Once rainwater or melted snow collects on the roof, it must be transported away quickly by an efficient drainage system. Otherwise, the structure might suffer from potential water damage. Moisture can easily seep into roofing materials and find its way to interior parts of the building. They might also overflow to other areas like the property’s foundation, basement, and landscaping. In extreme cases, water accumulation can weigh down the roof and cause structural collapse.

Moreover, pooled water can promote vegetation or mold and mildew growth. Animals and insects might also use it as a source of drinking water or breeding ground. The presence of these elements is not only detrimental to the structure but to people’s health as well.

In New York state, a secondary or emergency roof drain is required if the structure has an elevated portion where primary drains might not be enough on their own to discharge water. According to the 2020 Plumbing Code of New York State, the inlet and outlet of the primary and secondary drain should be independent of each other.


There are two ways to drain water from the roof, by gravity or siphoning.

  • Gravity drainage

As the name suggests, this form of drainage relies on gravity to direct water flow. It is also known as a conventional roof drainage system since it has been widely used on residential and commercial buildings for years.

For commercial properties with flat roofs, this form of drainage is mainly recommended if the structure has a smaller surface area than 150 square meters per gully or drainage point. Larger volumes of water might not drain fast enough because air can enter the pipes, reducing the drainage capacity.


  • Siphonic drainage

Instead of relying on gravity, this form of drainage takes advantage of the lower atmospheric pressure created by restricting airflow within the pipes. The drain’s opening is fitted with a baffle that blocks out air. Consequently, water is sucked in and discharged faster.

This form of drainage is ideal for roofs with a larger surface area.

Furthermore, these two primary forms of draining are used in the following types of drainage systems.


Inner Drains

Most common in flat roofs, inner drains are often placed in areas where water collects quickly. Therefore, the roof’s center and other slightly pitched parts of the structure are ideal locations for this drainage system.

An inner drain works similarly to the drains found in bathrooms and sinks. The water funnels down a series of pipes underneath the roof until it reaches the outside of the property. Since the pipes are concealed within the building, it reduces the risk of cracking, freezing, or other forms of damage common to drainage systems that run along the property’s exterior. Sometimes, this drain system is used together with gutters or scuppers.

Because of inner drains’ construction requirements, they are more expensive to install and maintain than other drain systems. Property owners also must ensure that the drain opening has a protective screen to prevent debris from getting lodged inside the pipes.



Gutter drain systems consist of shallow channels or troughs placed at the edge of roofs that catch runoff and lead it to downspouts. This type of drainage is constructed to allow water to flow efficiently along the pipes, ensuring that it will not back up or overflow.

They are the most common type of drain systems, especially on residential properties, because they are inexpensive and easy to install. However, gutters require high maintenance to prevent debris buildup that can cause clogs, shifting, and other forms of deterioration.

To prevent most debris from entering the gutter, property owners can opt to install gutter guards. While taking out obstructions can be a DIY job, if the gutters require more thorough cleaning, it might be more practical to hire reputable companies that offer services for gutter cleaning in Suffolk County.



Also known as roof drain leaders, downspouts work in conjunction with other drain systems like gutters or scuppers. They are vertical channels attached to the building’s side that divert water to the ground and away from the property’s perimeter. Commercial properties typically require wider downspouts or multiple ones to support larger volumes of water.

As downspouts are responsible for ensuring water stays away from the building, they also require regular maintenance. Keeping them clean and clog-free enables water to flow efficiently. When signs of damage arise, they must be addressed immediately to prevent further deterioration.



A scupper is a channel or opening placed in terraces, parapets, or sidewalls that allow water to flow freely from the roof and into collector heads, gutters, or downspouts. It is usually used as a secondary drain system to help get rid of excess stormwater quicker. Sometimes, flowerbeds are placed beneath the outlet to catch the water.

This roof drain system is low-cost and easy to maintain. Clogs are typically not an issue with scuppers, especially if they have an adequate opening. To make the most of scuppers, they must be designed and installed correctly. They can also be customized for added architectural appeal.



When choosing the type of drain system for their roof, property owners must consider the structure’s size, design, pitch, drainage rate, and the construction materials available. Rainfall and snow volume are also other factors to keep in mind. Incorrectly sized and improperly installed roof drains can lead to costly repairs or replacements.

To help them narrow down their choices, property owners should consult with professional contractors. Well-experienced contractors handle various roof drain projects, including gutter installation in Suffolk County, NY, maintenance work, repairs, and replacements. They can inspect the property and make suggestions on which roof drain system is most efficient and budget-worthy.


Request a Quote at Long Island Roofing and Chimney Today!

Long Island Roofing and Chimney is a reliable and trustworthy roofing and chimney contractor on Long Island. With over 15 years of high-quality professional services, they are among the best companies to take care of roofing, chimney, gutters, and other home maintenance and improvement projects. Contact Long Island Roofing and Chimney today at 631-205-6177 (Suffolk County), 516-605-6108 (Nassau County), or click here to request a quote.