The thinnest ACP cladding can be as little as 2 millimeters, but usually it is between 3 และ 4 millimeters for most uses. The choice depends on things like how big the panel is, what it’s made of, how much wind it will face, and the weather where it will be. If it’s a short building, 3mm might be enough, but tall buildings might need 4mm or even more, especially if the weather is really bad. It’s a good idea to talk to an expert to figure out the right thickness for a particular project.