preparation, it is cosmetic, it lasts a season or two, and it makes the roof harder to assess afterwards.

After a storm the first priority is making the building safe and watertight, which is a different job from repairing it. Temporary weatherproofing stops the damage compounding while the claim is sorted out, and insurers generally expect you to mitigate rather than let it run.

What helps a claim is evidence. Photographs of the damage taken safely from the ground, a written report describing what failed and how, and a clear separation between storm damage and pre-existing wear. That last distinction is where most disputes live, and it is far easier to argue with documentation than from memory.

The safety point is not a formality. After high wind, sheets can be lifted and held only by a few fasteners, and a lifted sheet edge will take fingers off. Stay on the ground and let someone with harness and anchor points deal with it.

Roofs fail at details, and details are inspectable. Clearing valleys and gutters before winter, checking and replacing perished fastener washers, resealing penetrations before the sealant fails rather than after, and treating early rust while it is still localised, are all inexpensive compared with the ceiling, insulation and cabinetry that a slow leak destroys.

On commercial buildings this becomes a scheduled programme with a written condition report each time, which also gives the owner something to hand an insurer or a prospective tenant. On houses it is generally an annual look, and more often under heavy tree cover.