Preventive Building Maintenance for Managers--What is PM?

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What is PM?

As facilities maintenance professionals, we will never have to worry about our industry becoming obsolete. All building components will de cay, wear away, or otherwise fail eventually. As long as buildings exist: steel will rust, glass will break, motor bearings will wear, filters will get dirty, ballasts will burn out, pipes will corrode, and roofs will leak. As facilities maintenance professionals it is our job to keep these building components working for as long as possible and to make sure the inevitable equipment failures are rare occurrences. We are charged with keeping the normal effects of deterioration and wear to a minimum. The way to keep deterioration at bay is through an effective program of preventive maintenance.

The benefits of a good preventive maintenance (PM) program are huge compared to the work involved in setting up a good program. Still, few facilities have good PM programs. I have worked for facilities departments in several industries as a maintenance mechanic or maintenance supervisor. I have worked in buildings with no PM programs, in buildings with poorly designed PM programs, and in buildings with good PM programs. I can assure you that having a good PM program is worth every bit of work involved in getting the program in place.

It has also been my experience that there are few people working in facilities that know very much about setting up a good PM program. Most facilities people know PM is important, but do not really know where to start. This guide is going to show you how to create a simple yet effective PM program, tailored to your facility that will work to save maintenance costs, improve equipment performance, improve the experience of building occupants, extend equipment life, and most importantly: make your job easier.


Preventive maintenance, is the normal, everyday work we do to protect the condition of our properties and to prevent equipment failure that normally occur within a facility. PM includes all of the tasks we perform to keep a building and its equipment in good condition. Preventive maintenance includes changing heater filters, checking drive belts for wear, checking oil levels, inspecting roof flashing, greasing bearings and painting window trim. PM extends equipment life, keeps equipment running efficiently, and reduces breakdowns. Doing simple, inexpensive PM today saves time and money that would otherwise be spent doing major repairs or replacing equipment tomorrow.

Preventive Maintenance Defined

"Preventive maintenance is a scheduled program of regular inspections, adjustments, lubrication, or replacement of worn or failing parts in order to maintain an asset's function, and efficiency."

Preventive maintenance is intended to keep minor problems from escalating into major problems. Preventive maintenance allows a maintenance department to transition from a fire-fighting approach of running from one emergency breakdown to another to preventing those break downs before they occur.

Hopefully, you noticed the above definition includes the words "scheduled" and "regular." An effective PM program will ensure that everything in your building is seen on a regular schedule; whether it seems to need it or not.

A preventive maintenance schedule is basically a calendar of PM tasks to be performed. These tasks will be things such as quarterly air conditioning filter changes, monthly roof inspections, weekly checks of lawn irrigation systems, and seal coating the parking lot annually. Preventive maintenance tasks are done at regularly scheduled intervals to prevent future equipment problems.

If we wait for some piece of equipment to tell us it needs attention, that's a repair, not PM. Repairs are expensive and time consuming, preventive maintenance tasks are generally low-cost and don't take much time. Many times, expensive, time consuming repairs need to be done be cause we failed to do the cheaper and faster preventive maintenance.

I am sure that we have all had the experience of repairing some type of equipment, for example a circulating pump, and found failed bearings that were completely dry and empty of lubricating grease. And you probably thought that if someone had just greased these bearings once in-a-while, you wouldn't be making this repair now. That's what happens when preventive maintenance is neglected. Corrective maintenance be comes necessary.

The above definition of preventive maintenance says that we do PM on a building's "assets." An asset can be any building equipment or component. Assets include air conditioners, emergency generators, roofs, steam boilers, and rain gutters. Assets can be stationary, fixed, permanent parts of the building or items that are not a fixed part of a building. Items such as lawnmowers, hospital beds, or laboratory equipment are also as sets. Nearly every type of equipment can benefit from some type of preventive maintenance.


We have already briefly touched on a few reasons to do PM. Here are some others:

Reason 1: PM Extends Equipment Life

Probably the biggest reason to do preventive maintenance is that it keeps equipment running longer. The most familiar PM activity for most people is having their automobile serviced. Checking the oil level and changing the oil in our car is a PM task we all do fairly regularly. Hope fully, we do not wait until the family car breaks down to change the oil. We change the oil every 3,000 miles, or as often as the manufacturer recommends, to keep the car's engine in good condition. We do this even when the car is running well.

