Critical Risk Assessment NZ: 7 Critical Risks Every Builder Must Identify

Auditsure Ltd | Construction Health & Safety | September 2026

Every New Zealand builder has a responsibility to identify and manage construction health and safety risks that could seriously harm workers, subcontractors or members of the public.

But not every hazard presents the same level of risk.

A loose extension cord might cause someone to trip, while an unprotected roof edge could result in a fatal fall. Both require attention, but the consequences of something going wrong are very different.

This is why critical risk assessment is an essential part of construction health and safety in New Zealand.

A practical critical risk assessment helps builders identify activities that could cause death, permanent disability or serious occupational illness, establish effective critical controls and verify that those controls are working.

Whether you are building new homes in Auckland, renovating older properties in South Auckland or managing commercial construction projects across Waikato, understanding critical risks in construction helps protect your people and your business.

At Auditsure Ltd, we help builders and construction contractors improve their health and safety systems through critical risk assessments, construction site safety audits, Site Specific Safety Plans (SSSPs) and contractor safety management.

1. What is a critical risk in construction?

A critical risk is commonly understood as a work-related risk with the potential to cause a fatality, permanent disability or other severe harm.

In construction, critical risks can arise from working at height, operating mobile machinery, disturbing asbestos-containing materials, undertaking excavations or carrying out demolition work.

The key question for every builder is:

What could kill or seriously harm someone on this construction site, and what controls must be in place to prevent it?

For example, a worker may be exposed to two different hazards while undertaking roofing work.

Hazard	Potential consequence
Loose materials on the ground	Trip or fall causing injury
Unprotected roof edge	Fall resulting in death or permanent disability

Both hazards require suitable management. However, the fall from height warrants particular attention because of its potential consequences.

A construction critical risk assessment should focus on credible serious-harm scenarios rather than simply identifying every minor hazard.

Critical risk and New Zealand health and safety legislation

Under the Health and Safety at Work Act 2015 (HSWA), a Person Conducting a Business or Undertaking (PCBU) must ensure, so far as is reasonably practicable, the health and safety of workers and other people affected by its work.

For builders, this includes identifying foreseeable risks and implementing suitable measures to eliminate them or, where elimination is not reasonably practicable, minimise them.

New Zealand's health and safety reforms also introduce a formal statutory definition of critical risk from 1 April 2027. Builders should distinguish that definition from the broader critical-risk terminology already used in health and safety management systems.

For practical guidance, refer to WorkSafe New Zealand’s critical-risk information.

2. Seven critical risks every New Zealand builder should identify

The following seven categories should be considered during a construction risk assessment. They are not an exhaustive list: each building site must be assessed according to its actual work activities, environment and potential consequences.

Critical risk 1: Working at height

Working at height is one of the most significant serious-harm risks facing New Zealand builders and roofing contractors.

High-risk activities include:

• Roof installation and re-roofing.
• Working on scaffolding.
• Installing fascia boards and soffits.
• Working around unprotected floor openings.
• Using ladders and elevated work platforms.
• Working on fragile roofing materials.

A fall from a relatively low height can still cause fatal or permanent injuries.

Critical controls for working at height

Builders should assess suitable fall-prevention measures before work begins.

These may include correctly erected scaffolding, suitable edge protection, safe access systems and appropriately designed work platforms.

Where fall-arrest equipment is necessary, suitable anchorage, training, equipment inspection and effective rescue arrangements must also be considered.

A safety harness should not automatically be treated as a substitute for effective fall prevention.

Critical control verification: Before roofing work begins, the supervisor should check that the required edge protection and access arrangements are installed, suitable and effective.

Critical risk 2: Mobile plant and moving vehicles

Construction sites commonly involve excavators, trucks, forklifts, telehandlers and other mobile equipment.

When workers and moving machinery operate in the same area, there is potential for crushing, serious injury or fatality.

