Preventive Maintenance: A Practical Guide to PPM

Preventive maintenance is work you do to keep an asset healthy on a planned basis — an inspection, a service, a part swap — scheduled ahead of time rather than triggered by a failure. In the UK it's often called PPM (planned preventive maintenance). It sits between two extremes: purely reactive "run to failure", and fully predictive maintenance driven by sensor data.

Why preventive maintenance pays

Reactive maintenance feels cheaper because you only pay when something breaks. In reality it's the most expensive mode of all: emergency call-outs, expedited parts, unplanned downtime, collateral damage, and safety risk. Industry studies consistently put reactive repairs at several times the cost of the same work planned. Shifting even part of your workload from reactive to planned typically delivers:

• Less unplanned downtime — the failures that stop production or close a site.
• Longer asset life — assets maintained on schedule last measurably longer.
• Predictable cost and labour — planned work can be batched, resourced and budgeted.
• Compliance you can prove — statutory checks happen on time, with a record.

The four types of maintenance

It helps to know where PM sits on the spectrum:

Type	Triggered by	Best for
Reactive	Failure	Low-value, non-critical assets
Preventive (time-based)	A calendar interval	Most assets — the default
Usage-based	Hours / miles / cycles	Vehicles, machinery
Predictive / condition-based	Sensor readings	Critical, instrumented assets

You don't need to pick one. A mature programme uses reactive for cheap, non-critical items and reserves planned and predictive effort for the assets that hurt when they fail.

How to build a PPM programme — step by step

1. Build your asset register

You can't schedule maintenance on assets you haven't listed. Start with a register — every asset, its location, make and model. This is the foundation of any CMMS, and the single most valuable thing most teams are missing.

2. Prioritise by criticality

Rank assets by what happens when they fail — to safety, production, cost and compliance. Don't try to schedule everything at once; concentrate planned effort where downtime is most painful.

3. Define the tasks and intervals

For each critical asset, decide what needs doing and how often. Start with the manufacturer's recommendations and recognised standards (for building services, SFG20 is the common reference), then adjust based on your own failure history.

4. Schedule and assign

Turn those tasks into recurring, auto-generated work with an owner and a due date. The goal is that the work appears in someone's queue when it's due — nobody should have to remember it.

5. Capture the work properly

Use photo-backed checklists so a completed job is evidenced, timestamped and signed off — not just ticked on paper. This is what turns maintenance into an auditable record.

6. Measure and refine

Review the data monthly and adjust intervals. Over-maintaining wastes labour; under-maintaining risks failure. The history tells you where the balance is.

The metrics that matter

A PPM programme is only as good as what you measure. The core maintenance KPIs:

• Planned vs reactive ratio — the headline number. World-class operations run 80%+ planned.
• PM compliance — the share of scheduled maintenance completed on time.
• MTBF (mean time between failures) — is reliability improving?
• MTTR (mean time to repair) — how fast do you recover when something does fail?
• Maintenance backlog — is overdue work growing or shrinking?

Common mistakes to avoid

• Scheduling everything. A calendar full of low-value tasks buries the important ones and burns out the team.
• Paper sign-offs. If a job can't be evidenced, it can't be trusted or audited.
• No feedback loop. Intervals set once and never revisited drift out of line with reality.
• Ignoring the field. If technicians can't log work on a phone, offline, the programme lives only in the office.