How to Install Wall Copings: Best Practices for Protection and Longevity
Copings are found on top of walls and can be made from various materials, such as natural stone, porcelain, brick, concrete, clay, or terracotta. They are often made bespoke for a project, or, more usually, the same paving material used on a patio or pathway.
Copings and pier caps are aesthetically pleasing whilst also essential for the structural integrity of walls and piers.
Structurally, copings are installed to protect the face of a wall from water damage. Importantly, they prevent water from reaching the cavity or centre of a wall, which causes deterioration in freeze-thaw cycles. Preventing water ingress also minimises the chance of leachates and efflorescence from discolouring the facework. Selected copings and pier caps should be frost resistant.
Correct coping installation is key to longevity, especially as they may have to take the weight of people sitting – even walking on them. They must be robust, able to withstand lateral and compressive pressures.
The general overhang of a coping is ideally a minimum 45mm. This can depend on the type of wall. For example, a scraped silicone-textured render finish to the vertical wall requires a minimum 50mm overhang to protect and prevent discolouration of the surface, which can be difficult to remove.
Copings should have a drip line/capillary groove installed to their underside, which is usually 5mm deep and 10mm to 20mm from the edge of the coping. Once the water runs off the edge of the coping, instead of carrying on to the wall, it hits the drip groove and drips to the ground. The groove should also pass through the jointing material, or you will get staining on the wall face between copings. I would also recommend that permeable jointing compounds should not be used.
Flat copings should have a fall to effectively direct water directly off the surface, ensuring that the water run-off is towards the rear of the main face of the wall.
A high-level damp-proof course should be installed beneath the coping. This protects the wall from water ingress, especially around joints.
Installation guidance may be found in British Standard BS7533:101, referencing certified bonding mortar/slurry primer to be applied to the top of the wall. Lay copings using a 1-3 OPC, to soft sand mortar mix, and apply bonding mortar to the underside of the coping with the inclusion of a DPC sandwiched between. This may be bitumen roll or a double course of slates, especially important under brick copings.
An exterior C2 S1 adhesive may be applied to a primed, dust-free, clean surface, free of and loose material on top of the wall and the underside ‘back buttering’ of the copings.
Copings require a waterproof ‘soft joint’ directly above, and vertically in-line with any expansion joints in the wall.
