A Guide to Commercial Roof Maintenance

January 27, 2025 | By: Drew Higgins
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Maintaining a commercial flat roof is critical to ensuring a long life for your building’s structural integrity and preventing costly repairs. While flat roofs are known for their durability and practicality in commercial applications, they do require consistent care. Here’s a comprehensive guide to maintaining a commercial flat roof effectively.

Understanding Your Flat Roof’s Materials

Flat roofs are typically made of materials like modified bitumen (2 ply Mod Bit), EPDM (Ethylene Propylene Diene Monomer), TPO (Thermoplastic Polyolefin), or PVC (Polyvinyl Chloride). Knowing the material specifics can help you develop a maintenance plan tailored to your roof’s needs.

Each material has specific characteristics and maintenance needs:

  • Modified Bitumen (2 ply Mod Bit): Known for flexibility and durability, modified bitumen requires regular checks for cracks or blistering, especially after temperature fluctuations.
  • EPDM (Rubber Roofing): This material is resilient but susceptible to punctures and tears. Special attention should be paid to debris removal and seam inspection.
  • TPO and PVC: These are reflective, energy-efficient options but can experience seam separation and shrinking over time.

Schedule Regular Inspections

A proactive inspection schedule is key to maintaining your flat roof’s health. Ideally, inspections should be done at least twice a year—once in the spring and once in the fall—to identify issues that may have arisen from seasonal changes. You’ll also want to perform an inspection after severe weather events like heavy rains, hailstorms, or high winds.

In my experience, some owners have stated that without regular scheduled inspections their roofs could be in danger. Buildings have sustained roof collapses due to clogged drains, and water weight building up on the roof. These collapses could have been prevented by having your roof inspected on a regular basis.

Inspection checklist:

  • Look for any debris, punctures, or visible damage.
  • Check for water ponding, as flat roofs can develop low spots over time.
  • Inspect seams and flashing for potential separation or signs of wear.
  • Note any signs of algae, mold, or moss, as these can degrade the roofing material.
  • Inspect drains and gutters for any blockages or signs of pooling water.

Keep Drains and Gutters Clear

Because flat roofs don’t have the benefit of a slope to direct water off the surface, drainage is especially critical. Water pooling is a common issue on flat roofs, and standing water can degrade roofing materials, lead to leaks, and even compromise the roof’s structural integrity.

To prevent this:

  • Regularly clear drains, scuppers, and gutters of leaves, branches, and debris, particularly after seasonal changes or storms.
  • Consider installing leaf guards or strainers on drains to reduce the accumulation of debris.
  • Ensure water flows freely by pouring a small amount of water down each drain during your inspection to confirm there are no blockages.

Address Pooling Water Promptly

Ponding water on a flat roof is a common concern due to the lack of natural slope. Over time, it can weaken the roof’s surface, create an environment for algae growth, and accelerate wear.

Tips for managing ponding water:

  • Consider adding tapered insulation to create a slight slope and direct water toward the drains.
  • For low spots causing pooling, consult with a roofing professional to have the area filled or re-leveled.
  • Install a roof pump or drainage system designed to handle flat roof runoff.

Repair Small Problems Quickly

One owner I worked with found out that a small puncture was not allowing water into the building (affecting tenants) but it was allowing water into the roof system causing major damage that was unknown. The tenants and owners were unaware of the puncture allowing water into the roof system due to not having regular roofing inspections or maintenance performed. This scenario saturated the buildings insulation and began to deteriorate the building structural decking from within.

On a flat roof, even small problems—such as punctures, tears, or small leaks—can quickly turn into costly repairs if left unattended. Taking care of these issues right away can save you time and money in the long run.

Here are a few examples:

  • If you notice a small puncture or tear in the membrane, consult a roofing expert to have it repaired professionally.
  • For blistering, where air or moisture has become trapped beneath the membrane, consult a roofing expert to have it repaired professionally.
  • If you see signs of seam separation, consult a roofing expert to have it repaired professionally.

Watch for Cracks and Blisters

As flat roofs are exposed to sunlight and fluctuating temperatures, they may develop cracks, blisters, or bubbles. Blisters can occur when moisture or air becomes trapped between the roofing layers. If left untreated, they can expand and eventually lead to leaks.

To manage these:

  • Monitor the surface regularly for any blisters, especially after temperature changes.
  • Avoid stepping on blisters, as this can worsen the issue.
  • Have a professional inspect and repair any extensive blistering.

Maintain Roof Equipment and Accessories

Commercial flat roofs often house HVAC units, vents, and other equipment. These installations can create potential weak points, as they require holes for attachment and, over time, can compromise the roof’s waterproof membrane.

Roof top equipment and accessories are the largest culprit for roof leaks during the lifespan of the roof system. At any location on the major field of the roof and the membrane is cut open to add equipment, the membrane is required to turn 90 degrees vertical to flash the penetration property. This opening or penetration to the field membrane is generally the most at-risk area on the roof for material failures. The roof membrane is similar to a rubber band, it has elasticity built into the chemical component to allow it to expand and contract during the hot and cold temperatures. As the sun’s UV rays wear and deteriorate the weathering membrane, the strength and elasticity become less and less each year.

Another major competent of leak calls are related to third party contractors accidentally puncturing the membrane. All roof top equipment needs to be serviced at sometime during its lifespan. This can relate to HVAC units, condensing units, fresh air units that are serviced monthly, quarterly, or annually. Most third-party contractors do not even know the membrane was damaged to alert the building owner or property manager. These damages or punctures are only located once the next rain event occurs, or during schedule maintenance inspections. It is strongly advised for all owners and managers to have an inspection or walk through after all major roof top projects are complete. This allows any damages or punctures to be directly tracked and associated with the work that was recently completed. This also allows any invoicing to be directed back to the contractor rather than the building owner.

Regular maintenance includes:

  • Inspecting seals and flashing around roof-mounted equipment for signs of wear.
  • Checking that equipment is securely fastened, as loose equipment can damage the membrane.
  • Monitoring vibrations, which can create wear or damage around the equipment.

Monitor for Algae and Mold Growth

Flat roofs, especially those in humid or shaded environments, are prone to algae, mold, and mildew growth. This can degrade the roofing material and, if left untreated, lead to significant structural issues.

Prevention and treatment tips:

  • Use a roof-friendly cleaner or a mild bleach solution to remove algae and mold.
  • Install zinc or copper strips along the roof perimeter to prevent growth.
  • For persistent issues, consider applying a roof coating designed to resist algae and mold.

Set Up a Professional Maintenance Plan

Working with a roofing contractor to set up a maintenance plan can be invaluable. Professionals can identify issues that may not be obvious, perform essential repairs, and apply protective treatments to maximize your roof’s longevity.

Benefits of a professional maintenance plan:

  • Contractors have the expertise to spot issues early and can help keep records for warranty and insurance purposes.
  • Professional inspections and repairs can help you comply with building codes and reduce the risk of liability in case of a roof-related accident.
  • Many contractors offer discounted rates for recurring maintenance agreements, potentially saving you money in the long run.

Proper maintenance of a commercial flat roof is essential to protecting your investment and minimizing repair costs. From regular inspections and debris removal to addressing small problems quickly and maintaining equipment, a comprehensive approach can ensure your roof serves your business for years to come. By following these steps, you can extend the life of your commercial flat roof, reduce unexpected costs, and create a safer environment for everyone in your building.

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