Remediation details: parapets

Parapets were commonly detailed with a flat top and finished with the wall cladding material. The texture allowed water to sit on the surfaces, accelerating breakdown of the coating system and allowing water into the framing. Decisions about how to remediate parapets will depend on the amount of damage and the potential for failure in future.

Retaining and repairing parapets

Remedial work for parapets being retained will depend on the amount of damage. 

Flashing

Under E2/AS1, all parapets must be flashed, with a cap flashing having a 5° cross fall to prevent water accumulation. Where parapets are being retained, flashing the top is essential.

Where no structural damage has occurred and the cladding is sound, the parapet should be cap flashed as shown below.

Cladding removal and framing repair

Where the cladding has failed and there is framing damage, cladding removal and replacement of framing will be required.

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Removing parapets

If the cladding is being removed, this is a good time to decide whether the parapets should be kept or removed. Removal of a parapet will lower the building’s risk score and so may allow a direct-fix cladding to be retained (provided the timber framing is treated to a sufficient level).

Parapet removal involves modification to both the wall and roof.

Where the roof slope is parallel to the parapet or at right angles to the apex of the roof, the reconstruction detail after removing the parapet can be relatively simple by incorporating a cavity behind the cladding and flashing the top of the parapet. Using a wider flashing means that the roof cladding will not need to be altered but the flashing will need to be fully supported. Options for removing parapets are shown below.

Updated: 9 September 2014