Plant Maintenance, Availability and the Workshop: The Cost Centre That Decides Your Rates

Ask a civil contractor what their excavator costs per hour and most can answer. Ask how many hours it will work this year and the answer is vaguer. Ask what its availability was last year — the proportion of the time it was capable of working when wanted — and almost nobody knows.

That third number is the one the first depends on. Fixed costs are recovered over hours worked, so a machine that achieves fewer hours than assumed carries a higher real cost per hour than the rate charged to the job. The gap does not appear anywhere. It shows up as a business that is busy and not making money.

This guide covers maintenance and availability as a commercial system rather than a workshop topic: what to measure, what regime is proportionate for an SME, how the workshop decision works, and how it feeds back into the rates in our guides to job costing and cost control and plant and equipment finance.

The number underneath every rate you quote

An internal plant rate is built from costs divided by hours. The costs are reasonably knowable — finance or depreciation, insurance, registration, maintenance, tyres or undercarriage, fuel, and a share of the workshop and fitter. The hours are an assumption.

Three consequences follow, and they compound.

• An optimistic hours assumption produces a rate that is too low, so every job is priced under cost while appearing to carry a margin.
• The error is invisible, because the shortfall lands in the plant account rather than on any job.
• It is self-reinforcing. Low rates win more work, which is taken as evidence the rates are right.

The fix is to derive the hours from history rather than from optimism. Hour meter readings at the start and end of the year, per machine, give you actual hours worked. Compare that with what the rate assumed. Most contractors doing this for the first time find the gap uncomfortable and the correction significant.

Availability, utilisation and the difference

Two different measures, frequently conflated, and each tells you about a different problem.

	Availability	Utilisation
What it measures	Whether the machine could work when wanted	Whether the machine was working
Reduced by	Breakdowns, servicing, waiting for parts, waiting for a fitter	No work, wrong machine for the job, weather, waiting on other trades, standing on site
Owned by	The workshop and the maintenance regime	The estimator, the scheduler and the business
Fix	Preventive maintenance, parts holding, capacity	Fleet composition, work pipeline, scheduling

Low availability is a maintenance problem. Low utilisation is a business problem, and it is usually the bigger one. A fleet with excellent availability and poor utilisation is a fleet that is too large, or too specialised, or bought for a job that finished — the acquisition question examined in our guide to plant and equipment finance.

Both are easy to track approximately and that is enough. A simple monthly record per machine — hours worked, days unavailable, and why — gives you both measures and takes minutes.

Why reactive maintenance costs more than it saves

The instinct in a small business is to run a machine until it stops, because servicing takes it off a job that is earning. The arithmetic does not support it, and the reasons are worth setting out because they are not all obvious.

• A breakdown happens at the worst time — mid-job, mid-pour, at the end of the month — and the consequential cost is the programme, not the repair.
• Failures cascade. Deferred servicing turns cheap components into expensive ones; a neglected filter becomes a pump, a worn undercarriage becomes a frame.
• Emergency response costs more. Callout rates, freighted parts, and a fitter dropping other work.
• Replacement hire at market rates while your machine is down, which is frequently the largest single line.
• Resale value falls. A machine with no service history sells for materially less, which matters at the point where the finance discussion happens.
• Warranty is voided by servicing outside the manufacturer’s requirements — an expensive discovery on a newer machine.
• Safety. Failures of brakes, steering, hydraulics, quick hitches and access steps are safety events, not just cost events.

The commercial framing that persuades people is availability rather than cost. A machine serviced on schedule at a planned time is unavailable for a known period you can work around. The same machine run to failure is unavailable at a time you cannot predict, for a period you cannot control.

Building a maintenance regime that fits an SME

The full manufacturer regime on a large fleet is a substantial operation. A proportionate version for a civil SME has five parts.

