How much concrete for kerb haunching per metre?

Concrete volume per metre depends on the kerb size. For HB2 kerbs (255mm high): approximately 0.03-0.04 m³/m including bedding and haunching both sides. For larger BN kerbs (305mm high): approximately 0.04-0.06 m³/m. The haunching profile is triangular at 45 degrees on both sides of the kerb.

What concrete mix for kerb bedding and haunching?

Kerb bedding uses a semi-dry mortar (6:1 or ST1 concrete) at 25mm depth. Haunching uses C20 (ST2) concrete for standard kerbs, or C30 (ST4) for heavy vehicle crossovers. The haunching must fully support the kerb face and extend from the base to at least half the kerb height, at a 45-degree angle.

What is the difference between bedding and haunching?

Bedding is the mortar or concrete layer the kerb sits on — typically 25mm deep, providing a level surface. Haunching is the concrete support on both sides of the kerb that holds it in position and prevents movement. Haunching is applied after the kerb is bedded and aligned. Both are essential for a stable kerb installation.

Do I need to haunch both sides of a kerb?

Best practice is to haunch both sides (front and rear). The rear haunch prevents the kerb being pushed forward by soil or vehicle pressure. The front haunch prevents the kerb falling forward into the road. For edging (flat top) where loads are light, a single rear haunch may suffice, but both sides is always recommended.

What backfill goes behind kerbs?

Behind the haunching, backfill with compacted Type 1 sub-base or the existing excavated material (if suitable). On driveways, the sub-base should be continuous behind the kerb. Leave the backfill 150mm below the top of the kerb to allow for the surface course. Compact in 100mm layers using a plate compactor.

TradeCalculator

Concrete Kerb Foundation Calculator — Haunching & Bedding

Calculate haunching profile, bedding depth, backfill and concrete volume per metre for kerb foundations.

Total Kerb Run

Kerb Type

125mm × 255mm

Concrete Price

How We Calculate This

This calculator determines the concrete volume for kerb bedding, front and rear haunching, and backfill based on kerb type and total run length.

Haunching profile

Haunch Volume = Length × Haunch Width × Kerb Height × 0.5
Triangular profile at 45° on both front and rear of the kerb. Bedding at 25mm depth under the full kerb width + 150mm.

Total concrete

Total = Bedding + Front Haunch + Rear Haunch
Expressed as m³ per linear metre of kerb run.

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Last updated: March 2026

All calculations are estimates. Verify with your supplier.