How Often Should a Commercial Roof Be Inspected?

Start with the paperwork. A manufacturer's warranty on a single-ply membrane or a profiled metal system often makes cover depend on inspections at stated intervals, and a full repairing lease may do the same. If either names a schedule, that schedule is your minimum, and missing it can cost you when a claim or a dispute arrives. Our page on the commercial flat roof warranty explains what such conditions tend to ask of the owner.

Without a stated schedule, think about the roof itself. A roof nearing the end of its service life needs more frequent visits than one laid recently. A flat roof with outlets, upstands and internal box gutters has more places to fail than a simple pitched sheet roof. Roofs crossed by engineers servicing extract fans, air handling units or aerials pick up foot damage that nobody reports. Trees nearby fill gutters with leaves, and a unit beside a busy yard collects grit and debris.

For most owners, a planned visit in the quieter part of the year, before the wet season, works well, with an extra look whenever a storm has passed over the site.

A good inspection starts at ground level. The inspector looks at the building from the yard, checks the rainwater pipes, and asks what the occupiers have noticed inside: stained ceiling tiles, drips after heavy rain, damp patches on a back wall. Then comes the roof itself.

On a membrane roof, that means the laps and seams, the upturns at parapets and plant bases, the outlets and the condition of the surface where it is walked on. Ponding water is worth noting, because a flat roof is meant to be laid to a fall and standing water suggests it is no longer shedding properly. On a metal sheet roof, the checks run to fixings, sealed laps, rusting along cut edges, and the rooflights, which are often the weakest and most dangerous part of the roof. Gutters, hoppers and overflows are cleared and tested, since a blocked outlet causes more water damage than most defects.

Access must be safe. Many industrial roofs are fragile, and an inspector should never step on a rooflight or an unknown sheet. Our guide to fragile roof safety sets out why.

The record is as valuable as the visit. Months later, when a tenant complains or an insurer asks questions, a dated report with pictures settles arguments that memory cannot. It should name the building and the roof areas covered, the date, who carried out the inspection and how they reached the roof. It should list each defect found, say where it is, and show a clear photograph of it.

Each finding needs a recommendation in plain words: leave and recheck, repair now, or plan for renewal. Where something was too dangerous to reach, say so instead of guessing. Note the condition of drainage, and record any work already done since the last visit, so a clean history builds up over time.

Keep the reports with the lease and the warranty. A series of reports also helps you budget, because a roof that is slowly declining can be planned for, rather than discovered through a leak on a Monday morning. For a deeper review of an ageing roof, a full commercial roof condition survey goes further than a routine visit.

Some events call for a visit whatever the calendar says. After a storm with high winds, check for lifted sheets, displaced flashings and debris on the roof. After heavy rain, look for new staining inside. Before you sign or end a lease, buy a unit or let it, a roof report gives everyone a clear picture of the starting condition. After any work by other trades on the roof, such as solar installers, aerial fitters or air conditioning engineers, have the area checked, because holes and loose fixings are easy to leave behind.

Spotting an issue between visits is no reason to wait. Water marks that grow, daylight through a ceiling void, or sheets that rattle in the wind should be looked at promptly. A small repair to a seam or a sealed lap often costs little, while a long-running leak can soak insulation and damage stock or equipment.

If you are unsure what your roof needs, send us the address, the type of building and any previous report. We will say what to look at first and how the roof would be reached safely. Blocked outlets do the most harm between visits, and the wider commercial roofing page covers the repairs that follow.