What Is a Non-Climbable Zone (NCZ) on a Pool Fence?

What is the non-climbable zone?

The non-climbable zone (NCZ) is the area around your pool fence that must be kept clear of anything a child could use to climb over. It takes the shape of a quarter-circle arc - 900 millimetres in radius - measured from the top of the fence outward and downward on the approach side.

The logic is straightforward: a fence that is 1.2 metres high provides little protection if a child can stand on a pot plant or pool pump cover beside it to reach the top. The NCZ requirement removes that possibility.

Why does it matter so much?

Young children are resourceful and surprisingly capable climbers. Items that adults see as completely unrelated to the pool - a garden bed, a recycling bin, a fold-out chair left nearby - can serve as a stepping stone. The NCZ requirement is specifically designed to prevent this by defining a clear zone that must remain free of any climbable object at all times.

It is consistently one of the most common reasons pools fail compliance inspections in Australia. The fence itself is often perfectly fine - it's what's around it that causes the failure.

The two zones you need to know

Outside the fence (approach side)

A 900mm arc measured from the top of the fence outward and downward must be clear. This is the zone a child would be in before attempting to climb. Nothing within this arc should offer a foothold, handhold, or boost.

Inside the fence (pool side)

A 300mm zone measured from the top of the fence on the inside must also be clear. This prevents a child from using something on the pool side to help them descend once they've reached the top.

Boundary fences - different rules apply

If your pool uses a boundary (dividing) fence as part of its barrier, the rules are different. The fence must be at least 1.8 metres high, and the 900mm non-climbable zone applies on the inside (pool side) only - not the outside. However, horizontal rails on a boundary fence must be spaced at least 900mm apart to prevent them from acting as a ladder from the neighbour's side.

What must be kept out of the NCZ?

Any object that could help a child reach the top of the fence must be removed or relocated. Common items that cause NCZ failures:

• Garden beds, raised planters, and pot plants
• Trees and shrubs - including branches overhanging from a neighbouring property
• Pool equipment: pumps, filter housings, heat pump units, filter boxes
• Outdoor furniture: chairs, tables, sun lounges, ottomans
• BBQs and storage containers
• Children's toys, bikes, and scooters
• Deck ledges, window sills, and steps
• Retaining walls or garden edging that raises the ground level near the fence

The most common NCZ failures at inspection

Based on patterns seen across thousands of pool inspections in Australia, these are the most frequent issues:

• Garden growth: A plant that was well clear of the fence when it was first inspected has grown into the zone. This is the single most common failure. Regular trimming is essential.
• Pool equipment proximity: The pump or filter was installed close to the fence and has never been flagged because the pool was never inspected. Many older pools have this issue.
• Neighbour's overhanging branches: The owner assumes it's the neighbour's problem. Legally, it is the pool owner's responsibility.
• Raised garden beds added after installation: A renovation has inadvertently raised the effective ground level next to the fence, reducing the functional height of the barrier.
• Horizontal rails on boundary fences: Installed too closely together, they create a built-in climbing ladder on the approach side.

What to do if your NCZ is not clear

The fix depends on what's causing the problem:

• Pot plants and garden beds: Move them away from the fence or remove them entirely.
• Trees and shrubs: Trim back to beyond the 900mm arc. For large trees, you may need an arborist.
• Pool equipment: Relocate to a position that falls outside the NCZ. A plumber or pool technician can do this work.
• Permanent structures: Retaining walls or raised decking that sits within the zone may require modification to the fence or the structure itself. A licensed builder or fencer can assess the options.

If you're not sure what's failing, a pool inspector can walk through the NCZ with you before an official inspection and tell you exactly what needs to change. This avoids paying for a re-inspection after a failed first attempt.

The 2024 Australian Standard update on NCZ plants

The 2024 revision of AS 1926.1 added a dedicated section specifically addressing plants within the non-climbable zone. This reflects just how persistently common the issue is across Australia. The 2024 version provides clearer guidance on how to assess and manage plant growth near pool barriers - something that was underspecified in earlier editions.