1/4" (6 mm) ACP / ACM strength summary
1/4 inch = 6 mm total panel thickness. This is a stiff, heavy-duty architectural grade ACP, much stiffer than standard 4 mm (0.16") facade panel, but strength depends far more on aluminium skin gauge (0.3 / 0.4 / 0.5 mm skins) than just total panel thickness.
Typical premium spec: 6 mm panel, 0.5 mm (0.020") 5005 alloy aluminium skins + PE / mineral core (the spec I'd use for exterior cladding) Weight: ~7.8 kg/m² (1.6 lb/sq ft)
Stiffness / span (most important for cladding)
6 mm premium ACP (0.5 mm skins): safe support spacing up to 1200 mm (48") between rails; 4 mm max ~750 mm
Relative flexural rigidity EI: roughly 2.5× stiffer than 4 mm ACP of the same skin thickness (Alucobond data: 5900 vs 2400 kN·cm²/m)Alucobond®
This means far less oil-canning / waving under wind load for large panels.
Core mechanical numbers (premium PE-core 6 mm ACP)
Tensile strength of the full panel: ~45–52 MPa
Flexural strength: ~100–140 MPa
Peel strength (skin-to-core bond): ≥4–7 N/mm (critical failure mode; cheap panels fail here first)
Impact: resistant to light knocks, hail (good for low-rise / coastal), but not impact-proof. A sharp heavy blow will dent the aluminium skin or delaminate the face from core.
What it is NOT strong at
Good: wind suction/pressure for rainscreen cladding, large flat cassettes, signage, column covers Not a structural load-bearing panel: do not use it to support dead loads, shelves, overhead weight Poor local puncture resistance: thin aluminium skins dent easily at point impact If skins are cheap thin 0.3 mm: stiffness drops a lot, even at 6 mm total thickness
Practical comparison
3 mm (1/8"): light sign grade, max span ~450 mm
4 mm: standard exterior facade, span ~750 mm (most common rainscreen)
6 mm (1/4"): heavy-duty, large-format cassettes, high wind zones, coastal exposure, where you want wide support spacing without stiffener ribs
Quick specification note for your supplier
If you order 1/4" ACP for facade, write:
6 mm total thickness, 0.5 mm 5005 alloy aluminium skins both sides, PVDF 70% Kynar 500 coating, minimum peel strength ≥5 N/mm, PE or A2 mineral core as required by fire code.
If you want, I can give you a simple deflection / wind load rule of thumb for your panel size and support layout.
