Flat roofs are a popular option for homes and businesses because they look modern and are functional. One important part of keeping a flat roof in good shape is proper drainage. Unlike sloped roofs that let water flow off easily, flat roofs need a special drainage system to avoid water buildup and possible damage.
This blog post will cover the details of flat roof drains to help you choose the best option for your home.
What Is The Purpose Of A Flat Roof Drainage System?
For flat roofs, proper flat roof drainage is necessary to avoid water accumulation, which can result in leaks and structural damage. Flat roofs are not entirely flat, contrary to their name, and instead have a minor slope intended to channel snowmelt and rainwater toward designated drains. With drains, the amount of pooling water on a roof is reduced, benefiting the system overall.
With efficient drainage, you can ensure that your flat roof lasts as long as expected. Effective drainage also keeps insulation dry, which, therefore, impacts energy efficiency. Internal drains and scuppers are essential for this purpose, as without a proper system, flat roofs may have major issues, including leaks and foundation damage.
How Flat Roof Drains Work
Understanding how flat roof drains work is important for property owners who are trying to manage their roofs effectively. In order to help, we’ve provided a simple breakdown on how roof drains effectively remove water for flat roofs
Water Collection
When it rains, water collects on the surface of the roof. While flat roofs look flat, many are designed with a slight slope to help move water toward the drains,
Movement Toward Drains
As water builds up, gravity directs it to the nearest drain, helped by the roof’s gentle slope.
Water Disposal
Once the water reaches the drain, it flows through the drainage system’s pipes, either leading to a storm sewer or soaking into the ground.
Finding the Right Roof Pitch and Materials for Better Drainage
The subtle pitch on a flat roof is vital to avoid ponding, which can lead to leaks and roof damage over time. The slope should ideally direct water to the drainage system (scuppers, central drains, etc.) so that water moves efficiently off the roof.
When it comes to materials, flat roofs usually incorporate waterproof membranes like EPDM, TPO, or PVC. These materials help channel water toward drainage points, protecting the roof’s surface. Additionally, strategic elements like roof crickets—small, raised triangles along the roof, help direct water around obstacles like HVAC units or skylights, preventing pooling in hard-to-reach areas.
Pro Tip: Crickets and slight slopes around the roof’s perimeter ensure water heads for the drains instead of collecting in random spots. Regular inspections can help identify any changes in slope or dips where water might start accumulating unexpectedly
What Are The Different Types Of Flat Roof Drains?
To get the best for your flat roof, here is a list of different ways you can drain your flat roof with ease and zero complexity:
#1. Siphonic Roof Drainage
With a unique design that creates a vacuum effect, siphonic roof drainage systems efficiently pull water from the roof. By using baffles to prevent air from entering, these systems maintain low pressure in the pipes, boosting drainage efficiency. Siphonic systems can handle significantly more water than gravity-based systems, making them ideal for large flat roofs during heavy rain.
How Siphonic Roof Drainage Works
- System Setup: Pipes and fittings create a siphon effect, using baffles to block air from entering the drainage line.
- Water Flow: Rainwater is collected at low points on the roof and directed into the siphonic drains.
- Vacuum Process: Baffles help create a vacuum effect.
- Quick Drainage: Water is siphoned away quickly, helping prevent pooling and leaks.
- Maintenance: Regular checks keep the system free of blockages to ensure smooth drainage.
#2. Scupper Drainage
Scuppers, placed along the edges of flat roofs, serve as openings to drain water into downspouts or empty it out onto the ground below. Positioned at the roof’s lowest points, scupper
How Scupper Drains Works
- Location: Scuppers are placed at the edges or lowest points of the roof, often along parapet walls.
- Water Flow: Rainwater enters the scupper openings and is directed away from the roof.
- Drainage Path: The water flows into downspouts, avoiding roof buildup.
- Overflow Control: Scuppers can be paired with overflow drains for heavy rainfall management.
- Cleaning: Routine cleaning is needed to clear debris and ensure proper water flow.
#3. Central Roof Drains (Interior Drains)
Central roof drains, located in the center of a flat roof, connect to internal systems that carry water away from the building. Equipped with strainers to block debris, they are especially useful in colder climates by reducing the risk of frozen pipes. These drains keep the drainage system hidden, giving the roof a clean appearance, though they might require more upkeep than other types.
How Central Roof Drains Works
- Placement: Central drains are located in the center of the roof, where the slope is the lowest. Its downspouts are typically hidden within the structure.
- Water Collection: Rainwater flows into drains with strainers to filter out debris.
- Internal Pipes: Water is carried through pipes inside the building to an external drainage area.
- Effective Drainage: Water is efficiently moved away from the roof and the building.
- Maintenance: Regular inspections keep strainers clear and pipes functioning well.
Emergency Overflow Drains for Added Security
If you live in an area prone to heavy rain or storms, adding overflow drains to your flat roof is a smart choice. Overflow drains act as a backup when the main drainage system is overwhelmed. They work by directing excess water away from the building’s structure and foundation, reducing the risk of water damage during downpours.
Overflow drains can be strategically placed along the roof’s edge or through parapet walls. This extra system ensures that water doesn’t pool on the roof surface if the primary drains are clogged or unable to keep up. For added reliability, overflow drains can be connected to a separate drainage line, providing a completely independent path for excess water to escape.
How To Choose The Right Flat Roof Drain For Your Home
When selecting a drain for your flat roof, keep these key factors in mind:
1. Climate
Look at the typical rainfall and snowfall in your area to determine how much water your system needs to handle.
2. Roof Size
Larger roofs may need more drains or a more efficient system, like siphonic drainage, to manage water flow effectively.
3. Budget
Drain systems come at different price points, so choose one that fits within your financial limits.
4. Appearance
Think about how the drainage system will affect the overall look of your building.
Are You Dealing With Flat Roof Drainage Issues? OConnor Contracting Has You Covered!
Having trouble with your flat roof drain? OConnor Contracting is here for you! All kinds of flat roofing services like installation, maintenance, and repair are areas of expertise for our roofers. Our team of professionals is able to maintain your roof in order to keep it safe and leak-free. Whether it’s inner drains, scuppers, or siphonic drains, we can help! For an instant quote and help identifying the ideal drainage solution for your home, get in touch with us today at (716) 600-7663.