We know that if we don't follow the manufacturer's recommendations and service our car regularly we should expect a catastrophic engine failure within the first couple of years. In contrast, by just checking and regularly changing the oil, we can easily extend a vehicles service life to a decade or more. None of us would wait until the engine seized from lack of lubrication before we changed the oil but lots of maintenance departments operate that way.

Reason 2: PM Reduces Costs

We know that we can extend the service life of equipment through preventive maintenance. It should be obvious that extending the service life of equipment saves money. When equipment lasts longer, you do not have to buy replacement equipment as often. This reduces the long-term cost of owning the equipment. It does not take many years to realize the savings of maintaining a cooling tower and replacing it after 15 years verses ignoring it and replacing it after five years.

Preventive maintenance can also reduce costs by reducing the expense of hiring outside contractors. In all but the largest organizations, maintenance departments occasionally rely on outside contractors with specialized skills. If PM is not being performed consistently by your in house staff, problems that often could have been prevented in-house can become expensive problems requiring the more costly repair services of these outside contractors.

One of the most familiar examples of this happens very often with air conditioning. If an air conditioner's air filter is not changed regularly, the filter will eventually become clogged with dust, blocking air flow through the evaporator coil. When this happens, the evaporator coil can freeze due to the reduced air flow. An air conditioner with a frozen coil will no longer provide cooling and condensate will drip from the ice creating a puddle on the floor. If a small maintenance department does not have staff certified by the EPA to work on air conditioners, an outside contractor will need to be called to make repairs.

With travel time charges, and hourly minimum charges, it can easily cost $200 or more to have a technician change a filter that you could have changed in-house for less than $10.00 including labor and materials. I've seen "frozen coil-changed filter" written on service tickets more times than I would like to admit.

Equipment downtime, or the time that equipment is not working, can also be a source of increased costs. Proper preventive maintenance of equipment will reduce downtime. I once had the embarrassment of shut ting down 40 occupied hotel rooms because an air conditioning unit failed.

The compressor had a slow oil leak that we had not seen which eventually caused the compressor to fail. The hotel I worked for catered to a clientele of corporate executives who were usually in our area on extended business.

Because we overlooked this oil leak, the hotel lost the night's room revenue on 40 rooms; had to hire a shuttle bus to move everyone to a competing hotel for the night; had to pay for 40 guest rooms at the competing hotel; had to hire the shuttle bus again the following morning to get every one back to our hotel so everyone could get ready for work; and offered everyone some very nice and expensive complimentary meals, drinks, and outings for their trouble. Half of our inconvenienced guests decided to stay at the competing hotel and we were left with empty rooms for several nights. Since hotels make their money on "heads in beds," these empty beds were revenue losers.

We had been changing AC filters regularly but were not doing routine inspections to look inside the cabinets to check for any obvious problems. If we had been inspecting these properly, we would have noticed the puddle of oil weeks before the compressor failed. We saved the 10 minutes of work that it would have taken to do the inspection. We lost thousands of dollars of room revenue as a result. You can bet I do visual inspections on AC units as part of my PM program now.

Reason 3: PM Saves Energy

Energy costs can also be reduced by simple PM tasks. With the re cent increase in the cost of natural gas, electricity, and fuel oil, the energy savings created by preventive maintenance are more important than ever.

Slipping drive belts, dirty electric motors, and clogged air filters all cause increased energy usage and are easily correctable through proper PM.

In the previous example of a dirty air conditioning filter, not only would such an ac unit freeze up but the efficiency of the unit would de crease dramatically during the last few months the unit struggled to per form with such dramatically reduced air flow. A modern high-efficiency air conditioner with a dirty filter will no longer perform at its designed high-efficiency. Replacing a $5.00 filter and cleaning a clogged evaporator coil can reduce the amount of electricity used by 50% or more. Regular filter changes can be expected to reduce overall air conditioning operating costs by 8 to 10%. For large facilities, this can mean thousands of dollars in energy savings each season.

