Technical White Paper 10 min read

ACP vs HPL vs Aluminium Composite: A Technical Comparison for Architects

The Cladding Decision: What Architects Need to Know

ACP, HPL, and solid aluminium composite all look similar at 50 metres. At the specification stage, they're profoundly different products. Fire performance, structural behaviour, UV resistance, and long-term cost of ownership vary significantly.

Material Properties Comparison

Fire Performance: The Critical Specification

This is where the materials diverge most significantly:

1.PE-Core ACP burns freely, produces toxic smoke. Not acceptable for external cladding above 10m per NBC 2016. Banned in UK post-Grenfell.
2.FR-Core ACP: self-extinguishing per ASTM E84 Class B1. Core must contain at least 90% inorganic content — verify with test certificate.
3.A2-Core ACP (mineral core): non-combustible mineral fill. Equivalent to HPL fire performance. Price premium: 60-80% over FR core.
4.HPL: fire rating depends on specific product — verify the specific test certificate, not just the brand.

Weathering and UV Performance

Long-term stability in Indian conditions:

1.PVDF (Kynar 500/Hylar 5000) coating on ACP: gold standard. Delta E colour change < 5 units over 10 years. Always specify PVDF, not polyester, for external ACP.
2.Polyester coating on ACP: acceptable for sheltered applications. Shows measurable chalking and fade within 5-7 years in direct sun.
3.HPL: phenolic resin matrix provides inherent UV stability.
4.For coastal installations within 5km of the sea: specify HPL or A2 ACP.

Fabrication Considerations

1.ACP can be routed and bent to virtually any shape — columns, curved facades, angled reveals. This is its primary design advantage over HPL.
2.HPL is rigid. Curved designs require factory-formed panels at significant premium.
3.ACP minimum bend radius: approximately 4× panel thickness.
4.CNC routing precision: ACP grooves must be cut to exactly the right depth (1.5× aluminium skin thickness). Under-routing causes cracking; over-routing weakens the panel.