The Three Different Types of Commercial Roof Drains

In many cases, residential and commercial roofs share a number of similarities, such as many materials; however, in other ways, they can be very different. One of these is very apparent; most commercial roofs are flat.

This means that unlike the sloped roof used in most residential structures, rain cannot simply slide down into a gutter to be output below. This requires different drainage solutions in order to prevent moisture pooling, thus resulting in a buildup of mold and mildew.

There are three primary ways to do this, and we will take a look at each of them here.

Interior Commercial Roof Drains

Interior roof drains are pretty simple and work similarly to the drains in your home’s sinks. The drains are strategically located where most of the water naturally gathers and feeds it into pipes that pass through your building and into a gutter. There it drains out onto the street below.

Pros of Interior Roof Drains

  • Pipes are held inside the roof and protected from damage caused by weather.
  • Drains are easily customized to fit in with any taste or style.

Cons of Interior Roof Drains

  • These are not the cheapest option for commercial drains.
  • Interior roof drains are not easy to work on and require a professional to perform repairs.
  • The drains require effective filters; otherwise, they are vulnerable to debris buildup and clogs.


Just like with residential properties, gutters are a common solution for drainage on commercial properties. This is a low-cost solution that catches water as it flows off of the side and directs it through a downspout to wherever the owners choose.

Pros of Gutters

  • Highly affordable choice
  • Easy and affordable to repair and clean

Cons of Gutters

  • Gutters require regular cleaning to prevent clogs due to their exposed tops and downspouts.
  • They are vulnerable to damage from harsh weather.


Scuppers are openings protruding from the roof’s edge allowing water to drain out the side away from the building. These can drain into a downspout to direct water wherever you choose.

Pros of Scuppers

  • Scuppers are a highly affordable option.
  • They are much easier to maintain than either gutters or interior roof drains.
  • Scuppers can be built in virtually any size, making it possible to design one large enough to prevent most clogs.
  • These can be designed in many shapes and designs.

Cons of Scuppers

  • When designed in coordination with a downspout, it can easily lead to clogs.
  • Often design plays a large role in how effectively the scupper works.

Final Thoughts

These are the three types of gutters most commonly installed on commercial buildings, and in many cases, any may work. However, the optimal drainage system for a given commercial building also may depend on the particular situation. It is always a good idea to contact a professional roofing contractor in order to determine the best drainage for your building.

Contact Us

If you need advice on the right drainage system for your commercial building or to schedule repairs or installation, contact North Shore Roofing. Our fully licensed and bonded professional roofers have more than thirty years of experience helping commercial and residential clients. Call us at (978) 977-3816 and connect with us on Facebook.