Hot work on residential construction sites in Australia

What it is

Hot work is any work that produces flame, sparks or sufficient heat to ignite combustible material. On a residential site that includes oxy cutting steel, MIG or stick welding structural connections, plasma cutting, grinding sparks falling near insulation or framing timber, soldering copper plumbing with an LPG torch, lead burning a roof flashing or applying a torch on torch on membrane. It is the most common cause of avoidable fires on construction sites in Australia. The duty to manage that risk sits with the PCBU in control of the work area under the model Work Health and Safety Act and Regulations.

How the WHS Regulations frame the duty

There is no single regulation that says hot work in those exact words across every jurisdiction. The duty comes from the general plant, hazardous chemicals and fire risk provisions. Chapter 7 of the model WHS Regulations covers hazardous chemicals, including LPG and acetylene used in cutting and brazing. Part 4.4 covers fire risks more broadly. WorkSafe regulators in each state publish hot work guidance that pulls the duties together. NSW, Victoria and Queensland all run hot work safety alerts after fires that started with a stray spark on an occupied or partly built dwelling.

When hot work needs a permit

A formal hot work permit is required when the work falls outside a designated safe area or when the risk assessment shows that the standard controls in the SWMS are not enough on their own. On a residential site that usually means roof work near timber framing, work in a sub floor or roof void with insulation nearby, work over a finished floor system that cannot be cleared and any hot work inside or near an occupied home during a renovation.

What a hot work permit covers

The permit lists the exact work to be done, the equipment used, the start and finish time, the worker carrying out the work, the fire watcher and the controls in place. It is signed by a competent person before work starts and signed off when the fire watch ends. SafeWork NSW issued a hot work safety alert that sets out what a permit should cover and reinforces that the permit and the fire watch are inseparable.

The role of AS 1674.1

AS 1674.1 Safety in welding and allied processes Part 1 Fire precautions sets the practical controls for hot work. It covers clearance distances from combustible material, the use of fire blankets and screens, the type and number of fire extinguishers within reach and the minimum competence of the person doing the work. It also contains an example hot work permit format that most Australian builders adapt for their own job packs.

The fire watcher

A fire watcher is a worker dedicated to watching for ignition during and after the hot work. The fire watcher does not do any other task during the watch. They have a fire extinguisher within reach, a charged hose where one is available and a way to call for help if a fire takes hold. The watcher stays on station for at least 30 minutes after the hot work stops. Sparks and slag can smoulder inside insulation, timber framing or wall cavities for far longer than the watcher expects, which is why the post work check window is fixed and not negotiable.

Two person rule for roof and void work

For hot work in a roof space or sub floor void the practice in residential construction is a two person job. One person does the work, one person watches. The watcher is positioned on the opposite side of the worker so that the watcher sees what the worker cannot. That arrangement reduces the chance of a fire starting in insulation behind the worker without anyone noticing until smoke is visible.

Gas cylinders on residential sites

Oxy acetylene and LPG cylinders count as hazardous chemicals under Chapter 7 of the model WHS Regulations. They must be stored upright, secured against falling, kept clear of ignition sources and labelled. The manifest threshold applies to larger quantities so a single set of cylinders in use on a residential job will usually sit below it, but the placarding, training and emergency planning duties still apply. Cylinders left in the back of a closed ute in summer heat have been the source of several incident notifications.

Records to keep

For each hot work job the builder should keep the SWMS, the signed hot work permit, the fire watcher details, the pre and post work fire watch sign off and any photographs taken to show clearance from combustibles. Insurance claims after a residential construction fire turn on these records.