Building Inspection and Preparation for Workers Post COVID

When buildings stand empty for extended periods, the risks that develop inside them are not always obvious until workers return. Extended vacancy during periods such as the COVID-19 pandemic created conditions that were unfamiliar to most facilities managers: HVAC systems that had been shut down or running at minimal capacity, water systems with stagnant water, and areas with elevated humidity that promoted mould and microbial growth. Preparing buildings for the return of workers requires a systematic inspection process grounded in the relevant Australian Standards.

Standards Australia's AS/NZS 3666 series directly addresses the risks of building systems that have been out of operation. Part 1 covers the design and installation of air-handling and water systems, but it is Part 2 and Part 3 that facilities managers need when bringing a building back into service: commissioning, operation, and maintenance requirements that include specific guidance for systems restarted after a period of non-use.

Key Risks in Buildings After Extended Vacancy

A building that has been closed or lightly occupied for weeks or months accumulates a specific set of risks. Understanding these risks is the foundation of an effective pre-return inspection programme:

Mould and Microbial Growth

Reduced ventilation combined with any residual humidity creates ideal conditions for mould. Mould growth can occur on walls, ceiling tiles, carpets, and within HVAC ductwork. Once established, mould colonies can continue to grow even after normal HVAC operation resumes if the source of moisture is not identified and eliminated. Inspectors should check all susceptible surfaces, particularly in bathrooms, kitchens, server rooms, and any areas adjacent to exterior walls or roofing.

Water System Risks

Stagnant water in building pipes is a primary risk factor for Legionella bacteria. When water sits in hot and warm water systems within the temperature range of 20 to 45 degrees Celsius, Legionella can multiply rapidly. Before occupants return, water systems must be flushed according to the protocols set out in AS/NZS 3666.2 and the AIRAH DA19 guideline. This includes all tap outlets, showerheads, cooling towers, and decorative water features.

Air Quality and HVAC Condition

HVAC systems that have operated at low capacity or have been fully shut down may have accumulated contamination in filters, drain pans, and ductwork. Before workers return, air handling units should be inspected for filter condition, coil cleanliness, drain pan integrity, and belt or fan condition. Ventilation rates should be verified against the design specifications for the occupancy level expected on return.

Corrosion and Structural Condition

In coastal locations or areas with high humidity, extended periods without regular inspection allow corrosion to advance on structural elements, pipe fittings, and electrical conduit. A building inspection before return should include checks of exposed metalwork, pipe connections, roof drainage, and any areas where water ingress may have occurred during the vacancy period.

Digital Inspection Checklists for Building Re-Entry

The breadth of a post-vacancy building inspection makes digital inspection tools particularly valuable. A paper checklist for building re-entry can run to dozens of items across multiple systems and locations. A digital inspection platform allows a facilities manager to build a structured checklist that guides inspectors through every required check in a logical sequence, with mandatory completion of each item before submission.

Photo evidence is critical in this context. When an inspector finds mould growth or a corroded fitting, a photo attached to the inspection record creates a dated, located record of the condition that supports the maintenance work order, documents the pre-remediation state, and demonstrates to building owners and insurers that the issue was identified and acted upon promptly.

What a Building Re-Entry Inspection Should Cover

• HVAC filter condition and replacement status
• Cooling tower inspection and water treatment verification
• Hot and cold water system flush records and temperature verification
• Mould and surface contamination check across all zones
• Roof and drainage inspection for water ingress during vacancy
• Fire safety system function test: sprinklers, detectors, extinguishers, emergency lighting
• Electrical switchboard and safety device inspection
• Lift and mechanical access equipment service records and certification
• Security and access control system test
• Sanitary facilities: flush all outlets, check plumbing, inspect for damage

For large or multi-tenancy buildings, the compliance and QA challenge is significant. Digital inspection systems allow the inspection to be divided across multiple inspectors working simultaneously, with a central dashboard showing completion status for each zone and system in real time.

Frequently Asked Questions

What does AS/NZS 3666 require when restarting building systems?

AS/NZS 3666.2 and 3666.3 require that air-handling and water systems be inspected and, where necessary, cleaned and disinfected before being returned to service after a period of shutdown. Water systems must be flushed to remove stagnant water and disinfected to control microbial risks including Legionella. Documentation of these activities is required and should include the date, method, persons responsible, and results of any microbial testing.

Who is responsible for building re-entry inspections?

The building owner or their appointed facilities manager carries the primary responsibility for ensuring a building is safe for occupation. In practice, this often means engaging specialist contractors for water system hygiene and HVAC commissioning, with a facilities manager coordinating the broader building inspection and using digital tools to track completion and document the outcomes.

How should mould found during a building inspection be handled?

Minor surface mould on non-porous materials can generally be cleaned in situ. Extensive mould growth, or mould within HVAC systems or structural cavities, requires professional remediation. The inspection record should document the extent and location of any mould found, the remediation action taken, and the post-remediation inspection confirmation that the issue has been resolved. A digital inspection record provides the complete chain of evidence for insurance and liability purposes.