Parapet Cappings

Cappings are flashings used to cover the top of a parapet wall to protect the wall from the ingress of moisture. Instead of chasing into the wall and using step flashings, the preferred detail is to cover the inside of the parapet wall with vertical ribbed metal or other cladding material, used in conjunction with an apron flashing. (See Vertical Cladding (Parapet Flashing and Detail).

Capping corners and expansion joints located at the corners must be sealed within 2 m from each direction of the corner measured on the interior side.

The corner of the wall is a fixed point for the capping, and as thermal movement can only occur in one direction away from the corner, an expansion joint should be provided as shown.


Parapet Corner Capping

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A slope is required to drain water from the top surface and avoid ponding

Parapet cappings must have a positive slope of 5˚ onto the roof side, but parapet cappings that follow the slope of the roof do not require any fall across its width. Parapet cappings wider than 300 mm can fall both ways, with the 5˚ drainage angle provided on both sides.

Cappings must not be fixed to the structure through the top of the capping, but can be fixed on the vertical leg by one of three methods. (see drawing 5.3.4. B, C, & D).

  1. A continuous cleat is fastened on the exterior face of the wall with an open hem at the drip for ease of application. After the exterior face of the capping is hooked to the cleat, the capping on the interior side is secured to the parapet using washered fasteners through oversized holes.
  2. Intermittent clips are fastened to the exterior face of the wall at 600 mm centres. All cleats and clips should be accurately aligned and clinched after fixing, while still allowing for expansion without chatter or vibration.
  3. The capping is fastened to the parapet on both sides using screws with sealing washers through oversized holes.




Revision Category: 
2 - Editing and rearrangement
Revision Detail: 

Completely revised clause.

Draft Clause: