What are edge restraints and edging kerbs?
Edge restraints (edging kerbs) are fixed perimeter borders installed around block paving to prevent lateral movement and keep blocks from spreading or shifting.
Block paving sits on a base of sand and aggregate, which can shift and compact unevenly under load and weather exposure. Without physical containment, blocks at the perimeter of a paved area gradually creep outward, creating gaps, uneven surfaces, and eventual failure of the installation. Edge restraints (also called edging kerbs or haunching) form a fixed boundary that stops this lateral movement.
These restraints typically take the form of concrete kerbs, steel edges, or aluminium channels set along the perimeter of the paving. They are bedded into the sub-base or foundation layer and sit flush with or slightly proud of the block surface. The haunching (backing material) around the kerb prevents blocks from rocking and transfers their weight downward rather than outward.
Edge restraints are essential for durability. Without them, a paved drive or patio will eventually show signs of distress: loose blocks, trips and dips at the edges, and an overall loss of structural integrity. They are particularly important in areas with freeze-thaw cycles, heavy foot traffic, or where vehicles cross the edge of the paved area. When commissioning new block paving, specifying adequate edge restraints is a core part of ensuring the work lasts.