Metal Cladding Spraying: What Decides the Cost, the Finish, and Whether It’s the Right Call

If you have asked two or three contractors about metal cladding spraying, you have probably heard the same pitch: it costs a fraction of replacement, it avoids the disruption of a re-clad, it can be done while the building stays open, and it comes with a warranty. All of that can be true. None of it is a decision framework.

What a buyer actually needs to know is narrower. Is this building a realistic candidate, or is spraying going to put a cosmetic finish over a failing envelope? Why does one quote arrive at twice the number of another on the same elevation? What does in-situ work do to a live site? And what is that warranty figure resting on?

Why nobody can give you a square metre rate

Any contractor who quotes a flat rate per square metre before seeing the building is guessing, and the guess will be corrected later. The variables below are not add-ons. They are the job.

Panel type and profile. A flat composite panel elevation and a deep trapezoidal profiled sheet elevation are not the same quantity of work even at identical elevation areas. Profiled sheet has considerably more surface area than the flat measurement suggests, and the ribs change how the coating has to be applied to get even coverage across crowns and troughs. Curtain walling with lots of mullions and transoms is closer to fine work than broad-acre spraying.

The elevation geometry, not just the area. Two thousand square metres of uninterrupted warehouse flank wall is efficient work. The same area broken up by glazing, louvres, roller shutters, signage, downpipes, flashings, service penetrations and a canopy is not, because every interface is masking, and masking is labour that produces no coating at all. When a quote looks high for the area, the interfaces are often the reason.

Condition, which is really the preparation cost. This is the single largest swing factor. Cladding that has faded and chalked but is otherwise clean and sound needs washing, degreasing, abrading and priming. Cladding with widespread flaking, spot corrosion at fixings, failed sealants and an unidentified previous overpaint needs all of that plus mechanical removal of failed material, spot treatment and remediation. The coating hours barely change between those two buildings. The preparation hours can multiply.

Access. Height, ground conditions and what is happening below the elevation decide whether you are working from a mobile elevating work platform, scaffolding, a mast climber or rope access. A yard in constant HGV use, a live car park, a railway boundary or a neighbouring occupied property all constrain the access solution and the hours it can be used. Access frequently carries a meaningful share of the total.

Colour change. Refreshing a building in a similar shade is straightforward. Taking a dark elevation to a light one, or moving to a strong saturated colour, can require additional coats to achieve opacity, which changes both material and programme. If a rebrand is driving the work, say so early: it changes the specification, not just the colour reference.

Specification and working pattern. Primer choice, number of coats and target film thickness all carry cost, so two quotes can describe the same visual outcome while sitting on very different systems. Night work, weekend work and restricted access windows also reduce productive hours, and fewer usable hours per day means more days on site.

Which cladding is a realistic candidate, and which is not

Spraying is a coating operation. It renews the finish. It does not repair the building.

Reasonable candidates are sound coated steel and aluminium panels where the original factory finish has weathered rather than failed: fading, chalking, loss of gloss, general grubbiness, patchy appearance after repairs. Powder coated aluminium, curtain walling frames, rainwater goods and profiled steel sheet are all routinely overcoated where the existing finish is still adhering well.

Warning signs that point towards replacement, in whole or in part:

• Perforation and through-corrosion. If the sheet has rusted through, or red rust is spreading outward from fixing points across the face, you have a substrate problem. Coating it hides it temporarily.
• Delamination. A coating that has chalked is a surface condition you can prepare and overcoat. A coating peeling away in sheets is losing adhesion from the substrate, and it will take your new system with it.
• Cracked and crazed older plastisol-type finishes. Some heavily weathered coatings become unstable hosts for an overcoat and need specific primers or mechanical preparation. Coating manufacturers publish guidance on what can and cannot be overcoated, and a serious contractor will identify the existing finish rather than assume it.
• Cut-edge rust. Corrosion at exposed cut edges, typically along laps, eaves and gutter lines, is a separate scope item with its own treatment approach. Spraying over it changes nothing. Where it has undercut the coating extensively, edge or panel replacement may be the honest answer.
• Wet or failed insulation core in composite panels. If moisture has entered the panel, the finish is the least of the problem.
• Failed sealants, gaskets and flashings. These can often be renewed alongside a spray programme, but they need to be in the scope explicitly. They are not covered by coating.

In practice a great many commercial buildings sit in the middle: mostly sound cladding with a handful of damaged panels, some cut-edge rust at the eaves and tired sealants. The right answer there is a hybrid, replacing the failed panels and treating the edges, then spraying the envelope to a single consistent finish. Any contractor who looks at that building and proposes spraying alone has not surveyed it properly.

Before the specification is settled, expect adhesion testing and a sample area. A test patch shows how the existing coating responds to the proposed system and sets an agreed benchmark for the finish.

What in-situ spraying on an occupied building actually involves

The disruption argument in favour of spraying over re-cladding is genuine. It is not the same as no disruption.

