Risk Assessment on Residential Construction Sites in Australia

Risk assessment is the bridge between a hazard sitting on a site and a control that stops it hurting someone. The model Work Health and Safety Act 2011, adopted in every state and territory except Victoria, places a primary duty on the PCBU to eliminate risks so far as is reasonably practicable, and where that is not possible, to minimise them through the hierarchy of control. On a residential build the hazards change weekly. A formal, written assessment is the only way to show a regulator the builder thought about each one before work started.

What it is

A risk assessment is the structured analysis of a hazard. It asks four questions. What can go wrong. How likely is it. How bad would it be. What will we do about it. The output is a documented set of controls tied to a specific task, location and crew. On Australian residential sites that document usually sits inside a Safe Work Method Statement (SWMS) for high risk construction work, or inside a job safety analysis for everything else.

The legal hook

Regulation 32 of the model WHS Regulations requires duty holders to manage risk in line with Part 3.1. That part sets the order of operations. Identify hazards. Eliminate where practicable. If elimination is not practicable, minimise through substitution, isolation or engineering controls. Use administrative controls and personal protective equipment only as a last resort or to top up other controls. Review controls when the work changes, when an incident happens or at regular intervals.

The How to Manage Work Health and Safety Risks Code of Practice gives the approved method. Following the Code is not the only way to comply with the duty, but it is the default benchmark a regulator or court will apply when assessing a builder's conduct.

The risk matrix

A 5 by 5 matrix is the standard tool on Australian residential sites. Likelihood runs from rare to almost certain. Consequence runs from insignificant to catastrophic. The intersection gives a risk score from low to extreme. Extreme and high scores demand immediate action and senior sign off. Medium scores need a documented control and supervisor sign off. Low scores can sit with the crew leader.

The matrix is a tool, not the answer. Two competent supervisors can score the same hazard differently. The value sits in the conversation it forces. Writing a 3 instead of a 4 next to a fall from height means nothing on its own. Writing why elimination was not practicable, and what edge protection or harness setup was chosen instead, is the part that holds up under scrutiny.

Hierarchy of control

The hierarchy is a fixed order of preference. Elimination first. Substitution next. Then engineering controls, isolation and administrative controls. PPE sits last because it only protects the person wearing it and only when worn correctly. On a residential frame, working at the bench rather than at height eliminates the fall risk. Prefabricating trusses on the ground and craning them in is substitution. Scaffold with handrails is engineering. A no go zone around an excavation is administrative. Hard hats are PPE.

Most residential builders sit too far down the hierarchy. They write PPE on a SWMS and call the risk controlled. The Code is explicit that PPE alone is not acceptable where a higher control is reasonably practicable. A regulator looking at a serious injury will work up the hierarchy and ask why each higher control was rejected.

Records and review

Records prove the assessment happened. They also protect the builder if something goes wrong later. The model WHS Regulations require SWMS for 18 categories of high risk construction work and they must be kept until the work ends, or for two years if a notifiable incident occurs. General risk assessments outside the SWMS framework should still be filed against the project. A monthly review during the build catches new hazards as the structure changes.