Self Cleaning Aluzinc PPGL Steel Coil for Roof Cladding Panels

Self Cleaning Aluzinc PPGL Steel Coil for Roof Cladding Panels

Dust on a roof is not only a cosmetic problem. Deposits hold moisture against the coating, feed biological growth and create a gradient that eventually shows as streaking down the panel face. A self cleaning top coat reduces that by lowering surface energy, so rain sheets off and carries loose dirt with it instead of leaving it bound to the film.

This coil is built on an aluzinc substrate for the corrosion side of the problem and a hydrophilic self cleaning top coat for the appearance side. It is a good match for large low slope roofs on industrial buildings, where access for cleaning is expensive and rain is the only maintenance a building owner will actually pay for.

Specification

How the Surface Works

• Low contact angle lets water spread and sheet rather than bead and hold dust.
• Dirt releases with rainfall instead of needing scheduled washing.
• Aluzinc substrate protects cut edges where water collects at laps.
• Reduced biological growth limits the dark streaking common on north faces.
• Suits low slope roofs where water moves slowly and deposits settle.

Recommended Roofs

• Large industrial and logistics roofs with limited access
• Low slope roofs in dusty or agricultural areas
• Buildings near trees where organic debris accumulates
• Public buildings where appearance is part of the brief

Buyer Questions

Does self cleaning mean no maintenance at all?

No. It reduces how often a roof needs washing, but gutters still block and fixings still need inspection. In heavy industrial atmospheres with oily deposits, rain alone will not remove everything.

What is the contact angle figure for?

It describes how water behaves on the surface. A lower angle means water spreads and sheets, which is what carries dirt away. Measurements are taken on the finished coating, not on a laboratory film.

Can the top coat be repaired on site?

Small scratches can be touched up with a compatible repair paint. On a self cleaning surface the repair area will behave differently for a while, so keep repairs small and out of the main sight line.

Is the coating suitable for vertical walls?

Yes, but self cleaning matters less on walls because rain washes them less effectively. On walls we usually recommend the standard weather resistant system instead.

Packing and Handling

Coils are wrapped in PVC film with paper interleaving, strapped on wooden pallets and labelled with heat number, coating batch and contact angle reading. Avoid stacking coils directly on the ground at site, since moisture drawn up through a pallet will mark the outer wrap and eventually the outer lap of the coil.

Site Practice

On low slope roofs, debris collects in the pan rather than washing away, so the self cleaning benefit works best where the profile has adequate fall. Check the minimum recommended pitch for the profile before ordering, because a roof that ponds water will hold dirt regardless of the coating.

The substrate is Aluzinc AZ100 - AZ150. The AZ designation describes the aluminium-zinc alloy coating weight, which is what gives cut edges and drilled holes their sacrificial protection. A higher coating weight extends time to red rust, but it also changes forming behaviour, so the grade should be matched to the exposure class of the finished building.

Coating thickness matters more than coating brand in service: Top 22 - 28 micron, primer 5 micron. Below roughly 20 micron total build, UV exposure in strong sun starts to chalk the surface within a few years, and the colour drifts before the steel itself shows any problem.

Formability is specified as T bend 2T without cracking. This determines whether the strip can be roll formed and folded at the job site without cracking the coating over the bend radius, which is the most common cause of premature coating failure on roofing panels.