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Which Drainage System Is Suitable For Your Commercial Flat Roof?

Gravity doesn't usually move water from your commercial flat roof to the ground. So, you'll need a drainage system to prevent leaks or water damage. Commercial roof construction companies offer various flat roof drainage solutions, each with pros and cons. Read on to explore the four drainage systems.


With scuppers, commercial roof contractors install a large square opening along the edge of your commercial roof. The drainage shoots water away from your commercial flat roof. The roofers also install downspouts below the scuppers to control moisture in a way similar to gutters. 

Scuppers are usually simple, cost-effective, and have low maintenance needs. You can also add architectural appeal to your roofline with custom scuppers. Large scuppers also rarely get clogged by debris. The con is that if you prefer smaller scuppers, you must take extra caution to prevent blockage.


As the water falls off your commercial flat roofs, gutters catch and divert the rainwater into a downspout. The system dispenses water to a safe distance from your building. As a result, your siding, windows, and foundation stay safe from water-related damage.

Gutters are widely available, inexpensive, and easy to install. The downside, however, is the frequent cleanup you need to remove debris. Otherwise, the buildup could block water flow or overflow and run down the side of your building. 

Interior Drains

Commercial roof contractors use drains in commercial flat roof areas where water is likely to build up. The drains lead rainwater through pipes installed below your roof. Often, each drain has a filter or screen that keeps debris outside the system.

Your walls and roof protect the pipe system of interior drains from damage by the elements. As a result, the chances of cracks or freezing decline. The system is also highly customizable, and you can get your desired type. The downside, however, is that the nature of installation makes interior drains expensive.

Tapered Insulation

Roofers can add more slope to a flat roof to drain off water. Fortunately, they can accomplish the slope without a major structural overhaul. Tapered insulation comes in handy to create the slope while improving your building's energy efficiency.

Tapered insulation comes in easy-to-install panels and addresses water pools on your roof. Nonetheless, you'll need to combine the solution with at least one other drainage system discussed above.

Your location and building can help determine which drainage system fits your commercial roof best. The ideal solution is one with the correct amount of pitch to drain much rainwater naturally. Also, consider the pros and cons of each to ensure you can handle the challenges.

Contact a local commercial roof contractor to learn more.