• An asset register — every machine, with make, model, serial, year, hour meter and the service interval. This is the same register that supports the tender plant schedule and the theft recovery position in our guides to plant and equipment schedules and plant theft and site security. Build it once.
• Scheduled servicing by hours, to the manufacturer’s intervals, with a system that flags the machine before it is due rather than after.
• Daily pre-start inspections by the operator, which is where most developing faults are first visible.
• A defect reporting route that operators actually use, with a defined response — including who decides whether a defective machine keeps working.
• Periodic condition assessment — oil sampling on major components, undercarriage measurement, structural inspection — which turns a surprise into a plan.

Schedule servicing around the work, not against it. Wet weather, shutdowns and the gap between jobs are servicing windows, and a business that plans for them converts unavoidable downtime into planned maintenance. That requires knowing what is coming due, which requires the register.

Pre-start inspections, and why they are ignored

Pre-start inspection is simultaneously a legal requirement in substance, the cheapest maintenance intervention available, and the most consistently faked record on a civil site. For vehicles over 4.5 tonnes it is also the daily check underpinning heavy vehicle maintenance accreditation, which exempts vehicles from annual registration inspection in New South Wales and Queensland — see the 2026 HVNL changes.

It is ignored for identifiable reasons, and each has a fix.

• The book asks about things the operator cannot assess, so it becomes a ticking exercise. Fix: a short checklist relevant to that machine.
• Nothing happens when a defect is reported. This is the main reason. If reporting a fault produces no response twice, reporting stops. Fix: a defined response and visible closure.
• Reporting a fault is punished by pressure to keep working. Fix: management position that a reported defect is a good outcome.
• There is no time because the operator is expected to be productive from the moment they arrive. Fix: build it into the shift.

Two items belong on every civil pre-start and are frequently absent: access steps and handrails, which is where operators are injured, as covered in our guide to working at height in civil construction; and cab air conditioning, which is a genuine heat control discussed in our guide to heat, UV and extreme weather. Cameras, alarms and beacons belong there too.

Records: the ones you need and the ones you need to keep

• Service history per machine — what was done, when, at what hours, by whom. This is the record that supports warranty, resale and any question about condition.
• Pre-start records, retained.
• Defect register — raised, actioned, closed.
• Repair history, including parts and cost, which is what tells you when a machine has become uneconomic.
• Statutory inspection and registration records where they apply.
• Hour meter readings monthly, which underpins everything in this guide.

The repair history is the one with the most decision value and the least attention. Cost per hour by machine, tracked over time, tells you which machine is quietly consuming the fleet budget and when replacement is justified — a conversation that otherwise happens on instinct. It also converts the replacement decision into evidence you can put to a financier.

Workshop, field service or outsource

Three models, and most civil SMEs end up with a mix. The decision is usually made by drift rather than by analysis.

Model	Works when	The hidden cost
Own workshop and fitter	Fleet large enough to keep a fitter occupied; work concentrated near the yard	The fitter’s cost is fixed and must be recovered; a fitter with no work is overhead
Field service vehicle	Fleet spread across sites; travel time to yard is significant	Vehicle, stock and a fitter who spends much of the day driving
Outsourced to dealer or independent	Small fleet, newer machines under warranty, or specialised equipment	Response time on a breakdown, and rates at their schedule not yours
Operator-maintained	Daily servicing, greasing and minor items	Only works with training, time allowed, and consumables available

The threshold question for a first fitter is whether there is enough work to fill the role, including scheduled servicing, breakdowns, and the fabrication and repair jobs that otherwise get outsourced or deferred. The mistake in both directions is real: hiring too early creates an overhead that must be absorbed into rates, and hiring too late means senior people spending their evenings on machines.

Where you do have a workshop, charge it out. Workshop cost recovered in the plant rate is workshop cost that appears in job costing; workshop cost left in overhead is invisible and grows.

Parts, lead times and the machine waiting on a hose

A significant share of unavailability is not repair time. It is waiting time — for a part, for a fitter, or for a decision.

