Preliminaries,
the cost of running the job.

Preliminaries are the costs of delivering a job that do not become part of the finished building. The bricks, frames and fittings are permanent work; the supervisor, the site shed, the temporary power, the scaffold, the toilets, the skips, the safety signage, the job-tied insurance and the final clean are preliminaries. They are real, unavoidable costs of running the site, and on a residential build they are commonly one of the largest cost groups outside the trade packages themselves.

Within the wider discipline covered in the estimating reference, preliminaries sit in their own section of the estimate, priced separately from the measured work. That separation is deliberate and is standard practice in Australian quantity surveying. Trade rates describe what it costs to build an element; preliminaries describe what it costs to be on that site, running that job, for as long as the job takes.

Why they matter

Preliminaries matter because most of them are bought with time. A trade package is spent once, when the work is done. Supervision, amenities hire, scaffold hire and job-tied insurance are spent again every week the job remains open, whether or not any work happened that week. That makes preliminaries the part of the price most exposed to the schedule, and the part of a delayed job where money leaks without anyone raising a variation or receiving an invoice that looks unusual. A builder who understands preliminaries understands why two jobs with identical trade costs can finish with very different margins.

In the estimating workflow (see the construction estimating guide), preliminaries are priced after the measured work and the trade packages, and before margin. They are kept out of assemblies and recipes on purpose. An assembly prices a square metre of wall the same way on every job, but no two jobs run the same way, so the cost of running the job must be priced per job, against that job's site and that job's programme. The single most important input is duration, which is why preliminaries are the point where estimating and scheduling stop being separate disciplines. An estimator pricing preliminaries without a realistic programme is pricing a number without its main variable.

Preliminaries are where a delayed job quietly loses money. Every extra week on site is another week of supervision, amenities, scaffold hire and insurance with no matching revenue, and none of it announces itself. There is no variation to argue about and no supplier invoice that looks wrong, just a job that stayed open longer than the estimate paid for. Operators who have delivered enough jobs treat this as the defining property of preliminaries, and it drives two habits. They price preliminaries off the programme, not off a habit percentage, and they re-check the time-related lines every time the schedule moves, whether that movement happens during tendering or halfway through the build.

The same operators are sceptical of any preliminaries section that looks like last job's section. Preliminaries vary with job type, duration and site. A knockdown rebuild on a battleaxe block, a double-storey build needing full scaffold, and a single-storey home on an open estate lot carry genuinely different running costs, and a benchmark figure that fits all three fits none of them. Where a builder wants a benchmark, the honest answer is that there is not a reliable one, and that the discipline is itemising the section per job and then letting close-out actuals, tracked through cost control, sharpen the rates for the next estimate.

Where software fits the workflow

Traditionally the programme lives in one tool and the estimate in another, so a schedule change never reaches the preliminaries that depend on it. In VIABUILD the construction schedule and the job budget run on the same understanding of the job, so when the programme extends, the builder can see the time-related preliminaries exposure move with it instead of discovering it at close-out. The practices behind a realistic programme are covered in the residential construction scheduling guide.

Preliminaries themselves are a costing convention rather than a legislated item, but several of the costs inside them are shaped by obligations that differ by state and change over time. The points below are labelled by evidence class; confirm current requirements with the relevant body before relying on any of them.

• Industry best practice. Australian quantity surveying practice measures preliminaries as their own section of the estimate or bill, separate from the trade work, so the cost of running the job is visible and comparable between jobs. AIQS publications describe the recognised approach to measurement.
• Common practice. Many small residential builders carry preliminaries as a single percentage allowance. It is common, and it is the weakest common habit in residential pricing, because preliminaries are driven by duration and site rather than by contract value. The itemised, programme-driven section is the stronger practice this page describes.
• Common practice. Site amenities, facilities and safety provisions on a residential site are shaped by work health and safety obligations administered by each state and territory regulator, and the specifics vary by jurisdiction and job. Confirm your current obligations with your state WHS regulator rather than pricing from a previous job's list.
• Common practice. Job-tied insurances such as contract works cover are typically arranged for the expected construction period. A significantly extended programme can affect the cover and its cost, so a schedule blowout is an insurance conversation as well as a cost problem. Confirm the position with your insurer or broker for the specific policy.

Illustrative only, not a benchmark. A builder prices a twenty-week build with time-related preliminaries of $2,800 per week (a share of a supervisor, shed and amenities hire, scaffold hire, temporary services and job-tied insurance), a total allowance of $56,000 alongside the fixed items. The job hits wet weather and a slow frame stage and finishes in twenty-five weeks. No trade package went over, no variation was missed, yet the job spent roughly $14,000 of preliminaries the estimate never priced, and the contract sum did not move. Five extra weeks quietly consumed a large slice of the margin. The itemised, programme-priced section did not prevent the delay, but it made the exposure visible week by week, which is what let the builder chase the schedule while the money was still recoverable rather than discovering the loss at close-out.

Preliminaries (the costs of running a job that are not permanent work), time-related preliminaries (costs that run per week on site), fixed preliminaries (costs incurred once or per event), site establishment (setting up the site to be worked), overheads (business running costs recovered across all jobs), contract works insurance (cover tied to a specific job for its construction period), P&Gs (preliminaries and generals, the same section under its commercial-sector name). Definitions for the wider vocabulary live in the construction glossary. With the cost of running the job priced, the next question is what the business earns on top of it, which is where margin and markup picks up.

• Australian Institute of Quantity Surveyors , publisher (with Master Builders Australia) of the recognised standard method of measurement, which treats preliminaries as a distinct section of measured work.
• Your state or territory work health and safety regulator, for the current amenities, facilities and safety obligations that shape several preliminaries items on a residential site.
• Your state or territory building regulator and fair trading body, for the domestic building contract rules that govern how delay and cost adjustments operate in your jurisdiction.