Reactive, Preventive, and Predictive Maintenance: What Is the Difference?

Every building needs maintenance, but the timing of that work can follow very different rules. Some items are repaired after they fail. Others receive service on a schedule. Equipment can also be monitored for changes that suggest a developing problem.

These approaches are known as reactive, preventive, and predictive maintenance. Understanding the difference helps explain why a maintenance plan involves more than a calendar of recurring visits.

Reactive maintenance: work after a failure

Reactive maintenance responds when something stops working. A failed component is repaired or replaced, rather than serviced in advance to avoid that failure.

The Department of Energy's maintenance-program guide explains that this approach can involve unplanned downtime, overtime, and damage to related equipment.

However, not every inexpensive item needs an elaborate maintenance program. Consider a replaceable, noncritical accessory with a spare readily available. Waiting for it to fail may be a deliberate operating decision. That decision looks very different when the item serves an essential building function.

Preventive maintenance: work on an established schedule

Preventive maintenance uses time or operating intervals to organize service before failure. Tasks may include scheduled inspections, lubrication, or replacement of wear items, as appropriate to the equipment and its instructions.

Its advantage is structure: the work has a planned place in the schedule. Its limitation is that a calendar does not describe the exact condition of every component. A part may still be usable at its replacement interval, while another may develop a problem sooner.

Preventive work can reduce failures; it does not guarantee that breakdowns disappear.

Predictive maintenance: work informed by condition

Predictive maintenance uses measurements and analysis to detect deterioration and help determine when service is needed. The DOE guide describes tools such as vibration analysis, infrared inspection, and oil analysis.

The useful distinction is the decision trigger. Preventive service follows an interval. Predictive service responds to evidence about the equipment's condition.

Installing a sensor alone does not complete the process. Someone must interpret the information and decide what action it warrants. A temperature reading, for example, becomes more useful when the team understands the equipment's normal operating pattern.

Why buildings may use a mix

Pacific Northwest National Laboratory discusses the benefits and limitations of these approaches. There is no reason every asset in a building must follow the same strategy.

A practical evaluation asks:

• What happens if this item fails?
• Does it affect safety or essential operations?
• Can its condition be meaningfully monitored?
• How long would repair or replacement take?
• What maintenance does the manufacturer specify?

Imagine two identical components: one supports a rarely used secondary space, while the other serves the building's main operating area. Their physical design may be the same, but the consequences of failure differ. That difference belongs in the maintenance decision.

Records connect the strategy to the work

A maintenance record should explain what was inspected, what was found, what action was taken, and what remains unresolved. Repeated complaints without a documented finding make it difficult to distinguish a recurring defect from unrelated incidents.

For example, an entry that says “door repaired” provides less useful history than one identifying the door, the observed problem, and the adjustment performed.

Maintenance planning becomes more useful when the timing of work follows both the equipment's needs and the consequences of losing it.