Compatibility with other materials

Compatibility with other materials is also an important consideration, particularly when using aluminium.

Aluminium is particularly susceptible to electrolytic corrosion with dissimilar materials. With an organic coating, it is liable to attack if pierced or cut, and anodized aluminium is as susceptible as the

5.24 Examples of self-tapping screws: (a) 12 point plastic head type 'Z' cone-pointed screw with sealing ring to BS 1494 Part I 17; (b) modified version of (a) with load-spreading head; (c) modified version of (b) with spacing collar; (d) self-drilling screw.

untreated metal.There is no corrosive action between aluminium and zinc or between zinc coatings and galvanizing.

Aluminium sheeting, whether organically coated or not, suffers attack from many building materials. Direct contact should be avoided by good detailing and efficient drainage to prevent water run-off If unavoidable,the protective measures listed inTable 5.3 can be taken.

Hot-dip zinc-coated steel suffers moderate attack from copper alloys, iron, steel, some timbers, cement, concrete, plaster, asbestos cement, copper-bearing paints and stainless steel, particularly if water run-off from material onto this cladding occurs. Direct contact should be avoided by good detailing, and efficient drainage will prevent run-off

Rivet in drilled hole Rivet after drawing before drawing and stem snapped

Rivet in drilled hole Rivet after drawing before drawing and stem snapped

5.25 Rivets for secondary fixings in metal cladding: (a) pop rivet; (b) sealed-end rivet.

5.25 Rivets for secondary fixings in metal cladding: (a) pop rivet; (b) sealed-end rivet.

Organic coatings on hot-dip zinc-coated steel are unaffected by all common building materials, unless they are cut or pierced, when they behave similarly to hot-dip zinc-coated sheet.

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