A Comprehensive Guide to Roof Drains: Types, Features, and Installation

When it comes to roofing, one critical element that often goes unnoticed is the roof drain. Roof drains play a pivotal role in safeguarding your building against water damage by efficiently channeling rainwater and preventing it from pooling on your roof. In this comprehensive guide, we will explore the various types of roof drains, their features, and how to properly install them to ensure the longevity and effectiveness of your roofing system.

Types of Roof Drains

Roof drains come in various types, each designed for specific applications and water flow requirements. Understanding the different types will help you make an informed choice for your roofing project.

1. Conventional Roof Drains

Conventional roof drains, also known as “vertical” or “downspout” drains, are the most common type. They are installed on the roof’s surface and use gravity to direct water through pipes to the drainage system. These drains are suitable for flat or low-slope roofs.

2. Scuppers

Scuppers are openings or channels in the walls or parapets of a roof that allow excess water to flow off the roof. They are particularly useful for flat roofs and can prevent water from accumulating around the roof’s perimeter.

3. Internal Roof Drains

Internal roof drains are designed to be hidden beneath the roofing material. They are often used in sloped or pitched roofs and are preferred for aesthetic reasons. These drains efficiently channel water through a network of pipes concealed within the roof structure.

4. Overflow Drains

Overflow drains are installed to prevent water from ponding on a roof. They are typically positioned at a specific height above the roof surface to allow excess water to drain away if the primary drain becomes clogged.

Features to Consider

When selecting a roof drain for your project, it’s essential to consider the following features to ensure optimal performance and longevity:

1. Material
Roof drains are commonly made of materials like plastic, aluminum, or copper. The material choice depends on factors such as climate, budget, and desired aesthetics.

2. Flow Rate
The flow rate of a roof drain is crucial to prevent water from pooling on your roof during heavy rainfall. Select a drain with a flow rate that can handle the expected water volume in your area.

3. Sump Depth
The sump depth refers to the distance from the roof’s surface to the drain’s opening. It’s essential to choose a drain with an appropriate sump depth to prevent water from accumulating on the roof.

4. Strainers and Guards
Roof drains can be equipped with strainers and guards to prevent debris from clogging the drainage system. Regular maintenance of these components is essential for optimal performance.

5. Freeze Protection
In colder climates, it’s crucial to consider freeze protection features in your roof drains to prevent ice buildup, which can cause blockages and damage.

Installation Guidelines

Proper installation is key to ensuring the effectiveness of your roof drains. Here are some installation guidelines to follow:

1. Locate Drainage Areas
Determine the areas on the roof where water tends to accumulate and where drains are needed. This should be based on the roof’s slope and local weather conditions.

2. Calculate Drain Size
Calculate the required drain size based on the roof area, expected rainfall, and the chosen type of roof drain. It’s crucial to choose a drain size that can handle the anticipated water flow.

3. Proper Sloping
Ensure that the roof’s surface is sloped correctly toward the drains to facilitate water flow. The minimum slope should meet local building codes and manufacturer recommendations.

4. Secure Drainage Pipes
Secure the drainage pipes, ensuring they are properly connected and sealed to prevent leaks. Use appropriate roofing materials and sealants to maintain the roof’s integrity around the drains.

5. Regular Maintenance
Proper maintenance is essential to ensure that your roof drains continue to function efficiently over time. Here are some maintenance tasks to consider:

  1. Clear Debris: Regularly remove leaves, twigs, and other debris from the drain strainers and guards. This prevents clogs that could impede water flow.
  2. Inspect Seals: Check the seals and gaskets around the drain for signs of wear or damage. Replace them as needed to prevent leaks.
  3. Clean Drain Lines: Periodically flush the drain lines to remove any accumulated dirt or sediment. This will help maintain proper water flow.
  4. Check for Damage: Inspect the physical condition of the drains, pipes, and flashing to ensure there are no visible signs of damage or deterioration.
  5. Winter Preparations: In colder climates, take precautions to prevent ice buildup. Use heat cables or insulation to protect against freezing.
  6. Professional Inspections: Consider scheduling regular professional inspections to identify and address any potential issues before they become major problems.

By adhering to a routine maintenance schedule, you can extend the lifespan of your roof drains and prevent costly water damage to your building.


Roof drains are a crucial component of any roofing system, ensuring that water is efficiently directed away from the roof’s surface. By understanding the various types of roof drains, their key features, and proper installation and maintenance techniques, you can protect your building from water damage and extend the life of your roof. Make informed choices when selecting roof drains, and always prioritize regular maintenance to keep your roofing system in top condition.

If you have further questions or need assistance with roof drain selection, installation, or maintenance, don’t hesitate to reach out to National Roofing Supply Inc. Our team of experts is dedicated to providing you with quality products and reliable service, helping you achieve a durable and efficient roofing solution.

Remember that your choice of roof drain can greatly impact the long-term performance of your roofing system. By taking the time to select the right type and ensuring proper installation and maintenance, you’re investing in the protection and longevity of your building.

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