• Hold the consumables — filters, oils, greases, hoses, cutting edges, teeth, pins and bushes, belts, and the common wear items for the machines you actually own. This is a small amount of working capital against a large amount of downtime.
• Know the lead times for major components on your fleet, particularly for older or less common machines. An orphan machine with a six-week part is a machine you cannot rely on.
• Regional supply is slower. A contractor working two hours from a dealer has a materially different parts strategy from one in a capital city.
• Standardise where you can. A fleet from fewer manufacturers shares parts, knowledge and service relationships, and reduces the stock you need to hold.
• Decide about aftermarket parts deliberately, including the warranty implications.
• Keep a repair-versus-hire trigger. Beyond a certain downtime, hiring a replacement is cheaper than waiting, and having decided that in advance saves a day of deliberation.

What telematics tells you, and what it does not

Most modern plant reports hours, location, fault codes, idle time and fuel burn. Most civil SMEs have this data and do not use it.

• Automatic hour capture removes the manual reading that nobody does, which makes service scheduling reliable.
• Fault codes surface developing problems before failure.
• Idle time is the most actionable number most contractors have never looked at. High idle burns fuel, accrues hours toward services, and produces nothing.
• Utilisation by machine, which answers the fleet-size question honestly.
• Location, which supports the security position in our guide to plant theft and site security.

Two cautions. Telematics does not tell you condition — it reports what the machine’s systems monitor, not the state of an undercarriage, a structure or a pin. And data nobody reads is not a system. One person, one hour a month, looking at hours, idle and fault codes is the whole implementation for an SME and it is worth more than any dashboard nobody opens.

Hired plant, wet hire and whose maintenance it is

The maintenance obligation on hired plant is set by the hire agreement, and the arrangements differ more than contractors assume — the terms examined in our guide to plant hire agreements.

• Dry hire commonly places daily servicing, greasing and fluid checks on the hirer, with major servicing on the owner. Damage and misuse are usually the hirer’s.
• Wet hire generally leaves maintenance with the owner, but you still carry duties in relation to plant used in your undertaking.
• Off-hire condition is where disputes occur. A condition report at on-hire and off-hire, with photographs, settles nearly all of them.
• Breakdown responsibility — who fixes it, in what time, and whether hire charges continue while the machine is down. This is worth negotiating rather than accepting.
• Your WHS duty does not transfer. Plant used in your business must be safe regardless of who owns it, which means you verify condition rather than assume it.

Compliance: registration, inspection and the legal side

Beyond commercial maintenance there is a compliance layer, and the requirements differ by plant type and jurisdiction.

• Registration of certain plant and plant designs is required under work health and safety regulations for defined categories. Which items require registration, and how it is maintained, is set in the regulations and is not reproduced here — confirm it with your regulator for the specific plant.
• Periodic statutory inspection for some equipment, by a competent person.
• Heavy vehicle registration and roadworthiness for on-road plant, and the maintenance obligations that sit inside heavy vehicle law — see chain of responsibility for civil contractors.
• Guarding, protective structures and safety devices maintained in working order — not removed for convenience.
• Manufacturer’s instructions, which the regulations generally require plant to be maintained in accordance with.
• Modifications, including attachments and quick hitches, which can require engineering assessment.

Quick hitches deserve specific mention. Failures involving quick hitches and dropped attachments have caused fatalities, the requirements and expectations around them have tightened, and inspection of the hitch and its locking mechanism belongs on the pre-start rather than in the annual service.

Feeding it back into the rate

The loop that closes this subject: maintenance data determines the rate, and the rate determines whether the work you win is profitable.

• Use actual hours from last year, not a target, as the denominator.
• Include the real maintenance cost per machine from the repair history, rather than a fleet average that hides the bad one.
• Recover the workshop through the rate.
• Use net fuel cost, after the rebate covered in our guide to fuel tax credits for civil contractors.
• Review annually, and specifically when a machine’s repair cost per hour climbs.
• Compare against hire rates. If your internal rate exceeds the market hire rate consistently, that is information — either the machine should go, or your assumptions are wrong.

The rate is also the tool that keeps utilisation honest. When jobs are charged an internal hire rate, a project manager who keeps a machine standing on site for three weeks sees the cost, which is exactly the behaviour change the system is for — the mechanism described in our guide to job costing and cost control.

