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Confined space

A confined space is an enclosed area not designed for human occupancy with restricted entry and possible harmful atmosphere. WHS Reg Ch 4 Part 4.3 + AS 2865 apply.

By Chalkline. Last updated 14 May 2026. Verified 14 May 2026.

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A confined space under the model Work Health and Safety Regulation Chapter 4 Part 4.3 is an enclosed or partially enclosed space that:

  • Is not designed or intended primarily for human occupancy.
  • Has restricted means of entry and exit.
  • Is at atmospheric pressure during occupancy.
  • Is or is likely to be a risk to health and safety due to an unsafe atmosphere (oxygen below 19.5%, oxygen above 23.5%, contaminant above the workplace exposure standard, or a contaminant likely to cause impairment).

All four criteria must apply for the space to be a confined space in the regulatory sense. A small storage cupboard that is “tight” but ventilated is not a confined space; a subfloor void with a known sewer leak is.

Construction-site examples:

  • Subfloor voids with poor ventilation, especially after recent waterproofing or sealant work.
  • Sumps and pits (stormwater, sewer rising-main, lift pits).
  • Water tanks, septic tanks, grease traps during install or inspection.
  • Ducts and chimneys during inspection or remediation.
  • Roof spaces where access is restricted and ventilation has been blocked.
  • Pre-cast wall panels with internal cavities at lift and place stage.

Required controls (in order):

  1. Eliminate the need to enter (do the work from outside, use a robot, remove the lid completely).
  2. Risk assessment by a competent person before entry.
  3. Atmospheric testing by calibrated 4-gas meter (O2, CO, H2S, LEL) before entry and continuously during occupancy.
  4. Permit-to-enter signed by the person with management or control before each entry.
  5. Stand-by person outside the space, with line-of-sight or two-way communication, who does not enter.
  6. Rescue plan ready before entry, with retrieval lines and equipment on hand.
  7. Confined-space training for every entrant and stand-by person.

Permit-to-enter is not a generic safety form. It is a specific document under Part 4.3 listing the space, the entry time window, the testing results, the entrants, and the controls.

HRCW status. Confined-space entry is High Risk Construction Work under WHS regulations, triggering the mandatory SWMS requirement in addition to the Part 4.3 controls.

For builders. Most residential builds will not have a true confined space on site. Two common false-positives:

  • A tight subfloor with normal ventilation is not a confined space, just tight access.
  • A roof space that is enclosed but well-ventilated and oxygen-normal is not a confined space.

When the four criteria do all apply, stop work and engage a confined-space competent person. Untrained entry is a Category 1 or 2 WHS offence waiting to happen.

Also known as: restricted-entry space, permit space.

Category: WHS / HRCW / confined spaces.

See also

Last updated: 2026-05-14. Verified: 2026-05-14.

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