Does your home have a flat roof? If so, you probably picked it for all the benefits it has to offer.

Flat roofs aren’t only attractive; they’re also resistant to common roof hazards like high winds, hail, and animal damage. However, their flat construction also makes them the most vulnerable to water damage, so you need drains for flat roofs to help them last as long as possible.

With so many different drainage options on the market, it can be confusing to find the best system for a flat roof. In this article, we’ll detail five of the most popular drainage solutions for flat roofs.

But first, let’s consider why these systems are such a crucial part of keeping flat roofs in the best condition.


Why Are Flat Roof Drainage Systems So Important?

Sloped roof systems easily use the force of gravity to remove water due to their design, but flat roofs don’t have such systems. The risk of water damage multiplies as a result.

Water can pool onto the surface of flat roofs, leading to unwanted dangers such as:

  • Rotting wood
  • Leaks near roof features like vent pipes and the chimney
  • Accumulation of debris
  • Mold growth
  • Structural damage, such as a broken or caved-in roof

The risk of these dangers is exasperated the longer water sits on a flat roof. Therefore, they require a drainage system to help channel and remove the water.


5 Best Types of Drains for Flat Roofs

There are five popular types of drainage systems for flat roofs, and each one has its own advantages and disadvantages.

1. Inner (or Internal) Drains

Internal drains are also commonly called interior drains and work just like the drains in your sinks and bathtub. Drains are placed in areas where water accumulates the most, especially near the middle of the roof. They lead inside and then guide water away from the roof through an internal network of pipes and gutters.

Internal drains offer the following benefits:

  • Customizable design
  • Protects your foundation and walls from water damage
  • The building’s roof and walls protect the pipe system, reducing the risk of freezing or cracking
  • Can improve your home’s curb appeal thanks to their hidden design

There are also some disadvantages to consider. Interior drains are the most expensive drainage system option, and they can only be repaired by a professional roofing technician if damaged. It’s also easy for the pipes and drains to become clogged with debris, so you have to install strainers on the drains and regularly check them for buildup.

2. Gutters

Even though flat roofs may seem to be completely level, most do have very low slopes that still allow them to drain water. Therefore, gutters are the most cost-effective and popular type of drain for flat roofs. They use a system of open pipes at the edge of your roof to catch water runoff and move it away from your home through a downspout.

Gutters have many advantages, such as:

  • Universal design
  • Inexpensive
  • Easy to find and install
  • Effective at keeping water away from foundations and buildings
  • Protects doorways, walls, and window openings by preventing heavy downpours of roof water

Gutters do have a few disadvantages to consider. They are more vulnerable to damage from heavy debris, ice, and severe weather than other solutions. They can also pull away from fascia boards over time, resulting in unwanted damage and replacements.

3. Scuppers

Scuppers are one of the most effective drainage systems for a flat roof. Scuppers are large square openings along the edge of the roof that allow rainwater to drain off. They use conductor heads to direct water from the roof.

Scupper systems are often combined with downspouts or gutters to control where the water flows, directing it away from the foundation and building.

Scuppers offer many benefits, including:

  • Easy to maintain
  • Cost-effective
  • Enhanced aesthetics
  • Wide design nearly eliminates the chance of debris clogging

However, they also have their own disadvantages. The downspouts installed below the scuppers are likely to get clogged, so you have to check them regularly for debris. If your flat roof has a minimal or nonexistent pitch to guide the water to the edges, scuppers may be less effective. They can also be ineffective for melting snow and heavy rain.

4. Siphonic Drainage Systems

Siphonic drainage systems are most often installed in commercial buildings. These drains for flat roofs feature a series of drain openings that remove water at high speeds via a gravity-induced vacuum pump. They offer several advantages:

  • Free up space inside the building
  • Compatible with a green roof drainage solution
  • No need for electrical pumps since they take advantage of hydroponic pressure
  • Handle large volumes of water without being overwhelmed

However, they are more prone to blockage if they aren’t maintained regularly, and they may be erratic if installed in the wrong type of building.

5. Tapered Insulation

Tapered insulation is an easy way to remove water from a flat roof without spending thousands of dollars on structural overhauls. Installing panels of tapered insulation on the surface of a flat roof adds more slope to it, allowing water to drain off easily without pooling.

Tapered insulation offers several benefits, including:

  • Reduced heating and cooling costs
  • Prolongs roof life with an added layer of protection
  • Eliminates weight/load-bearing issues
  • Prevents water ponding and water damage

Tapered insulation does have some disadvantages. It can be a fire hazard if you don’t take proper precautions, such as installing fiberglass underneath it. It can’t support additional weight, so you’ll need to protect it from foot traffic damage with additional support structures.

It is also more vulnerable to the elements than other options, so you may need to cover it with a tarp or some other protective covering. All these additions, plus the cost of the panels, make it one of the most expensive drainage options.


Get the Perfect Flat Roof and Drainage System with Signature Roofing

You can protect your flat roof when you use the proper drain system for your home. Do you have questions about your flat roof or drainage system? Contact Signature Roofing today if you’re in the market for a new flat roof or need a drainage solution for your existing flat roof. Our knowledgeable, skilled specialists will happily help you with any of your roofing needs.