Proper drainage is one of the most critical elements of any healthy commercial roof system, yet it is often overlooked. When roof drains become clogged with debris, the consequences can be severe. Standing water that ponds for prolonged periods will inevitably lead to damage of your roofing system. Problems like membrane blistering, insulation saturation, mold growth, and voiding of warranties are just some of the issues caused by poor drainage. In this blog, we will look at the importance of keeping roof drains flowing freely on flat roof buildings.

Maintaining clear roof drains and gutters through routine maintenance is essential to maximize the longevity and integrity of your commercial roof system. By understanding why proper drainage matters, property owners can take proactive steps to keep their rooftop drains open and working and gutter system flowing freely. Doing so will help avoid thousands in commercial roof repairs or a premature roof replacement.

Your roof was designed to move water continuously over and off your roof system. Roofing materials were not made to be consistently exposed to ponding water. As water sits on your roof system, it will find weak and failing areas to penetrate your roof system. This is when a small and inexpensive fix becomes a complex and expensive repair. Roofing expert Chris Alexander shared, "The most expensive repair on a flat roof system is having to replace sections of your roof system that includes the failed roof membrane, wet insulation, and worst case scenario, deck replacement. This can be avoided by consistently making sure your drains and gutter system aren't clogged and that they are draining correctly."

Some of the consequences of clogged drains and gutters on a flat roof are:

• Water ponding - Clogged drains lead to water accumulation and ponding on the flat roof's surface. The excess weight can cause the roof to sag, crack, or collapse.

• Membrane damage - Flat roof membranes like PVC, TPO, EPDM, Built-Up-Roof Systems (BUR), Modified Bitumen, and most coatings are vulnerable to standing water. The constant submersion under water leads to blistering and degradation of your roof system over time.

• Rust and corrosion - Metal components like roof vents, AC units, pipes, or drain bodies will corrode faster when exposed to standing water on a flat roof. This can severely weaken the roof.

• Roof Deck/Structural Damage - Whether your deck is Steel, Concrete, Gypsum, Tectum, or Plywood, having to replace any of your building's decking is one of the most expensive repairs made to the structure of your building. Water can infiltrate your decking for years and by the time you are aware of the problem, deck repairs are a must.

• Mold and mildew - Flat roofs are prone to mold/mildew growth in areas of ponding water. This not only damages the roof surface but also poses health risks if the contamination spreads to the interior.

• Insulation saturation - On many flat roofs, the membrane lies on top of insulation boards. When water pools for prolonged periods, it can soak and saturate the insulation, rendering it useless. This causes problems with condensation from below.

• Ice dams - Frozen ponding water can form ice dams that force more water under the membrane and into the building. These types of leaks are unpredictable and different than a typical rain leak due to the damming effect of the ice build up.

• Voiding warranties - Most commercial roofing warranties require the roof to have proper drainage and a minimum of a 1/4" per foot of slope. Clogged drains leading to standing water may negate warranty terms.

KCCR stresses the importance of a comprehensive roof maintenance program. Whether the customer's roof system is brand new or the roof is past it's lifespan, the consequences of a clogged drain does not discriminate based on the roof's age. We have seen roof systems well within their lifespan ready for a full roof replacement due to the lack of proper maintenance. We have also seen roofs well past their lifespan that continue to out perform because of consistent roof maintenance. In summary, it is paramount to keep water moving and draining off of your flat roof system. To get the most out of your investment in your roof system, semi-annual maintenance to address clogged drains is necessary. If your roof drains or guttering need attention, please give us a call (816) 530-0188, or email Chris Alexander at [email protected].