Commercial roof surveys

The first pass is the covering itself. On a profiled metal or fibre cement roof that means the sheets, the side laps, where neighbouring sheets overlap, and the end laps, where a sheet runs beneath the one higher up the slope. On a flat roof it means the membrane, the seams, the upturns at the walls and any blisters or splits.

Then come the details that let water in more often than the open field does. Ridge and eaves flashings, parapet copings, pipes and flues that pass through the roof, extractor fans, roof hatches and plant bases all get a close look, because each one is a break in the waterproofing. Sealant that has shrunk, cracked or pulled away is recorded with a photograph.

Fixings are checked sheet by sheet where access allows. Rusted heads, missing washers and screws that have backed out of the purlin are common, and they cost little to put right when caught early, though a full set of failures on an old roof tells a different story.

Much of the evidence sits below the roof. From the floor or a safe platform, the surveyor looks for daylight at laps, drip marks on racking and stock, rust bloom on the underside of metal sheets, and stained or sagging insulation. Wet insulation matters because it stops insulating and starts holding water against the steel.

The purlins and rails that carry the sheets are checked for corrosion and movement. So are the fixings that hold the roof to them, since a sound-looking covering on a tired frame is not a sound roof.

Condensation is separated from leaks at this stage. Drips that appear on cold mornings and clear by midday point to moisture forming on the underside of the sheet, not to a hole above. The fix for each is different, which is why the interior check is part of the survey and not an optional extra.

Drainage decides how long a roof survives, so the survey traces the water's path from the sheet into the gutter, along any valley or parapet gutter, through the outlet and down the pipe. Silt, leaves, moss and old packaging collect in the low spots, and a blocked outlet will turn a gentle shower into a puddle on a flat roof.

Linings in old box gutters get close attention, because a cracked lining there can leak into the wall below for months before anyone notices. Our page on industrial gutter lining covers what can be done with them.

Overflows are checked too. If a main outlet blocks, an overflow is the only thing between a full gutter and water pouring over the parapet or into the building.

Rooflights are inspected for cracking, crazing and loose fixings, and treated as fragile until proven otherwise. Nobody should walk across an old rooflight, and the survey is planned around that. Our page on replacing rooflights on an industrial unit explains the next step if they are failing.

Age matters for the sheets as well. For buildings put up or refurbished before 2000, HSE says to presume asbestos is there until a test shows otherwise. A cement sheet roof from that period is therefore handled as suspect until it is confirmed otherwise, and the survey notes where it sits. Our guide to asbestos cement roofs on commercial buildings goes through the rules.

Access is agreed beforehand: ladders, a cherry picker or a roof ladder, and crawl boards across anything that could give way.

Most commercial roofs belong to buildings with people inside them. A survey is arranged for a time that suits you, with as little disturbance to staff, deliveries and customers as the layout allows. If a loading bay or a yard needs to be kept clear for ladder access, we tell you before the visit.

Where repairs follow, the same thinking applies. Our page on repairs while a business stays open shows how repairs can be phased around the working day.

If a leak is already coming through, we prioritise it and make the area safe first, then survey the rest of the roof properly once the water is under control.

The report comes back as dated photographs of the points described above, followed by a written quote. The quote covers the work the survey supports. Where we can, we propose a modest, targeted fix, and on many commercial roofs that means a targeted repair and not a new covering. Findings are grouped by urgency, so you can see what to do this month and what can wait for a planned visit.

For a rough national picture, MyBuilder's roof inspection guide, updated on 21 August 2026, puts inspections generally at £150 to £500 depending on the type, with drone surveys at £200 to £400. Those are typical UK figures for a roof inspection, not a price for your building, and a large industrial unit can sit outside them.

If you are a landlord or tenant who needs to know who pays for what, read our guide to commercial landlord roof repairs alongside the survey. Our commercial roofing page covers the wider service, and any repair we carry out comes with our 10-year written guarantee on the workmanship.