Guide
Commercial roof repair cost: when to patch and when to stop patching
Updated
A leak over a warehouse aisle is an urgent, small, awkward job. Small and awkward is the expensive combination, which is why repair pricing looks so different from replacement pricing.
Why small roof jobs are not cheap
- Access dominates. Getting safely onto a fragile industrial roof for two hours costs much the same as getting onto it for two weeks. HSE states effective precautions are required for all work on or near fragile surfaces no matter how short the duration.
- Finding it takes longer than fixing it. Water tracks along purlins and liners and appears metres from the defect. Leak tracing is a genuine skill and a genuine line in the price.
- Short maintenance jobs are the dangerous ones. HSE states that those carrying out small, short-term maintenance and cleaning jobs are over-represented in the fragile surface injury statistics.
- Reactive means premium. A same week callout during a storm is priced differently from planned work in the summer.
The usual suspects on an industrial roof
| Where it leaks | Typical cause | Repair or replace? |
|---|---|---|
| Sheet laps and end laps | Failed sealant, capillary action, or sheets that have moved | Repairable while the sheets themselves are sound |
| Fixings | Corroded fixings and perished washers, often across a whole elevation at once | Repairable, but widespread failure signals the roof's age |
| Rooflights | Age, brittleness and crazing; also a fragility hazard HSE names specifically | Usually replace rather than patch, and specify non-fragile |
| Gutters and outlets | Joint failure, ponding, blockages and undersized outlets | Lining or replacement, and often the cheapest real fix available |
| Penetrations and flashings | Plant, ducts and cable trays added over the years without proper weathering | Repairable, and worth auditing after any roof plant installation |
| Corroded sheet | Age, coating failure and edge corrosion, especially near coastal or industrial atmospheres | Patching buys time; widespread corrosion means the roof is at end of life |
The point where repairs stop making sense
There is no rule and anyone quoting a percentage of replacement cost as a threshold is making it up. The honest test is a practical one: if you are repairing a different part of the same roof more than once a year, if fixings or corrosion are failing across whole elevations rather than in spots, or if the insulation is wet, you are funding a replacement in instalments and getting no warranty for it. At that point, price both and compare. See replacement costs and overclad versus strip.
Before anyone goes up there
The Work at Height Regulations 2005 apply to you as well as to the contractor. HSE states the purpose of those regulations is to prevent death and injury caused by a fall from height, that they apply to employers and to those who control work at height, giving facilities managers and building owners who contract others to work at height as the example, and that those in control must make sure work is properly planned, supervised and carried out by competent people (HSE). The regulations themselves are on legislation.gov.uk.
Leaking now? Say so in the form and contractors will prioritise it. Get repair quotes.