Examples include:

• Workers standing behind reversing trucks.
• Excavators operating near ground workers.
• Delivery vehicles entering active construction areas.
• Plant operating close to excavation edges.
• Workers entering machinery exclusion zones.

Critical controls for mobile plant

Establish suitable traffic management arrangements that separate pedestrians and machinery wherever reasonably practicable.

Use physical barriers, exclusion zones, designated pedestrian routes and suitable communication arrangements.

Ensure operators are competent and that plant is appropriate for the task and maintained.

Critical control verification: Check that separation arrangements remain effective as the site changes. High-visibility clothing alone does not prevent a person from being struck by machinery.

Critical risk 3: Asbestos exposure during renovation and demolition

Asbestos remains a significant occupational health risk for builders renovating older New Zealand properties.

Asbestos-containing materials may be present in:

• Fibre-cement roofing and wall cladding.
• Soffits and fascia materials.
• Vinyl flooring and backing.
• Textured coatings.
• Electrical switchboards and associated components.
• Insulation and other historical construction products.

Disturbing asbestos-containing materials can release airborne fibres that may contribute to serious diseases many years after exposure.

Critical controls for asbestos

Before renovation, demolition, drilling or cutting begins, builders should identify suspect asbestos-containing materials.

Arrange suitable asbestos surveys, sampling and laboratory testing where necessary.

Do not disturb suspect materials until the risk has been assessed and the appropriate work method established.

Use appropriately licensed asbestos removal contractors where required.

Critical control verification: Confirm the relevant asbestos information has been reviewed, the work method is suitable and any required removal documentation or clearance requirements have been addressed.

Critical risk 4: Excavation and trench collapse

Foundation construction, drainage installation and site preparation can expose builders to unstable ground.

A trench or excavation may collapse suddenly, burying or crushing workers.

Risks can increase following heavy rain, changes in ground conditions, additional loading near an excavation or disturbance from nearby machinery.

Critical controls for excavation work

Assess ground conditions before excavation begins.

Identify underground services and establish suitable excavation protection.

Depending on the circumstances, controls may include engineered shoring, trench shields, benching, battering or other suitable support.

Provide safe access and keep inappropriate loads away from excavation edges.

Critical control verification: A competent person should inspect excavation conditions and required controls, particularly after weather events or changes to the work.

Critical risk 5: Electrical contact

Builders regularly work around temporary electrical supplies, overhead power lines, underground cables and existing building wiring.

Electrical incidents can result in electrocution, serious burns or secondary injuries, including falls from height.

Critical controls for electrical work

Identify electrical services before work begins.

Arrange isolation or disconnection by authorised persons where required.

Maintain appropriate safe distances from overhead electrical lines.

Ensure temporary electrical equipment is suitable, maintained and protected.

Critical control verification: Confirm that required isolation and protection arrangements are in place before affected work begins. Do not rely solely on verbal assurances that electrical services are safe.

Critical risk 6: Structural collapse and falling objects

Demolition, structural alterations and temporary construction works can create risks of serious injury or death.

Examples include:

• Removing load-bearing walls.
• Installing roof trusses.
• Altering foundations.
• Dismantling structural components.
• Working beneath suspended loads.
• Removing temporary structural supports.

Critical controls for structural work

Confirm the stability of the structure before work begins.

Obtain engineering advice where required and establish appropriate temporary works.

Implement suitable exclusion zones and lifting arrangements.

Critical control verification: Ensure required structural supports have been installed and checked by a competent person before workers enter an affected area.

Critical risk 7: Silica and other harmful construction dust

Construction activities such as concrete cutting, drilling, grinding and demolition can generate hazardous airborne dust.

Respirable crystalline silica is particularly important because exposure can contribute to serious and potentially irreversible lung disease.

Other harmful exposures include wood dust, welding fumes and certain hazardous substances.

Critical controls for hazardous dust

Use suitable dust-suppression systems or on-tool extraction.