Other examples of PM tasks that can save energy are: inspecting roofs for wet insulation which allow thermal losses, maintaining window caulk, inspecting weather-stripping on doors, and making sure that auto mated building comfort systems are operating properly.

Reason 4: PM Improves the Experience of Your Occupants

Whether you maintain a retail space, a healthcare facility, a hotel, a schools, an office building, or some other type of facility; you have control of small details that can either make your building occupant's experience positive or negative. Air conditioning or heating systems that fail regularly, parking lots littered with broken glass, roofs that leak, fire alarm systems with frequent false alarms, and rest room partition doors that do not latch are just a few examples of the small but very frustrating experiences that can be solved with a simple PM program of scheduled inspections and repairs.

If your tenants are regularly complaining about maintenance problems that need attention, this is a sign that you need a PM program. With a good preventive maintenance program in place and working for you, the maintenance department can become almost invisible since you will be working behind the scenes to keep things running without breakdowns instead of working to fix tenant complaints after breakdowns occur. Once a PM program is in place, you will find and solve these problems before your building occupants do.

Reason 5: PM Makes Your Job Easier

We know that PM extends equipment life, saves your company money, saves energy, and improves the experience of your building's occupants. As the maintenance manager you are probably wondering "What's in this for me?"

Here is what you and your department can get out of a good PM program:

• Fewer midnight emergency phone calls

• Fewer weekends and late nights at work

• Fewer angry phone calls from dissatisfied building occupants

• Less stress

• More satisfaction and pride in the improved condition of your facility.

I have set up PM programs at several properties during my career. I can tell you from personal experience that starting a PM system will be a lot of work in the beginning but the extra work is definitely worth it in the long run. In the beginning it will be hard to find the time to do all of the preventive maintenance tasks on your new schedule. Lots of maintenance departments realize the importance of PM but don't do any, because they are just too busy running from emergency to emergency to find the time. Keep your eye on the prize because if you can stick to your PM schedule for one complete cycle, typically 3 months, you will see a sudden and dramatic decrease in these emergencies. It works and it is worth every bit of extra work required in the beginning.

Even with all the benefits a PM program provides to the bottom line, building occupants, and the maintenance department, it is estimated that only 15% of buildings have comprehensive preventive maintenance pro grams.


PdM stands for predictive maintenance. Predictive maintenance is similar to PM (preventive maintenance) in many respects. You will some times hear the terms PM and PdM interchanged. Like preventive maintenance, predictive maintenance is used to keep equipment in good repair and fix problems before the equipment fails. The difference between the two is that PM is time-based while PdM is condition-based. That means that PM tasks are scheduled according to a calendar while PdM tasks are scheduled when indicated by some sort of measurable wear factor.

Changing air filters every 3 months would be considered PM since the schedule is time-based-every 3 months. Changing air filters only when the filters are getting dirty would be PdM. Many commercial air conditioners offer this feature. Many AC units have pressure sensors in the air filters compartment and will flash the word "filter" on the thermostat display when the air filters are beginning to get dirty and the air flow is starting to become obstructed. Because the filter change interval depends on a measured reduction in air flow, changing these filters would be considered PdM instead of PM.

PdM requires constant monitoring of equipment conditions. PdM offers some cost savings because maintenance tasks are only performed when needed. However, the costs of continuously monitoring the condition of equipment often outweigh the savings.

PdM is more common in industry and manufacturing maintenance than it is in facilities maintenance. An entire field of reliability engineering has developed in the manufacturing sector which uses techniques such as vibration analysis, thermal imaging, oil analysis, and ultrasonic detection to inspect all sorts of equipment to predict component failures before they occur. All of these expensive techniques make sense in a manufacturing environment where a single machine can cost millions of dollars and where machine down time can cost thousands of dollars in lost production every hour.

Facilities maintenance does not involve the same types of costly one- of-a-kind machinery found in industry. Facilities equipment is also less complex and less prone to failure than the custom-built machinery found in manufacturing plants. This is why PdM is more often used in industry and manufacturing than it is in facilities. However, there are some predictive maintenance technologies that have been borrowed from industry that fit well with preventive maintenance of buildings.

Thermal Imaging

Thermal imaging is becoming more commonplace in facilities maintenance. A thermal imaging camera is able to record temperature in the same way a regular camera records color. Thermal cameras can identify problems by letting the camera operator actually see hot and cold.

