Leaking through bitumen-impregnated corrugated fibre cladding

With one particular product imported from the 1990s to the mid 2000s, there have been cases where the bitumen coating has been found to break down, leading to water reaching the cellulose fibres inside the material and subsequent product failure. If you have bitumen-impregnated roof or wall cladding that was installed in this period, we recommend you inspect it closely at least once a year.

 

Causes

Paint failure

Missing flashings

Junctions with other claddings and/or roof poorly detailed/constructed 

Minimal jamb flange cover of aluminium windows

Listed under: Exterior, finishes, metal, aluminium, paint, balconies, cladding, flashings, parapets, walls, moisture, leaks, wall cladding, bitumen-impregnated corrugated fibre

Cause

Paint failure

Repair

  • if water entry through the cladding is suspected, engage a building surveyor to investigate and report
  • where degredation is minor and limited to the surface of the cladding, coating with 2 coats of good quality acrylic paint may be at least a temporary solution, but ask the cladding supplier for their advice first. Solvent-based paints should not be used
  • where the cladding has failed and leaks are confirmed, it should be replaced without delay. If it has proved durable for at least 15 years, it can be replaced with a comparable lightweight cladding product without a building consent. If it has not lasted 15 years, a building consent will be required for its replacement
  • where the cladding has not given satisfactory performance for 15 years, contact the original supplier/installer

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Cause

Missing flashings

Repair

  • as for the first repair

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Cause

Junctions with other claddings and/or roof poorly detailed/constructed 

Repair

  • as for the first repair

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Cause

Minimal jamb flange cover of aluminium windows

Repair

  • as for the first repair

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