Overspray management is the real operational constraint. Atomised coating travels on air movement. Protecting vehicles, neighbouring property, glazing, roof lights, plant intakes and stored goods requires exclusion zones, sheeting and cooperation from the occupier. Air handling intakes near a working elevation may need temporary isolation, which means facilities involvement rather than a note in a method statement. Car parks in the working zone need clearing, and somebody has to own telling staff and visitors where to park instead.

Weather governs the programme. Coatings have stated application windows for air temperature, substrate temperature, relative humidity and dew point, plus a practical limit on wind speed for overspray control. Rain stops work. In the UK, usable spraying conditions are considerably more generous between spring and early autumn than in the depths of winter, and a programme that ignores this is a programme that will slip. A credible plan carries weather contingency rather than pretending it away.

Phasing follows your operation, not the contractor’s convenience. Sequencing by elevation, working around delivery bays and shift patterns, and agreeing daily access windows in advance are all reasonable asks. Out-of-hours and weekend working is often the right call for retail and distribution sites, but it costs more, and night work loses daylight, which matters for finish inspection. On a live yard, ask to see risk assessments and method statements written for your site rather than a generic template.

Realistic duration depends on area, number of access moves, number of coats and the recoat intervals the system requires, all moderated by weather. A single modest elevation is typically a matter of days. A full multi-elevation industrial or retail unit is normally measured in weeks. Ask for a phasing plan showing which zone is affected when, with named contacts on both sides.

What the warranty is actually contingent on

A warranty figure on its own tells you very little. What matters is the list of conditions attached to it, because that list is where the work quality is defined.

Coating warranties typically depend on some combination of the following:

• Applicator status. Many manufacturer-backed warranties are only available through applicators approved by that manufacturer for that system.
• Preparation to a stated standard. The cleaning, degreasing, abrading and priming regime is specified, not left to judgement, and it is usually the first thing examined if a claim arises.
• The correct primer for the identified existing coating. This is why coating identification matters. The wrong primer over the wrong finish is an adhesion failure waiting to happen, regardless of how good the topcoat is.
• Achieved dry film thickness. Systems specify a target thickness. Spraying thin is the easiest way to reduce material cost invisibly, and it is precisely what the warranty conditions exist to prevent. Readings should be taken and recorded.
• Application within environmental limits. Temperature, humidity and dew point conditions at the time of application, logged.
• Records. Batch numbers, adhesion test results, thickness readings, weather logs and photographic evidence by zone.
• Sometimes a maintenance regime. Periodic washing down is a common condition, particularly in coastal, industrial or heavily polluted locations.

Exclusions matter just as much: mechanical damage, substrate corrosion originating in areas you chose not to remediate, and cut edges left untreated at your instruction. Then ask who stands behind it. A manufacturer product warranty, a contractor workmanship guarantee and a jointly issued warranty are three different instruments, and a contractor guarantee is worth exactly as much as the contractor’s continued existence.

Questions to ask when two quotes do not match

If one price is materially lower, the difference is somewhere. These questions usually surface it.

1. What coating system, by manufacturer and product name, how many coats, and what target film thickness? A one-line description such as "spray applied finish" is not a specification.
2. How have you identified the existing coating, and will you carry out adhesion testing and a sample area before full application?
3. What preparation is included, in sequence? Wash only, or degrease, abrade, remove failed coating mechanically, spot prime and treat corrosion? Who inspects it and against what standard?
4. What is excluded? Panel replacement, cut-edge treatment, sealant and gasket renewal, rainwater goods, flashings and roof coatings are all common exclusions that reappear later as variations.
5. Is access included in the price or carried as a provisional sum? How many access moves are assumed?
6. What working pattern have you assumed, what changes if our operation requires different hours, and who carries weather delay risk?
7. What overspray protection is included, and what insurance is in place? Get the cover confirmed in writing.
8. Who issues the warranty, what are its conditions, and what records will I receive on completion?
9. Who is physically on site? Directly employed sprayers or subcontract labour, what supervision, and what evidence of accreditation and manufacturer approval can you provide?

A lower price is not automatically a worse one. Sometimes it reflects better access planning or a more efficient phasing approach. But if the answers to questions 1, 3 and 4 are vaguer on the cheaper quote, you are not comparing two prices for the same job. You are comparing two different jobs.

The honest summary

Metal cladding spraying is the right call on a building whose panels are sound, whose weathertightness is intact and whose finish has simply aged. There it is a strong commercial decision: a fraction of the capital cost of re-cladding, a fraction of the disruption, and a finish matched to a brand palette. It is the wrong call on an envelope that is failing, and only a partial answer on the common building that needs some replacement and remediation alongside the coating.

Finding out which you have takes a proper survey, an identified existing coating and a written specification that says plainly what is included and what is not. If you want that starting point, get a free quote from Chameleon and ask for the specification in writing, not just the number.