Properly Maintaining HVAC and Roof-Mounted Equipment

Roof damage is a major source of property loss each year when buildings are subjected to high winds, wind-driven rain, hail, ice and snow, and wildfire. A compromised roof can lead to significant damage to internal fixtures, furniture, and equipment. What’s more rooftop equipment or pieces of the roof itself can take flight during a windstorm, causing damage to the building, nearby vehicles or even neighboring property. Proper attention to all aspects of a roof can make the difference between minimal damage and catastrophic failure during high winds. To help business owners tackle roof issues, IBHS has produced a series of short papers on the installation, maintenance and repair of commercial roofs.

The focus here is on roof-mounted equipment, such as HVAC, photovoltaic systems, exhaust fans, and other mechanical units, all of which are common features on many commercial rooftops. Proper maintenance of this equipment leads to long-term savings by prolonging the life of the equipment, lowering utility bills and affording greater protection in a storm.

Energy Efficiency

Proper ventilation of roof-mounted air conditioners and air makeup units means greater energy efficiency, which leads to lower electric bills, a smaller carbon footprint and a more comfortable indoor climate for the building’s occupants. Clogged and soiled air filters can reduce air flow and affect the unit’s heating and cooling abilities. Poor ventilation also requires the unit to run for longer intervals, causing greater wear and tear on the motors and leading to a shorter operating lifetime.

Steps business owners can take:

Replace the air filter in accordance with the manufacturer’s guidelines. This is an easy and cost- effective way to help maintain a ventilation system’s efficiency.

Keeping Parts in Good Working Order

Motors, bearings and belts should be well maintained in accordance with the manufacturer’s maintenance guidelines to ensure proper operation of rooftop units.

This will help prolong the life of the unit and prevent breakdowns, which can have cascading effects on many aspects of business operations.

Steps business owners can take:

  • Keep motor and fan bearings well lubricated.
  • Ensure that rubber belts have the proper tension. Belts that slip will emit a high pitched whining sound similar to an automobile’s belt slipping.
  • Watch for signs that rubber belts have become brittle and cracked. Remember, belts * have a limited lifespan and should be inspected and replaced when directed by the manufacturer or upon signs of deterioration.

The Importance of Balance

Fan blades operate most effectively when they are well balanced. When the blades are unbalanced, the unit will vibrate and this may cause screws and other parts to loosen. An unbalanced fan reduces efficiency and compromises the unit’s secure attachment.

Steps business owners can take:

  • The greater the imbalance: the greater the vibration. This vibration may become obvious on smaller sized units but should be part of regular inspections.
  • When a roof top unit begins to vibrate and shake, contact a reliable contractor to correct problems that may cause the fans to be unbalanced.

Exterior Maintenance and Secure Attachment

Because rooftop equipment is exposed to all weather elements, it is vital to maintain the unit’s exterior and make sure it is securely attached. Corrosion and deterioration are the most common problems and can allow panels or other parts to become airborne in the event of high winds.

Steps business owners can take:

  • Inspect for rusted metal panels, screws and metal flashing on curbs, and replace as soon as possible.
  • Inspect around the unit’s connection to the curb it sits on. Check for any visible signs of potential leaks; these can be repaired using various roof sealants and caulks that are readily available.
  • If it is suspected that a water leak has occurred, the curbing itself should be inspected for rotting and replaced if needed.

Check and Recheck

While a local contractor or maintenance worker can perform most of the inspections and repairs that are necessary to keep rooftop equipment in good working order, it is important to inspect the equipment after the work is done to make sure all screws, cables, and cable straps are tightened and back in place. Failure to correctly reinstall screws and cables can compromise the unit’s overall structural integrity and leave it vulnerable to potential damage during a windstorm. For example, the panels can tear away and skip across the roof cover. This creates water leaks and, in some cases, causes the roof cover to fail.

Steps business owners can take:

  • Remind the contractor that you will not consider the job done until all parts of the unit are back in place and properly secured and all debris is removed.
  • At the conclusion of rooftop equipment repair, have maintenance staff inspect the unit to make sure that screws, cables and cable straps are tightened and reconnected.
  • Check the roof for miscellaneous debris, as well as tools that may have been left behind. Anything that is not firmly attached to the roof can become windborne debris in the event of a storm.

High Winds

During a high-wind event, unsecured equipment is subject to sliding, lifting and overturning. To prevent this, equipment should be securely attached to a curb (see photo) which is attached to the roofing structure. An equipment-to-curb connection can provide adequate uplift resistance in some instances. If the equipment connection to the curb alone is not adequate, high-strength, corrosion-resistant cables or straps should be tightly installed over the top of equipment and extend down to the curb or roofing structure. Hire a licensed contractor to help with installation. Lastly, ensure all service panels have all fasteners in place so panels do not become dislodged. For more information on attachment of roof-mounted mechanical equipment, please refer to FEMA’s “USVI-RA2 Attachment of Rooftop Equipment in High-Wind Regions.”

Is your business located in a high wind–prone area? Reinforce roof-mounted equipment with stainless steel cables and turnbuckles (shown above) to reduce risks.

High Winds – Routine Maintenance

  • Check equipment for rust on metal panels, screws, and metal flashing on curbs.
  • Inspect equipment’s connection to the curb it sits on. Look for visible signs of curb leaks; these can be repaired using readily available roof sealant and caulk. If a water leak is suspected, check curbing for rot, and replace if needed.
  • Pull on all cables and straps to verify they are tightly secured; there should be little to no slack. Check manufacturer guidelines for more specific information.
  • After all inspections and repairs are complete, re-inspect equipment to make sure all screws, cables and straps are tightened and back in place.


Hailstorms can cause significant damage to roof-mounted HVAC units. However, equipment can be protected with hail guards, which are specially designed protection systems that cover outdoor equipment components while allowing for adequate airflow. Although there are no standardized tests to compare the performance of specific systems, coil-based hail guard systems and hail guard netting seem to offer better protection in many hailstorm scenarios. These can be purchased as part of new equipment or can be installed on existing equipment.

Hail nets (shown above) can reduce HVAC system damage.

Hail – Routine Maintenance

  • Ensure hail guards are properly installed and securely fastened to prevent movement during high-wind or hail events. Contact the manufacturer immediately to address any loose or missing guards.
  • Monitor guards for any reduction in airflow to minimize compressor failure.
  • Keep guards clean and free of debris.

Winter Weather

Snow drifts can cause snow and ice to accumulate on and around roof-mounted equipment; this can result in increased loads on your roof, make leaks more likely, and affect equipment operation. Additionally, melting snow and ice can produce excess water runoff, which could cause leaks without proper drainage. One effective mitigation strategy is sloping the roofing insulation during the construction or re-roofing of a building. This guides water off the roof or to a roof drain.

Winter – Routine Maintenance

  • Clear debris from roof drains to allow proper water drainage.
  • Check for and repair cracks and sealing around roof drains.
  • Before a snow storm, clear any debris that could cause excessive ponding around and under equipment—this water can refreeze later and become very heavy.
  • If temperatures do not rise above freezing after a heavy snow storm, have a licensed contractor remove excess snow from the roof and from around equipment.


With proper design, retrofits, preventive maintenance and appropriate care of roof-mounted HVAC units, it is possible to reduce losses associated with high winds, hail and winter weather. Following the essential steps outlined above can help cut down on the need for expensive repairs, mitigate business downtime, and ultimately prevent serious damage to your business and your bottom line.