The edge is where Gloucester’s steel roofs fail first
We’ve worked on industrial roofing all over Gloucester, from older sheds down by the docks and railway lines to post-war workshops and newer distribution units along the M5 corridor. They’re all different ages, but the detail at the edge is always the same. Steel sheets are cut to length when they’re made, that cut exposes the raw steel core, and the factory coating stops right there. Cut edge corrosion is just rust taking hold on that unprotected edge, then creeping back under the coating.
You’ll usually spot it as a brown line along the eaves or staining where the sheets overlap. By the time you can see it clearly from the ground, the coating above it has almost certainly started to lift.
The Severn Vale does not help
The Vale is a damp place, and that’s not good for steel. Mist off the river, long humid spells, and persistent winter wet mean moisture just sits in the laps between sheets. Capillary action already draws that onto bare cut steel. Joints that never properly dry out corrode steadily, even when the weather’s mild. The expanding rust levers the factory coating away from the metal, and that just exposes more steel to the next wet spell.
Older roofs fare the worst. If a roof has already lost its coating’s gloss and flexibility, it hasn’t got many defences left. Edge corrosion moves a lot faster on a tired coating than it does on a younger one.
The early-versus-late gap
If we treat the corrosion while it’s still shallow, it’s a localised repair. We abrade the edges back to sound steel, prime them, seal the laps, and apply a flexible coating band over that vulnerable zone. The building can keep trading underneath while we do the work.
Wait too long, and the steel thins until it punctures. Then you’re talking about replacing sheets, getting in specialist access equipment, and interrupting whatever the building does. The cost multiplies accordingly. This defect gives you a long window to act cheaply, and a very short one after that. Our survey tells you exactly where your roof sits in that window.
A corrosion paint system on a Gloucester roof only works over properly prepared edges. Treatment first, then the protective coat.
Sometimes the right advice is not a coating
We always put the survey before the quote because some roofs around Gloucester are simply past treating. Perforated sheets, laps with serious metal loss, or corrosion on the underside of the sheets all rule a coating out. We’ll tell you that directly; we won’t try to dress it up. Your workable options then are replacing the failed sheets and treating the sound ones, or an overlay or full re-sheet if the whole roof is finished. You’ll get our photographs and our reasoning either way, so nothing rests on a salesman’s opinion.
What the survey records before anything is recommended
- Condition of accessible cut ends, side laps and end laps
- How far rust has travelled beneath the coating
- State of fixings, flashings and gutter lines
- Coating condition across the sheet faces: chalking, cracking, fade
- Whether edge treatment alone or a full roof coating is better value
That last point really matters. If the coating across the whole roof is tired, just treating the edges in isolation means the rest will fail on its own schedule. A full roof coating with cut edge treatment built in is usually the sounder spend. We’re based in the South-East, but we cover the whole of the UK, and Gloucester sits comfortably within our working area. If you’ve got rust at your sheet ends, the survey is the place to start.