Select appropriate respiratory protective equipment where required and ensure workers are trained in its use.

Consider exposure monitoring and health monitoring where required.

Critical control verification: Check that dust-control equipment is functioning effectively and that workers are using the required protective measures.

3. How to conduct a critical risk assessment on a construction site

A critical risk assessment does not need to be unnecessarily complicated.

For small and medium-sized building companies, the most effective approach is often a practical assessment involving the supervisor, workers and relevant subcontractors.

The five-step critical risk assessment process

1. Identify the work activities. Understand the tasks, equipment, people and site conditions.
2. Identify credible serious-harm scenarios. Determine what could cause death, serious injury or serious occupational illness.
3. Establish critical controls. Identify the safeguards essential to preventing or reducing the consequences of those scenarios.
4. Verify the critical controls. Check that controls are installed, suitable and working.
5. Monitor and review. Reassess the risks as the project progresses and conditions change.

Step 1: Walk the construction site

Before work starts, inspect the site and identify activities with the potential to cause serious harm.

Do not rely entirely on a generic hazard register.

A roofing project, for example, may involve working at height, asbestos-containing materials, overhead power lines, falling objects and delivery vehicles.

Each risk requires consideration based on the actual work being undertaken.

Step 2: Talk to the people doing the work

Worker involvement is essential to effective construction health and safety management.

Ask your workers:

"What is the worst thing that could realistically happen during this task?"

"What would prevent that incident?"

"What would happen if the main safety control failed?"

These questions help identify risks that may not be obvious during a document review.

Step 3: Identify the critical controls

A critical control is a safeguard that is particularly important in preventing a serious event or reducing its consequences.

For example, properly installed edge protection may prevent a roofer from falling.

A requirement to "take care" does not provide an equivalent level of protection.

Step 4: Verify the controls

A signed Site Specific Safety Plan does not prove that the controls described in it are operating effectively.

Supervisors should physically check important controls.

This may include inspecting scaffolding, confirming electrical isolation, verifying excavation protection and reviewing asbestos survey information.

Step 5: Review the risks as work progresses

Construction sites change continually.

New subcontractors arrive, scaffolding is altered, excavations deepen and structural elements are removed.

Critical-risk assessments should be reviewed when relevant conditions, activities or control arrangements change.

4. Example critical risk assessment register for builders

A simple construction risk assessment register can help demonstrate how serious-harm risks are being identified and managed.

Construction activity	Critical risk	Critical control	Verification
Roofing	Fatal fall	Suitable edge protection	Pre-start inspection
Excavation	Trench collapse	Suitable excavation support	Supervisor inspection
Renovation	Asbestos exposure	Identification and appropriate work arrangements	Survey and removal records
Demolition	Structural collapse	Suitable structural methodology and supports	Competent-person check
Concrete cutting	Silica exposure	Suitable extraction or dust suppression	Equipment inspection
Excavator operation	Worker struck by plant	Effective pedestrian separation	Site inspection
Electrical work	Electrocution	Suitable isolation	Isolation verification

The register should identify the person responsible for each critical control and the action required if it fails.

If a critical control is missing or ineffective, the affected work must stop until suitable controls are established.

5. Critical risk assessment and Site Specific Safety Plans (SSSPs)

A Site Specific Safety Plan is a useful document for managing construction health and safety.

However, an SSSP should reflect the actual risks present on the site rather than simply repeating generic hazards.

For example, if a building project involves roof removal, the SSSP should address the relevant working-at-height, asbestos, falling-object and electrical risks.

It should also explain:

• What controls are required.
• Who is responsible for implementing them.
• How the controls will be checked.
• How workers will be informed.
• What happens if a critical control fails.

A practical SSSP helps workers understand how the job will be completed safely.

It should support actual site management rather than exist only as a document for the project file.

6. Managing critical risks between builders and subcontractors

Construction projects frequently involve several businesses working together.

