A storefront ACP fascia in Karnataka has to survive a monsoon, a summer, and the next vendor's mistakes. The single biggest factor in whether it does that is the gauge of the aluminium skin on the panel — and almost no buyer asks about it.
ACP (aluminium composite panel) is a sandwich: aluminium skin, polyethylene core, aluminium skin. The 'skin' thickness, measured in millimetres, decides almost everything. The core thickness — usually 3 mm — barely changes between brands.
**0.30 mm skin** is the international premium grade. Mostly imported. You'll see this on bank fascias and large hospitality groups. Holds shape forever, paint film doesn't crack, but procurement teams flinch at the price.
**0.21 mm skin** is the honest minimum for an outdoor fascia in a coastal-monsoon climate. Domestic A-grade brands ship this. It's what we spec on every install unless the buyer has a reason for something else.
**0.18 mm skin** is what most lowest-bid quotes quietly substitute. The panel looks identical for the first 18 months. Then the skin starts denting under thermal expansion, the paint begins hairline cracking at the bend radii, and the fascia looks tired five years before it should.
**0.10 mm skin** exists. Don't use it outdoors. Use it for an internal cladding panel where nothing touches it.
When you're comparing quotes, the ACP line item is where the savings hide. A 100 sq.ft fascia at 0.18 mm versus 0.21 mm saves the vendor about ₹3,500 in raw material — and they can pass two-thirds of that on to look competitive. Five years later you're spending ₹40,000 on a refit because the original fascia rotted at the bend lines.
The spec to put on every signage RFQ: "ACP panels: minimum 0.21 mm aluminium skin both sides, A-grade brand, written warranty against delamination and paint cracking for minimum 5 years." If the vendor objects, you've found out something about them.
