The short answer
Most commercial roofs should be inspected twice a year, in spring and in autumn, and again after any severe storm or after other trades have worked on the roof. Autumn catches leaf-blocked drainage before winter. Spring finds frost and wind damage. Older roofs, roofs with plant and foot traffic, and roofs under manufacturer warranty may need more frequent visits, and the warranty terms often set a minimum. Keep a written record every time.
The routine that suits most roofs
A twice-yearly visit is a practical rhythm because the roof faces two different threats. In autumn, leaves, seeds and moss collect in gutters and outlets, and a blocked outlet during winter rain is the quickest way to flood a flat roof and its building. After winter, frost, wind and the weight of snow have tested every lap, seam and fixing, so spring is the time to find what moved. Extra checks after a severe storm are sensible too, since high wind can lift edges and flashings and throw debris onto the roof.
Some roofs need more. A roof that is nearing the end of its life, a roof with a history of leaks, and a roof carrying plant, solar panels or walkways, where people go on it regularly, are better visited more often. Check also what your manufacturer's warranty says. Many require an annual inspection by a competent person and a record of repairs, and a missing record can cause a claim to fail.
What an inspection looks for
The inspector walks the whole roof, or inspects it from a safe platform or by drone where walking is dangerous. On a flat roof, the list includes ponding, blistering, splits, open seams and laps, damaged upstands and flashings, cracked or loose parapet copings, and the condition of outlets and gutters. On a sheeted roof, it covers loose or missing fixings, open laps, corroded cut edges, damaged sheets, cracked or crazed rooflights, and failed sealants. Our page on cut edge corrosion on metal roofs shows what early rust looks like.
Drainage gets special attention. Outlets are cleared, gutters flushed and overflows checked. The inspection also notes anything added since last time, such as new pipework, aerials or cable runs, because every new penetration is a new place for water to get in. Photographs are taken at each stage, so changes show up from one visit to the next.
Seasonal checklist
In autumn, concentrate on water: clear every outlet, check the gutters run freely, look at the roof edges for lifted trims and make sure leaf guards, where fitted, are intact. In spring, concentrate on movement: look for cracks at parapet joints, lifted laps, split seams and any sheet that has shifted. Whatever the season, look inside the building too. Fresh stains on ceilings, damp insulation at the eaves and rust on purlins often show a problem before the roof surface does.
Ask the person doing the inspection to rate each finding, so you can tell an urgent fault from one to watch. A short list ranked by urgency, with photographs, is far more useful than a long narrative, and it makes budgeting for next year straightforward.
Safety first
Inspecting a roof is work at height, and the Work at Height Regulations 2005 apply. Many commercial roofs have fragile sections, and the risk is highest on old rooflights and corroded sheets. The inspection should be planned, with safe access, edge protection or restraint, and no lone working. A caretaker with a ladder is not the right answer. Our page on fragile roofs and rooflights sets out what safe access involves, and roof edge protection covers the edges.
What to keep on record
It also helps to log access. Note who went on the roof, when and why, because contractors for air conditioning, solar, aerials and signage all walk on it, and each visit can cause damage that shows up months later as a leak. Ask them to report anything they disturb.
Keep a roof file. It should hold the drawings or specification, the manufacturer's warranty, the asbestos register entry if the roof is old, and a dated report from each inspection, with photographs and a list of repairs. When a leak appears, that history lets a roofer see whether the cause is new or the same weak point returning. Landlords and tenants should both hold a copy where the lease splits the roof duties, which our page on who repairs the roof discusses.
Small repairs found at inspection, such as a re-sealed lap or a replaced fixing, are cheap compared with the damage from a leak over stock. For the wider approach to upkeep, see planned maintenance for commercial roofs.
We begin with a free survey and photographs of your own roof, so you can see its condition for yourself. If it needs only a clear-out and a few repairs, we tell you that and quote a fixed price. The hub for all our business premises work is commercial roofing in Basingstoke.
Every roof is different. A free survey with photos settles it for yours.
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