Builders may engage roofers, electricians, plumbers, scaffolders, asbestos removal contractors and excavation contractors.

Each business has responsibilities relating to the risks created by its work.

However, one contractor's activities may also expose another contractor's workers to harm.

For example, roofers removing roofing materials may create falling-object risks for electricians working below.

Under the Health and Safety at Work Act 2015, PCBUs with overlapping duties must consult, cooperate and coordinate with one another so far as is reasonably practicable.

A suitable contractor health and safety management process should therefore establish how shared risks are identified, communicated and controlled.

Builders should not assume that engaging a subcontractor automatically transfers all responsibility for site safety to that business.

7. Critical control verification: How do you know your site is safe?

One of the most important parts of a construction critical risk assessment is verifying that critical controls are effective.

A hazard register may state that scaffolding is required.

A Site Specific Safety Plan may state that workers must use edge protection.

But what happens if the scaffolding has been altered or the edge protection has been removed?

A critical control verification process helps identify these failures before someone is seriously harmed.

Five questions every building supervisor should ask

1. What could kill or seriously harm someone today?

2. Which critical controls prevent that event?

3. Are those controls physically in place and effective?

4. Who is responsible for checking them?

5. What happens if a control fails?

These questions can be incorporated into daily pre-start meetings, toolbox talks and construction site safety inspections.

The objective is to identify control failures before they result in serious incidents.

8. Why construction site safety audits are important

A construction site safety audit provides an opportunity to independently examine how health and safety risks are being managed.

For a building company, this can include reviewing:

• Critical risk identification.
• Site Specific Safety Plans.
• Working-at-height arrangements.
• Contractor management.
• Plant and equipment safety.
• Worker competency.
• Emergency preparedness.
• Incident reporting and corrective actions.
• Critical control verification.

An audit should consider both the documented health and safety system and actual site conditions.

For companies working towards ISO 45001 certification or Tōtika readiness, this can also help identify gaps between existing practices and relevant management system requirements.

A construction site safety audit should result in practical findings and prioritised corrective actions, not simply another checklist.

9. How Auditsure Ltd can help builders manage critical risks

At Auditsure Ltd, we understand that builders need practical health and safety solutions that work on real construction sites.

Small and medium-sized construction companies often have limited time for complicated paperwork, but still need effective systems to manage serious-harm risks and meet their legal duties.

Our approach focuses on identifying the activities that could cause the greatest harm and helping businesses establish effective controls.

Our construction health and safety services

Critical Risk Assessments

We help identify credible serious-harm scenarios associated with construction activities and establish appropriate critical controls.

Construction Site Safety Audits

We review actual site conditions, work practices and management arrangements to identify opportunities for improvement.

Critical Control Verification

We help businesses establish processes for checking that essential safeguards are operating effectively.

Site Specific Safety Plan Development

We develop practical SSSPs that reflect the activities, hazards and control requirements of individual projects.

Contractor Health and Safety Management

We assist builders in managing shared risks and coordinating health and safety arrangements with subcontractors.

ISO 45001 Gap Assessments and Internal Audits

We assess existing health and safety management systems against relevant ISO 45001 requirements.

Tōtika Readiness Support

We help contractors review and improve their health and safety documentation and management arrangements in preparation for Tōtika assessment.

Need a critical risk assessment or construction site safety audit in Auckland?

Auditsure Ltd provides practical construction health and safety consultancy services for builders, roofers, demolition contractors and construction companies throughout Auckland and Waikato.

Whether you need a one-off construction site safety audit, a critical risk assessment or support developing your company's health and safety management system, Auditsure can help you identify the areas that matter most.

Our objective is simple:

Identify what could seriously harm your people, establish the right controls and verify that those controls are working.

Official guidance

• WorkSafe: What is a critical risk?
• WorkSafe: Understanding the changes to health and safety law

This article provides general information. Assess the work and site conditions, applicable regulations and current WorkSafe guidance for each project.