How Does a Flat Roof Drain Water?

August 12, 2022 12:00 am Published by Leave your thoughts

Are you wondering how do flat roofs drain water? Flat roofs can make any building unique, whether a cityscape full of towering office buildings or a home in your neighborhood. They are resistant to severe weather, durable, and can turn any roof into an outdoor living space easily. However, you may be wondering where all the rain and snow goes from what these flat roofs use to ensure that the water is diverted properly from the building.

Flat Roofs and Water Drainage

Flat roofs don’t have the advantage of slope and gravity to remove water. This is why they need to use a drainage system to assist in getting the job done. Several drainage solutions work well with flat roofs, each with its own set of pros and cons.

Interior Drains

When it comes to flat roof problems with drainage, interior drains are the first. This type of drainage system is typically located on the roofs of larger buildings. However, they can be used for residential homes as well. You may want to think of them as the drain in your shower or sink. They consist of an interior system of pipes located below the roof. They are used to carrying water away from the foundation of the home.


Gutters are the most commonly used drainage system when it comes to flat roofs. Gutters catch rainwater and turn it into a downspout, which then carries it away from the foundation. They are inexpensive and universal and are the easiest drainage systems to find and install. Gutters also help to prevent water from pouring off the roof when it rains heavily, thus protecting doorways, walls, and window openings.


These are basically large square openings in the curbs or outer walls located along a building’s roofline. These openings allow water to flow from the side of the building. It is typical for scuppers to be installed with downspouts right below the openings to catch water and carry it away from the building.

Scuppers are the perfect choice for draining water efficiently from a flat roof. They are cost-effective and easy to maintain. You rarely have to worry about clogging. They can also enhance the architectural appeal of any building. However, if you have downspouts installed below the scuppers, you will need to have them checked frequently since they can clog. Additionally, scuppers may not be as effective on downspouts and snowmelt.

Final Word

These systems will work well to carry water from your flat roof if installed and maintained correctly. You should also consider each drainage system’s pros and cons before making your decision, such as cost, maintenance, and requirements. If you are ever in doubt, you can consider your building location and type, which can help you determine the best drainage system for your flat roof.

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