Prokol TopSpray35: Complete Guide to Metal Roof Recoating

Prokol TopSpray35 is a spray-applied roof recoating system used to refurbish ageing metal roofs without the cost and disruption of full replacement. For many UK industrial units, garages and agricultural buildings, it can restore waterproofing, seal laps and fixings, and extend service life when the roof is still structurally sound. A successful Prokol TopSpray35 project depends on correct inspection, corrosion treatment, cleaning, priming where specified, and application in suitable weather conditions. Contractors should follow the latest manufacturer data and UK site safety rules, while homeowners should check whether leaks, condensation or failed sheets need repair before recoating.

What is Prokol TopSpray35 and when should you use it?

Prokol TopSpray35 is designed for roof refurbishment where a metal roof is weathered, leaking at details, or showing early corrosion, but does not yet need full replacement. In practical terms, it is often chosen for profiled steel roofs, industrial units, workshops, retail premises, outbuildings and garages where owners want to avoid a disruptive strip-and-replace project.

The key point is suitability. Recoating works best when the substrate remains fundamentally sound. If sheets are badly perforated, insulation is saturated, fixings have failed extensively, or there are structural movement issues, a coating system alone will not solve the problem. In those cases, localised repair or partial replacement may need to come first.

For UK buildings, recoating is especially attractive because metal roofs take a lot of punishment: driving rain, standing water on low-pitch areas, freeze-thaw cycles, UV exposure, and wind-driven ingress around laps and penetrations.

Why Prokol TopSpray35 suits UK metal roofs

A good metal roof coating must do more than look tidy. It needs to create a continuous waterproof barrier over sheet laps, fixings and awkward details, while coping with thermal movement. Metal roofs expand and contract noticeably, particularly on larger spans, so flexibility matters.

This is where Prokol TopSpray35 can be a strong refurbishment option. When specified and applied correctly, it helps create a seamless waterproof finish that reduces the number of vulnerable joints compared with patch repairs alone. That can be particularly valuable on older roofs where historic repairs have left multiple weak points.

UK compliance also matters. On refurbishment projects, contractors should consider:

• The Working at Height Regulations 2005 for safe access, edge protection and fall prevention
• COSHH requirements for handling coatings, cleaners and primers
• Building Regulations Part C where resistance to moisture is relevant
• Building Regulations Part L if wider roof upgrades affect thermal performance
• BS EN ISO 12944 principles where corrosion protection of steel is part of the specification
• BS 5250 where condensation risk needs assessment during refurbishment

At Forti Nova, we often advise customers at our Blackburn depot and showroom that the coating is only one part of the system. The right preparation, detailing and compatible products make the difference between a short-term fix and a durable refurbishment.

How to prepare a metal roof before using Prokol TopSpray35

Preparation is the stage most likely to determine success or failure. Even the best coating will struggle if it is applied over dirt, active rust, loose material or wet contamination.

1. Inspect the roof properly

Start with a full condition survey. Check sheet integrity, cut-edge corrosion, side and end laps, fixings, rooflights, gutters, penetrations and previous repair areas. Note any signs of trapped moisture or internal condensation. If the roof deck or supporting structure is compromised, bring in a qualified roofing contractor or surveyor before recoating.

2. Deal with corrosion and failed details

Surface rust, cut-edge corrosion and failed fixings need attention before the coating goes on. Loose fixings may need replacing, badly corroded sections may require repair, and vulnerable details should be reinforced in line with the manufacturer specification.

3. Clean thoroughly

Metal roofs usually need a deep clean to remove dirt, chalking, biological growth and grease. Pressure washing is common, but the roof must then be allowed to dry fully. Any residual contamination can affect adhesion.

4. Prime where specified

Not every roof substrate is the same. Galvanised steel, coated metal, weathered surfaces and repaired sections may require different primers or local treatment. Always follow the latest Prokol technical guidance for the exact roof build-up.

How to apply Prokol TopSpray35 on a metal roof

Application should be carried out strictly to the latest manufacturer instructions and only in suitable site conditions. In the UK, weather windows matter. Avoid applying during rain, frost, surface dampness or temperatures outside the recommended range. Morning condensation on metal roofs is a common issue and can delay safe application.

Typical project stages include:

Detail work first

Critical points such as laps, upstands, penetrations, fixings and gutter interfaces are usually addressed before the main field area is coated. This helps strengthen the most leak-prone zones.

Main coating application

Prokol TopSpray35 is then applied across the prepared roof to achieve the required coverage and continuity. The goal is a uniform membrane with no missed areas, weak edges or poorly treated transitions.

Quality checks and curing

Once applied, the roof should be checked for film continuity, detailing quality and any areas requiring remedial work. Cure times depend on site conditions, so protection from traffic and adverse weather is important.

For contractors, the commercial advantage is speed and reduced disruption compared with full replacement. For homeowners, especially those tackling garage or outbuilding roofs, the key benefit is extending roof life without major invasive works.

Prokol TopSpray35 cost and lifespan considerations

The cost of a metal roof recoating project depends less on the product name and more on the roof condition. The biggest price drivers are usually:

• roof size and complexity
• access equipment and safety measures
• amount of rust treatment required
• number of penetrations, rooflights and gutters
• need for primers, reinforcement and detail work
• whether local sheet repairs are needed first

A straightforward, accessible roof in fair condition will usually cost less per square metre than a heavily corroded roof with multiple leaks and complex details. That is why site assessment matters.

In lifespan terms, recoating can offer excellent value when the substrate is still serviceable. However, it should not be sold as a cure for every failing roof. If the underlying roof has reached the end of its structural life, replacement may still be the right answer.

If you are unsure, visit the Forti Nova showroom in Blackburn. We can help you compare options, discuss compatibility, and point you towards the right waterproofing approach for your project.

FAQ: Prokol TopSpray35 for metal roof recoating

Can Prokol TopSpray35 be used on any metal roof?

No. It is best suited to metal roofs that are still structurally sound. If sheets are severely corroded, perforated or unstable, repairs or replacement may be needed first.

Is Prokol TopSpray35 better than replacing a roof?

It can be, if the existing roof is suitable for refurbishment. Recoating is usually less disruptive and more cost-effective than replacement, but it is not the right choice for every roof.

Can Prokol TopSpray35 be applied in winter?

Only if site conditions meet the manufacturer requirements. Rain, frost, low temperatures and surface condensation can all affect application, so winter work needs careful planning.

Need expert advice on Prokol TopSpray35 for a live job or upcoming refurbishment? Call Forti Nova on 01254 433987 or visit our Blackburn showroom for practical product guidance and waterproofing support.