Roofs in 55% Al-Zn metallic coated steel can provide a trouble free life of more than 30 years, provided correct design and fixing practices are followed, and correct maintenance procedures carried out.

55% Al-Zn is easy to fix and can withstand robust site handling, but if it is to provide the best possible life the following guidelines should be followed to optimise performance. Further guidance can be obtained from your profile supplier.

STORAGE

• Sheets must be kept dry to avoid storage corrosion, which is both unsightly and can result in reduced corrosion protection at affected points.
  
  
• Storage should preferably be indoors in clean, dry areas.
  
  
• If sheet stacks cannot be kept indoors:
  
  1. Erect a simple scaffolding and cover with a waterproof material. Leave space between the cover and the sheet stack to allow air to circulate.
     
  2. Store off the ground and on an angle, so any water which penetrates the cover can drain away quickly.
     
  3. Check the storage site regularly for water penetration.
     

SURFACE PROTECTION

• If any material is used as protection during installation or maintenance, it must be removed as soon as work is completed, so the risk of corrosion can be prevented.
  
  
• Available with clear acrylic protection against foot or handprints.
  
  
• All swarf and installation debris must be completely removed on completion of installation. All surfaces should be cleared and left clean.
  

INCOMPATIBLE MATERIALS

• Do not use with copper or lead. Water run-off from pipes, channels or fixings containing copper or lead should be avoided, as should contact with wet timber, concrete or mortar. For optimum performance all accessories should be made from 55% Al-Zn.
  

INCOMPATIBLE ENVIRONMENTS

• 55% Al-Zn is not suitable for use in alkaline rich environments, and its use should be avoided in, for example, agricultural buildings for animal housing or organic fertiliser storage.

MARKING OF SHEETS

• Do not use black lead pencil. Use other colours and clean off as soon as possible. Take care not to damage the coating by metal marking or the careless use of installation tools.

CUTTING

• Wherever possible use factory-supplied cut lengths. Alternatively, use power saws and nibblers. Do not use grinding wheels or cutting discs. Cutting with an abrasive disc or hacksaw, or burning through with oxyacetylene or similar torches should always be avoided. Avoid swarf deposits or drill chips on fixed panels.

SEAMING

• Make sure that damage to sheets is minimised by any on-site seaming techniques and machinery.

FASTENERS

• Poor quality fasteners will cause premature corrosion. To assure good performance, fastners should be made from 55% Al-Zn steel, or from stainless or heavy zinc coated steel. Consult your profile supplier for precise recommendations.

SEALANTS

• 55% Al-Zn is compatible with most sealants, but neutral cure silicone sealants are to be preferred.

BRAZING AND SOLDERING

• Not recommended.