The primary use for thermal imaging in facilities maintenance is to detect electrical problems before they cause failures. Corroded or loose electrical connections cause a point of high electrical resistance. High resistance points will overheat as electrical current passes through them.

Overheating can eventually lead to melted wire insulation, damaged or tripping circuit breakers, blown fuses, and other heat related damage to electrical equipment. A thermal imaging camera can see these hot spots long before damage is done.

Thermal imaging is also used to detect defects in the building envelope. The building envelope encompasses roofs, walls, windows, or doors.

Thermal imaging can display the heat or cooling energy losses and tell you exactly where you have cracks or missing insulation. Warm or cool spots on your building indicate that your heating or cooling energy is escaping at these locations.

Contractors performing roofing inspections often use thermal imaging cameras to detect water under the roof's surface. During the heating of day, or cooling of night, water saturated insulation trapped under the roof surface will maintain its temperature longer than dry insulation. By looking at thermal images of the roof, it is possible to detect hidden areas of water damage without damaging the roof by taking core samples. In the same way, thermal imaging can be used to find water in concrete block, brick, ceilings, or carpets. Early detection of water can be valuable in keeping the building structure from deteriorating.

Group Re-lamping

With fluorescent or high intensity discharge (HID) lighting, it can make sense to re-lamp an entire facility at one time rather than changing bulbs as they burn out. Fluorescent and HID bulbs tend to have similar expected lifetimes so it can be assumed that the majority of these bulbs will fail at nearly the same age. If we know at what age the lamps can be expected to fail, we can change a group of lights together just before this mass failure occurs. Fortunately, lamp manufacturers are able to pro vide expected lifetimes for their lamps under a variety of operating conditions.

Another reason to re-lamp a facility is a trait of all HID lamps known as lumen maintenance. As HID lamps age, their light intensity declines.

Some HID lamps can loose 40% of their light output by the time they reach the end of their service life. In many cases, a facility may decide to re-lamp to maintain the original light levels. FIG. 1 shows the expected life and lumen maintenance of several common types of lamps.

Group re-lamping is considered PdM since a measured number of bulb failures (by the manufacturer in field testing) or a measured decrease in light intensity is used to determine when to schedule the activity.

Facilities that group re-lamp tend to do so roughly every five years and are able to eliminate all of the man hours spent setting up ladders or other equipment to change bulbs every day as they burn out. Areas such as conference centers, warehouses, auditoriums, gymnasiums, and high way signs often have difficult access to lighting due to their height. Setting up cranes or aerial lifts once every five years instead of every time a bulb blows out makes group re-lamping an attractive option.

As you can see, some of our planned maintenance activities are actually PdM rather than PM. However, the two terms are very closely related and the term preventive maintenance is more common in the field of facilities maintenance. We will use the term PM whether an activity is condition-based or time-based to describe all planned maintenance activities.

Infant Mortality and the Bathtub Chart

If you are considering group re-lamping for your facility, you should be familiar with a phenomenon that reliability engineers call "infant mortality." The concept is simple: Due to manufacturing defects or installation errors, new equipment is more likely to fail than equipment that has already survived its "burn in" period. This premise applies to all new equipment, including lamps. Engineers call a graph of failure rates over time, as shown in FIG. 2, a "bathtub chart" because of the shape of the curve.

FIG. 1

FIG. 2

If all the lamps in a facility are replaced at the same time, there will be a brief period of a few weeks when there will be a high number of lamp failures (left side of chart)

This is because any factory defects will show up when the lamps are first put into use. After this initial "burn in" period, when all the defective lamps are weeded out, the failure rate will drop considerably and will remain relatively constant for several years (middle of chart) with a few failures expected each year.

Near the end of the lamps' expected life, the failure rate will increase again as lamps fail due to age (right side of chart)


There are many types of maintenance tasks performed by the facilities maintenance department. In fact, many organizations are missing out on the benefits of PM and do very little PM at all. FIG. 3 shows a flow chart of the different types of maintenance done by maintenance departments. These types are discussed in detail below.

