Case 1

Good Practices

Design

Material selection for metal cladding should be based on aesthetics, cost, availability, formability and corrosion resistance in accordance with BS 5427, and structural performance and fire safety. Evaluation of corrosion resistance of the metal should be based on product warranty, environmental effects (external, internal, industrial, and acid rain), and maintenance (unwashed areas). Aluminium infill panels should be based on BS EN 485-1 or equivalent. Mild steel infill panels should be adopted in accordance with BS EN 10346 or equivalent.

Fabrication

For enamel panels, baking of the panels should be performed once each for primer coat, second coat and finish coat. Baking can be performed more frequently depending on the surface finishing conditions. The panels should be baked at 810 to 840 0C for primer coat and 780 to 820 0C for second and finish coats. The manufacturing process should be strictly adhered to since it affects the durability of the panels. The suggested thickness of the enamel layer are:

Primer coat: 80 to 100 microns
Second and finish coats: over 100 to 140 microns
In case of stipple finish, the finish thickness will be about 500 microns.

Construction

Ensure the use of the manufacturer’s fasteners/brackets/stiffeners and all fixings and accessories to prevent sacrificial corrosion, as well as transmit all imposed loads and stresses of the cladding. Avoid scratching and damage of protective coating/film during site handling and installation. Alert designer/supplier if cladding is exposed to high concentrations of sulphur and chloride containing gases. Refer to lightning protection in accordance with SS 555-1 to 4. Remove drill swarf and other visible contaminants from the cladding surface to avoid corrosion.