A commercial roof is leaking: what to do in the first 24 hours
Updated 23 October 2026 · SEO Dons Editorial
What should you do inside the building first?
Water coming through a roof is a hazard to the people and equipment below it before it is a roofing problem. Deal with the space in this order.
- Keep people clear. Close off the wet area and anywhere beneath a stained, bulging or heavily dripping ceiling. Treat a weakened ceiling as unsafe until a competent person has looked at it.
- Treat wet electrics as live. The Electricity at Work Regulations 1989 say electrical equipment that may reasonably foreseeably be exposed to wet conditions must be constructed or protected to prevent danger so far as is reasonably practicable, and that work near a system must not give rise to danger. Water near lights, sockets, distribution boards or IT equipment is a job for a competent electrician to isolate. Nobody should mop beneath a dripping light fitting.
- Stop people walking onto wet floors. The Workplace (Health, Safety and Welfare) Regulations 1992 say a floor must not be uneven or slippery so as to expose any person to a risk. HSE's cleaning guidance says to stop pedestrian access to wet floors with barriers or locked doors, because signs and cones only warn of a hazard and do not prevent people entering the area.
- Check the asbestos register before anything is cut or lifted. HSE says buildings constructed after 2000 are unlikely to contain asbestos, and that the dutyholder must give information on its location and condition to anyone who may work on or disturb it. That includes anyone removing ceiling tiles or boards to trace the leak.
- Protect stock and equipment that can be moved without anyone standing under the damaged area, and cover what cannot.
Why must nobody go onto the roof to look?
A leak makes staff want to check the roof, and that is when people are hurt. HSE says all work on roofs is highly dangerous, even if a job only takes a few minutes, and lists the main causes of death and injury as falling from roof edges or openings, through fragile roofs and through fragile rooflights. It adds that all roofs, once fixed, should be treated as fragile until a competent person has confirmed that they are non-fragile. A wet roof adds to it: HSG33 says rain, ice or snow can make a secure footing as slippery as a skating rink. Regulation 4 of the Work at Height Regulations 2005 adds that work at height must happen only when the weather conditions do not jeopardise the health or safety of the people involved. Once the leak is contained, the commercial flat roof leak repair guide covers the permanent fix.
A leak can also weaken what the roof sits on. HSE's agricultural guidance describes an investigation in which a timber purlin, decayed by water leaking and soaking through the roof, had probably fractured beneath the roof sheets. A leaking roof can be weaker than it looks.
Look from inside instead. Trace the stains and drip points, photograph them, and note where the water appears. HSE's roof work guidance says clients, including those who own, occupy or have responsibility for a building, have an important role when arranging roof work, which includes organising an emergency repair. So tell the contractor what you know before anyone goes up: fragile areas, asbestos entries and the way on to the roof. The CDM 2015 guide covers the client's wider duties, and the commercial flat roof repair guide covers what a competent repair involves.
What should you record for the insurer?
The full evidence checklist and the storm test are in the guide to storm damage and insurance. On the first day, five records matter.
- The date and time you found the leak, and what the weather was doing.
- Dated photographs and video from inside, taken before anything is covered or repaired, and before stock is moved where that can safely wait.
- A list of the affected stock, equipment and areas.
- The contractor's name, what they did, and a written note of what they found.
- Receipts for every temporary measure.
The ABI says to contact your property insurer as soon as possible and, where temporary emergency repairs are necessary to stop damage getting worse, to tell the insurer and keep any receipts, because they form part of the claim. The Financial Ombudsman Service notes that insurers usually have a surveyor's report and that customers sometimes obtain their own, so a contractor's written findings can matter. Whether a leak is covered depends on its cause and the policy, and nothing here predicts that a claim will be paid.
Who else needs to be told?