Corrective Maintenance

Corrective maintenance is also known as "reactive maintenance" or just "repairs." Corrective maintenance is fixing something that is already broken. This type of maintenance is probably the most common type of maintenance done in most facilities. In organizations that do not do PM or do very little PM, the amount of corrective maintenance can become overwhelming. The purpose of a PM program is to reduce the amount of corrective maintenance that needs to be done. Even with an effective PM program is in place, corrective maintenance can never be completely eliminated.

FIG. 3

As its name implies, corrective maintenance is any maintenance that corrects a problem; as opposed to PM that attempts to prevent problems before corrective maintenance is necessary. A few familiar corrective maintenance tasks would include patching leaking roofs, replacing motors with seized bearings, and replacing burned out fluorescent bulbs.

Most corrective maintenance comes to the maintenance department from complaints by building users. These complaints may be phone calls requesting that repairs be made or can be in the form of paper or computerized work orders. Corrective maintenance needs to be performed timely to keep building users content but cannot get in the way of performing PM tasks. One of the hardest parts of managing a maintenance department is to stay on-task with scheduled maintenance while other emergencies are coming in. I am not suggesting that you ignore the corrective maintenance that needs to be done, only that you keep PM as your priority. In the long term, PM will have a much larger impact on building condition (and therefore building occupants) than corrective maintenance.

Deferred Maintenance

Deferred maintenance is another way of saying "no maintenance." Deferred implies that we will do some maintenance in the future but not today. Maintenance is often "deferred" when there are budget crisis.

If it is expected that maintenance funding will be available at some date in the future, the costs of needed repairs should be recorded as break downs occur. Knowing an accurate cost of "catching up" will be a valuable budgeting tool in the future.

If an organization is anticipating moving to a new location or closing a local branch, maintenance may be deferred so that money is not spent on maintaining assets that will soon not be needed. In this case, the term "deferred" is still used although there are no real intentions of doing the needed work later.

Run to Failure

A "run to failure" policy may make sense for very inexpensive equipment or building components that can be replaced more cheaply than they can be repaired. Small office tools such as pencil sharpeners or coffee makers would most likely not be part of your PM program. If you were to disassemble and lubricate and vacuum out the tiny motor on a pencil sharpener, you could likely extend its service life. But you can replace the entire unit for less than the cost of labor to do the PM. Good judgment would be to choose "run to failure" as the best course of action. A desktop pencil sharpener might be a silly example, but there are lots of small items you will not choose to include in your PM program for this same reason.

If you can repair or replace a piece of equipment as easily and cheaply as you can PM it, then a "run-to-failure" strategy will save time and money in the long run.

Emergency Maintenance

Emergency maintenance is the more urgent sibling of corrective maintenance. While corrective maintenance needs to be done timely, emergency maintenance needs to be done immediately. Emergency maintenance can include gas leaks, broken water pipes, roof leaks, broken windows, backed up sewer lines, no heat calls in winter, no cooling calls in summer, snow and ice removal, or any maintenance issue that puts your facility or people at risk of further harm.

Emergency maintenance is the most disruptive type of maintenance to a well planned PM schedule. Emergency maintenance is the reason I recommend scheduling PM tasks for particular weeks and not for particular days. We have all had days when "all hell breaks loose" at work. If we had PM tasks assigned for that particular day, those tasks may go undone.

If we have PM tasks scheduled for any time during that week, there is enough flexibility for your PM program to recover.

Safety, health, and environmental compliance items usually make up a large percentage of emergency maintenance. These items, sometimes referred to as the acronym SHE, can often be prevented through proper PM but need to be attended to immediately when there is a problem that could potentially harm building occupants, the public, or the environment.

Emergency maintenance can have the largest cost per job of any work you do. These maintenance projects often require keeping maintenance staff on-site after hours or calling staff back in the middle of the night. It may also require the services of outside contractors who can charge staggeringly high fees for emergency response. In addition, there's usually not time to get competing price quotes for emergency work which can result in higher costs.

Call-back Maintenance

The category of maintenance that I dislike most is when I have to send one of my maintenance people back to do a repair again. Fortunately this does not happen often.

After making repairs, front-line maintenance personnel should be expected to do two things. First, verify the original problem is gone. This means to not only replace the obviously defective part but to also operate the equipment after the repair is made to verify that it is operating properly. The second expectation is that they spend a few minutes inspecting the rest of the equipment and looking for other problems that might arise.

