Does a retaining wall need building consent?

Two clauses of Schedule 1 cover retaining walls.

Schedule 1 of the Building Act lists the work that needs no building consent. Two of its clauses are about retaining walls: one anyone may use, by the depth of ground the wall holds and what sits above it, and one for a rural zone, where a chartered professional engineer designs or reviews the wall.

• Every exemption, on one page

The depth of ground it holds, and nothing on top.

MBIE's examples: rebuilding an earthquake-damaged timber wall < 1.5 m high with nothing on it, and terracing a slope with 1.2 m crib walls set far enough apart that none loads the one below, need no consent. A wall 0.9–1.8 m high needs one for the part > 1.5 m.

Building Act 2004 Schedule 1 clause 20 · MBIE, exempt building work guidance 13.2

Any of these takes the wall out of the exemption.

Clause 20 exempts a wall that carries the ground it holds and nothing more. MBIE's example: a 1.2 m wall below a neighbour's driveway needs a consent, because the driveway loads it.

Building Act 2004 Schedule 1 clause 20(b) · MBIE, exempt building work guidance 13.2

On a farm, a wall that fails is less likely to hurt anyone.

MBIE's examples: a 2.5 m wall 3 m from a house, designed by a CPEng, needs no consent. A 3 m wall 1 m from a house needs one, being closer than its own height, and so does a wall designed by an engineer who is not a CPEng.

Building Act 2004 Schedule 1 clause 41 · MBIE, exempt building work guidance 13.3

A wall 1.5 m high is a 1.5 m fall.

MBIE notes that a retaining wall with a fall of ≥ 1 m off it may need a safety barrier under F4, weighing what the wall is for, how easily people reach it and whether young children are about. The barrier does not make the wall need a consent.

Building Act 2004 ss 14B, 17 · NZBC F4.3.1 · MBIE, exempt building work guidance 13.2 and 13.3

• F4: safety from falling
• What still applies to exempt work