If you rent the building, tell the landlord or managing agent in writing promptly. The ABI says buildings insurance for rented business premises is the landlord's responsibility, and the lease decides who repairs the roof, as the guide to who pays for a commercial roof explains. Tell any maintenance contractor too, and find the roof's warranty document if there is one, because its conditions may say who may repair the roof. The roof warranty guide explains the types.
What is the difference between a temporary patch and a permanent repair?
| Aspect | Temporary patch | Permanent repair |
|---|---|---|
| Purpose | Stop or slow water entering until the roof can be assessed | Restore the failed detail or area so the roof performs as designed |
| Typical forms | Sealant, a patch or a cover over the entry point | Like-for-like repair or renewal of the failed part, in compatible materials |
| Record | Location, material, photographs, who attended | Cause found, method, materials, photographs, any warranty conditions followed |
| Ask | How long it is expected to hold, and what could make it fail | Whether the wider roof or its insulation is affected |
Who makes the temporary repair matters as much as what it is. The ACR says it is essential that anyone commissioning roof work ensures the company or persons selected are competent to do so. Ask for the contractor's method statement and how it will deal with fragile areas, and ask what it can do and when rather than assuming a time. The SSIP, CHAS and Constructionline guide explains how competence is checked.
The roof sealants guide covers sealants, a common temporary measure. If a patch has to be repeated, ask the contractor whether the roof has reached the stage where the repair or replace decision needs making.
What should the contractor report after the visit?
- Where water appeared to be entering and the likely cause, with any uncertainty stated.
- What was done, with which materials, and what the temporary measure is expected to cope with.
- Whether wet insulation, a damaged deck or other hidden damage is suspected, and what further investigation is recommended.
- Hazards seen on the roof, such as rooflights, corroded sheets, blocked outlets or suspected asbestos materials.
- What access and protection a permanent repair would need.
- Photographs of the defect and the work.
Ask for it in writing, and ask when the contractor recommends the temporary measure be reviewed. A verbal assurance that a patch will hold is not a record. If you want a contractor's view on a leaking roof, you can send an enquiry through the form on this site.
Sources
- legislation.gov.uk, checked 22 October 2026: Electricity at Work Regulations 1989 regulation 4 and regulation 6; Workplace (Health, Safety and Welfare) Regulations 1992 regulation 12; Work at Height Regulations 2005 regulation 4
- HSE, checked 22 October 2026: Roof work, Fragile surfaces, Falls through fragile roofs, Slips and trips (cleaning), Introduction to asbestos safety, Duty to manage asbestos and HSG33 Health and safety in roof work; Advisory Committee for Roofsafety IS1 Clients guide
- Association of British Insurers: Storms and Commercial property insurance; Financial Ombudsman Service: Storm damage, checked 22 October 2026
Common questions
Can staff put a sheet or tarpaulin over the leak?
Not if it means going onto the roof. HSE says all work on roofs is highly dangerous even when it only takes a few minutes, and the Work at Height Regulations 2005 allow work at height only when the weather does not jeopardise the safety of the people involved. Inside the building, staff can usually divert and catch water and cover stock with sheeting, provided they stay clear of wet electrics and weakened ceilings.
Should I call the insurer before or after the roofer?
The ABI says to contact your property insurer as soon as possible and, if temporary emergency repairs are necessary to stop damage getting worse, to tell the insurer and keep the receipts. Read the policy wording for any notification conditions, take dated photographs before anything is covered or repaired, and keep the contractor's written findings.
What if the building is let and the roof is the landlord's?
Tell the landlord or managing agent in writing, as the lease requires, and tell your own insurer. The ABI says buildings insurance for rented business premises is the landlord's responsibility. The lease decides who repairs the roof, so check its repairing and service charge wording before arranging anything beyond emergency protection.
Will a temporary repair affect the roof's warranty?
That depends on the conditions of the warranty, which is a separate document with its own issuer and terms. Find it before any permanent repair, check what it says about who may repair the roof and with what, and ask the contractor to confirm in writing what was done and with which materials.