Maintenance personnel need to always be on the lookout for anything that might become a problem later. An attitude of continual improvement is invaluable and is what PM is all about.


You must have an attitude of continual improvement for PM to be successful.

PM should not only happen at the scheduled time. Every time maintenance personnel remove the cover on a piece of machinery to make a repair, they should consider themselves, not only repair technicians, but also PM mechanics looking for and correcting other problems.

Call backs make a maintenance department look incompetent. A mechanic with a large number of call backs may be incompetent.

The flowchart in FIG. 3 shows the relationship between the different types of maintenance.


Most of us did not have the opportunity to help with planning our buildings. Most of us maintain buildings that were built long before our tenure. The best maintenance planning begins with a building's design.

Many times, building designers neglect considering future maintenance needs in favor of creating aesthetically pleasing spaces or keeping construction costs down. We've all worked on air handlers above drop ceilings, been in plumbing chases that would make rats claustrophobic or had to use a hand mirror to see inside some piece of equipment that needed repairing. If you are fortunate enough to ever have the opportunity to help in the design process of a new building, emphasize the importance of considering future maintenance needs.

Like most of us, you are probably working in buildings that were built without a lot of consideration for those of us who would someday have to take care of the facility. Even in this situation, there are things you can do to make your building easy to care for as possible.

By standardizing items such as plumbing fixtures, emergency lights, and door hardware you can reduce your repair parts inventory and re duce the learning curve on new equipment. When ordering parts or re placement equipment, try to order exactly what you already have in place and try to keep everything the same. Having to stock parts for 30 different brands and models of faucets will take up a storage cabinet. If all the faucets in your facility are the same, a small drawer of parts is all you need.

Taking the time to create easier access to equipment that requires frequent service will save you time in the long run. This may mean installing access doors in walls or ceilings, installing ladders or roof hatches, or even relocating equipment to a more suitable location. The hours spent making these modifications can save many more hours in the accumulated minutes required to get to things that are hard to reach.

Sometimes we can find ways to make equipment easier to service. Difficult to reach grease fittings can be relocated using grease port extension kits. Access doors can be cut into equipment to allow access to areas that need frequent service. Sight glasses or Plexiglas or Lexan windows can be installed to allow inspection of the inside of all sorts of equipment without requiring the removal of any machinery covers. Remember that the easier it is to perform PM, the more likely it is that PM will be done.

Whenever building alterations are being planned or major equipment is being purchased, the maintenance department should be included in the process to ensure that future maintenance needs are being properly considered.


• Preventive maintenance includes all of the work we do to keep our building components and equipment operating in their original condition.

• Preventive maintenance is a scheduled program of regular inspections, adjustments, lubrication, or replacement of worn or failing parts in order to maintain an asset's function, and efficiency.

• PM tasks include greasing and oiling bearings, changing filters, changing oil, group re-lamping light fixtures, inspecting drive belts, and many other simple tasks.

• Predictive maintenance (PdM) depends on the condition of an asset to decide if it is the right time to perform maintenance. While preventive maintenance (PM) schedules are time based.

• PM does not require condition monitoring which can be costly.

• PdM does not schedule unnecessary maintenance which can also be costly.

• Preventive maintenance is an important part of facilities maintenance because:

- It extends equipment service life

- It reduces equipment break downs and emergencies

- It saves money by extending service life and maintaining equipment efficiency

- It improves the experience of building occupants

- It makes the work of the maintenance department more manageable

• All maintenance activities that are not PM will fall into the categories of

- Predictive Maintenance

- Corrective Maintenance

- Deferred Maintenance

- Emergency Maintenance

- Call Backs

• When an effective PM program is implemented, the focus of the maintenance department will shift from dealing with breakdowns and emergencies to planning and following a schedule of preventive maintenance tasks.


You must have an attitude of continual improvement for PM to be successful.

• Building design and prior planning can have a large impact on the maintainability of a building. Considerations such as equipment ac cess and standardizing of repair parts can make maintaining a building much easier. The easier it is to maintain a building, the better the chances are it will be done properly.

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