CovaMetal 20

A reflective coating for a metal roof combines three technical mechanisms on the same substrate:

• Anti-corrosion protection: an anti-oxidation primer and an insulating resin that cut off the metal’s contact with oxygen and moisture, which cause rust.
• Solar reflectance: reflects up to 90% of solar radiation rather than letting it heat the roof. On a metal roof, this effect is particularly pronounced because metal is an excellent thermal conductor.
• 200% elasticity: the elastomeric resin forms a film that absorbs differential expansion between steel deck sheets and seals the sheet overlaps, where 80% of leaks are concentrated.

The anti-UV Top Coat completes the system. It protects the resin from ultraviolet rays, stabilizes the whiteness, and prevents chalking over twenty years.

CovaMetal 20 is the reflective steel-deck coating suited to the following situations:

• Superficial corrosion of the sheets, localized or extensive but not through-going
• Worn sheet overlaps with micro-leaks
• Oxidized fastening points (screws, rivets) that create infiltration points
• Aging metal ridges and edges
• Steel deck roofs more than 10 years old that overheat in summer

For a structurally sound metal roof that needs only the reflective effect, the pure reflective coating CovaTherm may be enough. For a perforated steel deck or a degraded load-bearing structure, though, you still need a partial or full replacement before application.

A professionally applied reflective steel-deck coating typically runs between €20 and €25/m², all-inclusive: assessment, mechanical stripping of corroded areas, plus supply and application of the complete system. Three factors cause the final figure to vary:

• The level of corrosion of the substrate, which determines the extent of the prior stripping and the localized reinforcements needed
• The area to be treated, with a sliding scale beyond 2,000 m²
• The complexity of the roof (overlaps, ridges, drains, penetrations)

Against the traditional alternative, the case is clear-cut:

• Full steel deck replacement: €80 to €120/m² with removal, plus the associated business shutdown
• CovaMetal 20 (3-in-1 reflective coating): €20 to €25/m²

CovaMetal 20 cuts the renovation budget by a factor of 4 to 5, with the reflective effect and a twenty-year warranty thrown in. You can estimate the savings of a reflective steel-deck coating on your building.

A steel deck renovation unfolds in five controlled steps, carried out by a professional applicator you commission.

1. Technical assessment. A technician evaluates the condition of the sheets, locates the corrosion areas, identifies the sheet overlaps and fastening points to be reinforced, and checks the load-bearing capacity of the structure. A poorly assessed substrate means a coating that blisters or delivers neither anti-corrosion nor waterproofing.
2. Mechanical stripping. The corroded areas are mechanically brushed to remove loose rust and recover sound metal before treatment. The sound sheets are cleaned with a high-pressure washer.
3. Application of the anti-corrosion Base Coat. A first coat treats the metal in depth and blocks the progression of oxidation. The sheet overlaps and fastening points receive a localized reinforcement.
4. Application of the reflective elastomeric resin. The Base Coat is sprayed from the ground, at 400 to 800 g/m² depending on the level of corrosion and the roughness of the substrate. The machines stay at the foot of the building; only the hoses go up to the roof.
5. Application of the Top Coat. The anti-UV finish seals the system and guarantees reflectivity over two decades.

Application is done in dry weather, between 10 and 35°C. A typical 1,000 m² project is completed in 3 to 5 days, with no downtime for the building’s operations. Leave the application to a professional applicator trained to work safely on metal roofs.

On a dark steel-deck roof, the surface can hit 70 to 80°C in midsummer. That heat speeds up the breakdown of the sheets in three ways: faster oxidation when moisture hits hot metal (nighttime dew), thermal expansion that unseals the sheet overlaps, and repeated expansion-contraction cycles that fatigue the fastening points. Research on the aging of roof coatings is clear that ultraviolet light and thermal cycles are the two main degradation factors, and the process is highly temperature-dependent (Miller, Kriner & Desjarlais, 2002).

By taking the heat out of the roof surface, the reflective steel-deck coating sharply limits all three factors. Field tests run by the Lawrence Berkeley National Laboratory measured a surface temperature drop from 79°C to 49°C after a reflective coating was applied (Akbari, Berdahl, Levinson et al., 2005). Less heat absorbed means less differential expansion, fewer nighttime oxidation cycles, and a steel-deck service life extended by 8 to 10 years.

Beyond the direct benefits for the building, a reflective steel-deck coating helps cut the urban heat island effect, where city centers and industrial zones run on average 2 to 10°C hotter than the countryside around them. The dark metal roofs of warehouses and industrial buildings are a big part of the problem, soaking up solar radiation and releasing it as heat.

Research on urban cooling strategies shows that widespread use of reflective roofs across a city could help lower ambient temperature and, in turn, the energy demand for air conditioning (Santamouris, 2014). Studies at the urban scale have even estimated that rolling out reflective roofs could cut heatwave-related mortality by 18%. Coating an industrial or logistics steel-deck building with CovaMetal 20 means pitching in on that collective effort, on top of gaining indoor comfort.