What tenders actually ask about plant condition

Tenders rarely ask about maintenance directly. They ask questions whose real answer is maintenance.

• Plant schedule with age and condition — where a fleet age that would otherwise count against you is offset by a demonstrable maintenance regime, as our guide to plant and equipment schedules sets out.
• How will you ensure plant availability for the programme? The answer is the regime, the spares position and the replacement-hire trigger — not an assertion that your plant is reliable.
• Plant maintenance procedures as a WHS or quality returnable.
• Emissions and noise, where maintenance affects both — see embodied carbon and decarbonisation.
• Evidence. Service records and a defect register are easy to produce if they exist, and are the difference between a claim and a demonstration.

Checklist

• Do you know the actual hours each machine worked last year?
• Does the hours assumption in your internal rate match that history?
• Are availability and utilisation tracked separately?
• Is there an asset register with service intervals, and does it flag machines before they are due?
• Is servicing scheduled into wet weather, shutdowns and gaps between jobs?
• Are pre-start checklists short, machine-specific and actually completed?
• Does a reported defect produce a visible response?
• Do pre-starts include access steps, handrails, cab air conditioning, cameras and alarms?
• Is there a service history, defect register and repair history per machine?
• Do you know repair cost per hour by machine, and is it trending?
• Is the workshop charged out into plant rates rather than sitting in overhead?
• Are common consumables and wear items held in stock?
• Do you know major component lead times for your fleet, allowing for regional supply?
• Is there a decided trigger for hiring a replacement rather than waiting for a repair?
• Is telematics data actually reviewed monthly — hours, idle, fault codes?
• For hired plant, do you know whose maintenance obligation applies, and are on-hire and off-hire condition reports taken?
• Have you confirmed which plant requires registration with your regulator?
• Are quick hitches and attachments inspected at pre-start?
• Are guarding and safety devices intact rather than removed for convenience?
• Does the rate use net fuel cost and real per-machine maintenance cost?
• Do you compare your internal rate against market hire rates?

Sources and further reading

This guide is general information for Australian civil construction businesses and is not engineering, work health and safety, accounting or financial advice. It deliberately states no service intervals, availability benchmarks, utilisation targets, stock levels or plant registration thresholds: service requirements are set by the manufacturer for each machine, and plant registration and statutory inspection requirements are set in the work health and safety regulations in each jurisdiction and differ by plant type. Confirm registration and inspection obligations with your work health and safety regulator for the specific plant, and maintain plant in accordance with the manufacturer’s instructions. Modifications to plant, including attachments and quick hitches, may require engineering assessment. Maintenance obligations for hired plant are determined by the hire agreement, and your work health and safety duties in respect of plant used in your business are not transferred by hiring it. Decisions about plant replacement, financing and cost recovery should be taken with your accountant.

• Plant duties under the model work health and safety framework as enacted across Australian jurisdictions, referenced in §11 — the requirement to maintain plant in a safe condition and in accordance with manufacturer instructions, registration of prescribed plant and plant designs, periodic inspection by a competent person, and the maintenance of guarding and safety devices. The categories of plant requiring registration and the associated processes are set in the regulations and differ by jurisdiction; the regulator is the operative source and no thresholds are reproduced here.
• Heavy vehicle maintenance and roadworthiness obligations, referenced in §11, arise under heavy vehicle law and are sourced in full in our guide to chain of responsibility for civil contractors.
• The availability, utilisation and rate-derivation reasoning in §01, §02 and §12 is the guide’s own commercial analysis rather than published benchmark data. No availability or utilisation figures are given because they vary by fleet, work type and region; the recommendation is to derive them from your own history.
• Maintenance obligations on hired plant, referenced in §10, are determined by the terms of the hire agreement and are sourced in full in our guide to plant hire agreements.
• Related TenderBuilt guides carrying the primary-source detail referenced above: plant and equipment finance, plant and equipment schedules, job costing and cost control, fuel tax credits, plant theft and site security, machine control and GNSS, working at height in civil construction, heat, UV and extreme weather, tickets, VOCs and competency records and embodied carbon and decarbonisation.