Comparing three quotes on a 2,400 m² warehouse re-clad

This is a representative, modelled scenario rather than a named client, but it is the single most common problem we are asked to untangle: a facilities manager holding three commercial roofing quotes for the same roof, ranging from a £48,000 liquid coating to a £310,000 full re-clad, with no way to tell which one is honest. The headline numbers differed by more than six times, and the temptation was to reach either for the cheapest to protect the budget, or for the dearest on the assumption that more money meant a better roof. Both instincts were wrong, because the three firms had not quoted the same work.

Why the three quotes were never comparable

The building was a 2,400 m² distribution warehouse with a leaking profiled-metal roof, and reactive patching over the picking aisles had become an annual line in the maintenance budget. The three quotes told three different stories. The £48,000 coating proposed to seal the surface and buy a few years. A middle quote proposed a mix of gutter and cladding works. The £310,000 quote proposed to strip the roof entirely and re-clad it. None of them explained why the roof was actually leaking, because none of the numbers on the page were built from a survey — they were priced from a rate card and an assumption.

What the survey found

A survey from the deck up settled the specification, and it did not match any of the three assumptions cleanly. The profiled metal sheets themselves were structurally sound — the roof did not need stripping. But the valley gutters had failed at the joints and laps, and cut-edge corrosion had taken hold at the sheet ends, which is the classic failure point on an ageing profiled roof. The water was coming in through the gutters and the corroded laps, not through the sheets, which is exactly why repeated sheet-focused patching had never stopped the leak. The gutter and cut-edge failure was the diagnosis, and it sat entirely outside the £48,000 coating’s scope.

The honest specification, between the extremes

The right answer sat between the cheapest and the dearest quote. The specification combined three works: a cold-applied liquid gutter lining to seal the valley gutters to their outlets, cut-edge corrosion treatment at the sheet ends and laps, and an over-sheet to a new insulated built-up cladding build-up over the sound existing sheets — which fixed the actual fault and, crucially, added a Part L thermal-element upgrade to a U-value of 0.18 W/m²K that the coating would never have delivered. The whole scope came in at around £140,000: three times the coating, but less than half the full re-clad, and the only option that both stopped the leak and improved the building.

The coating would have sealed the surface and left the gutters leaking — money spent that would not have fixed the problem. The £310,000 re-clad over-specified a roof whose sheets did not need replacing, spending capital that the survey did not justify. The over-sheet route delivered a new insulated roof over the sound deck, upgraded under Approved Document L, without the cost and waste of a full strip.

Delivered occupied, in about six weeks

Picking continued below throughout. The works were phased so the warehouse stayed operational, the wind-uplift fixing was calculated to BS EN 1991-1-4 with enhanced perimeter and corner zones, and the work was carried out by a manufacturer-approved, NFRC-accredited installer. It was backed by up to a 25-year single-point manufacturer guarantee, subject to system and approved-installer status — not a workmanship promise, and never described as a lifetime guarantee, because a guarantee is always bounded by a term.

The lesson

Three commercial roofing quotes for the same roof will very often price three different scopes, and the cheapest is frequently the one that leaves the underlying fault in place. The only way to compare them like with like is from a survey that reads the roof from the deck up and identifies why it is actually leaking. The figures here are modelled to illustrate the method, not a named client. If you are holding quotes that do not add up, request a survey-based quote and get all the options — repair, refurbish and replace — side by side with honest costs before authorising anything.