Commercial Roof Drain Services - Showalter Roofing

Commercial Roof Drains and Drainage Systems

Commercial roof designs feature a slope or flat surface that requires a special drainage system. Showalter Roofing’s expert commercial roofers install, replace, and repair commercial roof drains and drainage systems. We work on various drainage materials to offer cost-effective, durable roof drainage solutions that fit your needs and budget.

What to Know About Roof Drainage Systems

Commercial rooftop drainage systems serve to release rainwater. Unlike traditional pitched roofs, which have a greater slope for positive drainage, commercial roofs are flat with a slight pitch. Therefore, they need advanced drainage systems to avoid water pooling, structural damage, and leakage.

Different Types of Drainage Systems

There are two drainage systems used today: gravity and siphonic systems. Gravity systems feature four sloping drain segments connected to an interior drain to carry water outside the building. These drainage systems are better suited for smaller commercial buildings with roof surface areas of less than 150m² and run on a grade. Larger rooftops may not drain sufficiently.

Siphonic systems, however, feature a baffle that lowers atmospheric pressure in the drain. The baffle allows the drain to pull water away faster than gravity alone – up to 100 times the speed. Siphonic drain systems can run on a flat surface with a collector pipe installed at the highest position and connected to vertical downpipes.

Most Common Commercial Drainage Materials

Drainage pipes and downspouts use different materials depending on the age of the building, type of structure, and budget. The most common drainage materials include

  • Cast Iron: Cast iron drainage pipes have been the most popular drainage material in history due to their weight and strength. However, it is expensive and clogs easily. Today, cast iron is a common material for drainage covers.
  • PVC: PVC has become a contemporary option because it’s affordable and easy to cut. While non-toxic and abrasive-resistant, PVC is weaker than other materials.
  • ABS: Acrylonitrile butadiene styrene is similar to PVC but does not offer the same heat or solar protection. Therefore, it’s not practical on rooftops unless covered with UV-resistant paints or pigments.

Any drainage material requires inner insulation to protect against freezing temperatures.

Drainage System Maintenance

Annual maintenance is crucial to improve the drainage system’s lifespan. Maintaining the drains once or twice a year prevents clogs. Preventative maintenance also helps you

  • Remove debris from the drains
  • Check for standing or ponding water
  • Monitor drainage speed
  • Ensure clamp rings, outlet drains, and dome strainers remain secure
  • Ensure downspouts direct water safely and efficiently

If you’re uncomfortable performing these routine checks yourself, the experts at Showalter Roofing know what to look for and have the tools, techniques, and experience to do it for you.

PVC drainage pipe in a commercial building.

Call Showalter Roofing for Drain Installation Services!

Call us at 630-499-7700 to schedule an appointment! Our roofers are always available to answer your questions or concerns. If we find anything wrong with the roof, we can also offer commercial roof repairs additionally to drainage services. At Showalter Roofing, we want every business owner to have a resilient, curb-appealing roof no matter what.

Makes Us

We know you have a choice.
Here’s how Showalter Roofing stands
out from the crowd by providing excellent work for our clients.


Our work speaks for itself. Our teams of commercial roofing contractors consist of highly trained roof maintenance specialists and our partnerships with leading manufacturers means that we install the best roofing systems available.

Customer Service

Our employees are committed to customer service, from our teams on the roof to executive management and everyone in-between. We are listening to our customers, driving our commitment to best in class customer service to ensure your commercial buildings remain in excellent condition.

Project Management

From pre-planning and project kick-off to completed job and project close out-our team works with yours on every detail. Working together is critical for mutual success, especially during a commercial roof replacement.


We maintain a database of our maintenance customers’ roofs and associated condition reports, that has us alert them when service life may be a risk or coming to an end.


We take safety seriously, from our crew training, to our on-site practices and team huddles.

Questions? We can help!

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The Word Is Out-Our Customers Love Us!

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We are extremely proud of the relationships we have built with our customers, and it is good to know they love us back!
Read why we are receiving more 5-star reviews than ever.

Roofing Industry Affiliations

When the time comes to repair or replace your roof, you can never be too cautious about the company you entrust with the job.
Choose a roofing contractor who can provide professional satisfaction and true peace of mind.