Roof Drains: Mastering the Art of Roof Drain Management

Roof drains are essential for any roofing system. They are designed to manage water runoff and prevent moisture-related damage efficiently. They are necessary for keeping commercial and residential buildings safe from the damage that standing water can do over time, such as structural damage, leaks, and roof collapse.

Importance of Roof Drains

Roof drains serve several vital functions:

Water Management

Roof drains collect rainwater and snowmelt and direct it away from the roof surface. This is crucial for preventing water accumulation, particularly in flat and low-slope roofs, where pooling can occur. Managing water well helps keep the roofing materials in good shape and lowers the risk of leaks and damage to the structure.

Material Selection

Roof drains are typically made from durable materials such as copper, aluminum, or cast iron. Each material has its drainage advantages:

Copper

Known for its strength and resistance to corrosion, copper drains are often preferred for their longevity and aesthetic appeal. They are more durable and will only need to be replaced sometimes because they can handle bad weather.

Aluminum

Aluminum drains are lightweight and resistant to corrosion, making them a popular choice for many roofing projects. They work best in places that undergo freeze-thaw cycles and can be used in various climates. Aluminum drains are also cost-effective and easy to install.

Cast Iron

Cast iron is the most traditional and widely used material for roof drains. It lasts long and can hold heavy loads, making it perfect for business buildings. However, it is heavier and more prone to rust if improperly maintained. Due to their robustness, cast iron drains are often used in new construction projects.

Types of Drains

There are various types of roof drains, including:

Interior Drains

Installed at low points on the roof to collect water, these drains are connected to internal downspouts, allowing for efficient water removal.

Edge Drains

At the roof's perimeter, edge drains help manage runoff and prevent water from spilling over the edge.

Scupper Drains

These are openings in the parapet walls that allow water to flow off the roof. They are typically used in conjunction with other drainage systems.

System Components

A complete roof drainage system includes various components:

Strainers

These prevent debris, such as leaves and dirt, from entering the drainage system, ensuring that water can flow freely.

Outlet Pipes

These pipes carry the collected water away from the roof to the ground or a stormwater system.

Flashing

This material creates a watertight seal around the drain, preventing leaks at the junction between the roof and the drain.

Maintenance

The correct operation of roof drains depends on regular inspection and repair. Water collecting from blocked gutters raises structural damage and leak risks. Among the maintenance chores are system inspection, drain cleaning, and blockage checking.

Copper, Aluminum, and Cast Iron Roof Drains

Main Differences

The choice of material for roof drains significantly impacts their performance and durability:

Copper

1. Durability: Copper does not rust and can last decades without getting worn down.

2. Aesthetic Appeal: Over time, copper develops a patina that many find visually appealing, enhancing the overall look of the building.

3. Cost: While copper drains are more expensive up front, their longevity can make them a cost-effective choice in the long run.

Aluminum

1. Weight: Aluminum is lightweight, making it easier to handle and install than heavier materials.

2. Corrosion Resistance: Aluminum is naturally corrosion-resistant, especially in humid environments and varying temperatures.

3. Affordability: Generally less expensive than copper, aluminium drains appeal to projects on a tight budget.

Cast Iron

1. Strength: Cast iron is perfect for commercial and industrial uses. It is quite robust and can manage huge loads.

2. Longevity: With proper maintenance, cast iron drains can last many years, though they may require periodic repairs to prevent rust.

3. Cost: While typically more affordable than copper, cast iron drains can be heavier and may incur higher installation costs due to their weight.

Effect on Overall Aesthetic of Building

Each material contributes differently to a building's aesthetic. Copper drains are often favoured for their elegant appearance and the attractive patina they develop over time, making them a popular choice for high-end residential and architectural designs. Aluminum drains can be painted or finished in various colours, allowing customisation to match the building's exterior. Cast iron drains have a traditional, robust look that complements older buildings and industrial designs. The choice of material can enhance the property's overall architectural style and visual appeal.

Environmental Concerns

Each material has environmental considerations. Copper can leach into stormwater runoff, potentially harming aquatic ecosystems. However, its durability and recyclability can mitigate some ecological impacts. Aluminum is lightweight and recyclable, but the production process can be energy-intensive. 

Cast iron is highly durable and recyclable but can rust if not properly maintained, leading to potential water quality issues. Choosing materials with lower environmental impacts and ensuring proper maintenance can help address these concerns.

Weight and Structural Integrity

Copper drains are relatively lightweight but offer excellent strength and durability. Aluminum is the lightest option, making it easy to handle and install while providing good structural integrity. Cast iron is the heaviest of the three, offering superior strength and load-bearing capacity, making it ideal for commercial applications where durability is crucial. The choice of material can affect installation methods and the overall structural design of the roof drainage system.

Common Issues

Common issues vary by material:

Copper drains can develop corrosion if not properly maintained, particularly in environments with high acidity or pollutants. Additionally, due to their value, they may be susceptible to theft.

Aluminum drains can suffer from denting or deformation under heavy loads, and if not properly coated, they may rust over time, especially in coastal areas with salty air.

Extreme temperature swings or large loads can cause cast iron drains to break, and rust is a common occurrence. They might also require more regular maintenance to avoid obstructions from trash.

Peripheral vs. Interior Drainage Systems

Roofing has two main types of drainage systems:

Peripheral Drainage Systems

Design

These systems drain water from elevated interior roof areas to the roof's edges. Water is expelled through scuppers and rainwater leaders located on the parapet walls.

Advantages

Peripheral systems can effectively manage water runoff and are often easier to install in new constructions.

Disadvantages

As the drainage pipes are exposed to the elements, they can be vulnerable to freezing and deterioration from harsh weather conditions. Additionally, if not properly maintained, debris can accumulate and block the drainage paths.

Interior Drainage Systems

Design

Interior drainage systems collect water from various points on the roof and direct it to internal downspouts, which lead to the ground or a stormwater management system.

Advantages

This system is often more protected from environmental factors, reducing the risk of freezing and damage. Interior systems can handle more water without overflowing, making them better at controlling water flow, especially when it rains.

Disadvantages

Installation can be more complex, and issues with the internal downspouts can lead to water backup and potential leaks.

Maintenance of Roof Drains

Performing regular maintenance is necessary to make sure that roof drains work properly. Key maintenance tasks include:

Inspection

Check the roof drains often for leaves and dirt, which can get stuck in the system and prevent it from draining properly. Inspect the filters and outlet pipes for any signs of wear or damage.

Cleaning

Remove obstructions from the drain and filter to ensure water flows freely. This practice may involve clearing the drain bowl, washing away dirt and debris, and checking the outlet pipes for blockages.

Repairs

Inspect for signs of rust or damage, particularly in cast iron drains. Promptly repair any issues to prevent leaks and further deterioration. Signs may include replacing corroded components or resealing flashing around the drains.

Seasonal Preparation

Before winter, ensure that drains are clear to prevent ice buildup. In colder climates, consider adding heat tracing to prevent freezing. This proactive measure can help avoid costly repairs due to ice damage.

Professional Servicing

Engage a professional service for thorough inspections and maintenance, especially for larger commercial roofs. Professionals can provide specialised equipment and expertise to optimise your roof drainage system.

What if I need to avail services for roof drains?

If you're facing issues with your roof drains or need installation services, All Needs Plumbing can help! We offer a $0 callout fee and provide 24/7 same-day service to address your plumbing needs promptly. 

Additionally, we value our senior clients and offer a 15% seniors discount. If you're considering upgrading your hot water system, we also provide $150 off hot water systems. Contact us today at allneedsplumbing.com.au to ensure your roof drains are in top condition!