By Greg Allan, tradesman and creator of Data First Coaching
Why does a safety incident on site cost a builder more than the invoice shows?
A stop-work order, an injury, or a certifier flag at frame stage or lock-up almost never shows up as one clean line in the job costing. It shows up as a lost day of labour, an idle subcontractor, a delayed progress claim, and sometimes a variation the builder ends up wearing because none of it was priced into the fixed price or cost plus contract in the first place.
Picture a builder mid frame stage on a new home, stood down for an afternoon after a site visit flags an unguarded edge. The crew goes home, the site supervisor loses a morning to paperwork instead of preparing for handover, and the certifier's next inspection slips by a week. None of that labour or delay was in the original estimate. On a renovation or extension already running a tight margin, a day like that can turn a healthy quoted job into one that barely covers its costs, and because the cost lands after the contract is signed, it is often absorbed into overhead instead of being traced back to the job that caused it.
What are a builder's core duties under the Health and Safety at Work Act?
Under New Zealand's Health and Safety at Work Act 2015, a builder running a building business is what WorkSafe calls a PCBU, a person conducting a business or undertaking, and that status carries a duty to ensure, so far as is reasonably practicable, the health and safety of workers and of anyone else the work could put at risk. This applies whatever contract type sits over the job.
That duty, set out in WorkSafe's guidance on PCBUs working together, covers your own crew, any subcontractor and their workers while on your site, and anyone else the work could affect, including a homeowner still living in part of the house during a renovation. It applies whatever the contract type or site stage, slab, frame or lock-up. WorkSafe's guidance on general risk and workplace management adds duties around training, supervision and protective equipment for everyone on site, not just direct employees.
There is one wrinkle specific to new home builds: WorkSafe's policy for people building or working on their own home explains that a homeowner having a house built is themselves a PCBU for the build, but notes that in most cases the owner meets that duty by engaging a competent, qualified builder, whose business then carries the practical safety role on site, see information for people building a house or working on their own home. That does not remove the builder's own duty, it sits alongside the homeowner's.
What duties apply once subcontractors and other trades are on site?
Where a builder shares a site with subcontractors, each business carries its own duties, and WorkSafe requires PCBUs whose duties overlap to consult, cooperate and coordinate so the work does not fall into the gap between trades, which matters most at busy stages like slab pour, frame stage or lock-up when several subcontractors are scheduled on site at once.
This overlapping duty sits in the Act itself, covered in WorkSafe's guidance on overlapping duties under the Health and Safety at Work Act. WorkSafe has also signed off a new approved code of practice for residential construction, giving builders and subcontractors clearer examples of who holds which role on a house building site, due to take effect in twenty twenty-seven, see new ACOP to clarify health and safety responsibilities on residential construction sites. WorkSafe is clear the new code does not create extra duties, it clarifies the existing ones with examples from residential building work, so the obligations a builder carries now are the ones that will still apply once it lands.
What has to happen if there is an injury or notifiable event on site?
If a notifiable event happens on a building site, the builder, as the PCBU managing or controlling that workplace, must notify WorkSafe as soon as possible after becoming aware of it, under section 56 of the Health and Safety at Work Act 2015, preserve the site until an inspector allows work to resume, and keep records of the event for at least five years.
That preservation duty matters for scheduling as much as compliance: a site that cannot be touched until an inspector clears it means lock-up or handover can slip, a certifier's next visit may need to be rebooked, and a progress claim tied to that stage can sit unpaid longer than planned. The detail of what counts as notifiable, and exactly how to notify, is set out in WorkSafe's own quick guide to notifiable events and in section 56 of the Health and Safety at Work Act 2015. This is general information, not legal, tax or employment advice. Check your own situation with the body named here or a qualified adviser.
How do you keep the cost of working safely inside the quote instead of the overhead?
You protect your gross profit margin by pricing the real cost of working safely into every line of the estimate, the same way you price labour, materials and time, rather than treating safety as background overhead that gets absorbed after the job is finished.
That means scanning a site proactively, before frame stage or lock-up, for what could go wrong, rather than waiting for a certifier or an inspector to find it first. A hazard spotted and priced in during estimating is a cost you control. The same hazard found after the crew is on site, or after a subcontractor turns up without the right paperwork, becomes a cost that eats straight into that job's margin.
This is also where data first thinking matters more than memory. Knowing which stages, which subcontractors or which sites have produced delay, rework or a near miss before, read from your own job and site records week by week, tells you where to put attention now, rather than relying on a general feeling that it's usually fine. A decision about supervision, training or protective equipment made from memory is usually a decision made on an old picture of the business.
This is also where AI agents can help. An AI agent is software that does a job the way you would, following your own wording, your own site rules and your own prices. AI agents can hold training records, notifiable event logs and subcontractor compliance paperwork the way you want them kept, and flag a missing certificate before a subcontractor turns up on site rather than after. That frees the site supervisor and the office to spend their time on the crew and the next job, not chasing forms.
Where can you check the current rules?
The duties above come from WorkSafe's own guidance and from the Health and Safety at Work Act 2015 itself, and because the detail changes as rules update, the safest place to check the current position for a building business is directly on WorkSafe's site and in the legislation, not from a general summary written for every trade at once.
- Introduction to the Health and Safety at Work Act 2015: WorkSafe's overview of the Act, what a PCBU is, and who is covered.
- PCBUs working together: advice when contracting: guidance on duties when a builder and subcontractors share a site.
- Information for people building a house or working on their own home: WorkSafe's policy on homeowner and builder duties during a build.
- General risk and workplace management: duties around training, supervision and protective equipment.
- New ACOP to clarify health and safety responsibilities on residential construction sites: WorkSafe's announcement of the new residential construction code.
- Appendix C: Health and Safety at Work Act duties: overlapping duties and worker engagement.
- Quick guide: what events need to be notified: what counts as notifiable and what to do about it.
- Health and Safety at Work Act 2015, section 56: the legislation itself on the duty to notify.
How does Data First Coaching approach this?
Data First Coaching does not start by asking a builder to describe their safety record, it starts with the job and site data the business already has: which stages have caused delay before, which subcontractors have been stood down, where a certifier visit has slipped, and what that actually did to the margin on those jobs. Reading that through the Trade Business Intelligence shows whether a safety cost is a one-off, or a pattern sitting upstream of how jobs are quoted and scheduled. As Greg puts it, “you know what you're looking at and the customer doesn't,” which is exactly why the duty to look properly sits with the builder. The how, worked through with members inside the Academy, is for owners who are open minded, innovative and willing to share, because the Trade Business Intelligence is powered by every member.
Looking for a business coach who starts from your numbers? Builder Business Coach or every answer for builders.
