Understanding Roof Drains: How They Work and Why They Matter

If you own a commercial property, you need to understand roof drains: how they work, and why they matter. A properly functioning drainage system will prevent leaks and keep your building safe and dry.

There are several types of drain systems used for flat and sloped roofs. Understanding how they work can help you choose the right one for your needs.

External Drains

Roofs come in all shapes, sizes, and styles, resulting in various drainage needs. Understanding your roof drain system can help you identify potential problems, take preventative measures to keep the water off your roof, gutters, and walls, and ensure a healthy, leak-free building. Inspect your outside drains regularly and remove any debris that is clogging them. This can be done using a flashlight to see the dark underground holes or pipes better and carefully remove any items present without damaging the pipes themselves. Once the drain screen is removed, run a hose down the drainage system to flush it out and remove any dirt and debris clogging it. This is an excellent way to avoid costly repairs and maintenance. It is good to check different websites and companies for roof drainage Stamford, CT, to understand the different roof drain systems.


Gutters collect rainwater from the roof and direct it to a downspout that directs it away from home. If the gutter system is clogged, water will overflow and collect next to the home’s foundation. Gutters and downspouts should be inspected regularly to ensure they are working properly. They should also be cleaned to remove clogs and weeds. A properly-sized gutter system catches rainwater as it falls and then redirects it to a downspout that conveys it to a drainage system or extension that relocates it away from the foundation.


Downspouts work with gutters and scupper systems to carry water off the roof and away from your home. They keep rainwater from running over your siding, foundation, and other exterior walls, preventing mold, mildew, and moss growth that can lead to discoloration, wood rot, and leaks. It’s important to remember that your downspouts should be designed and installed in such a way as to direct the majority of the runoff from the roof to the ground. If anyone downspout drains significantly more surface area of the roof than others, it could result in standing water on the ground and accelerate erosion.

Internal Drains

Interior drains are a common drainage system for commercial buildings. They are positioned underneath the roof and in the walls to direct water away from the building effectively. They typically feature a strainer to catch debris and avoid pipe blockages. They can also be customized to the project and are aesthetically pleasing. These systems work with gravity to move water off the roof of a commercial building, especially flat or low-sloped ones. Differently sloped segments all flow to one internal drain, leading to an underground system that carries water to the ground below. While these drains are much easier to maintain than a gutter and downspout combination, they clog occasionally. It’s always a good idea to have these pipes inspected and cleaned regularly to prevent blockages from occurring.