Effective Ways to Drain Your Flat Roof

Picture this: your home has a rooftop garden decorated with your favourite plants. It is the perfect place for simple walks. This is of course only possible when you have a flat roof. However, weather can damage it. Cracks, leaks and blisters are just a few of the problems commonly associated with this type of roof.  Does that mean you have to give up on your rooftop garden? Not at all. You can install a flat roof, but you will have to maintain it to avoid damage.

By the way, a flat roof is not entirely flat. It is in fact slightly sloped towards the drains so that water passes easily. These roofs are, no surprise, prone to clogging which can lead to leakage. If you choose to install a flat roof on your property, you should be aware of the various ways you can drain it. A flat roof might give you the option to make use of the space (say hello to your rooftop garden), but stagnant water can lead to severe damage and, eventually, collapse. Here are a few effective ways to drain your flat roof.

Ways to Drain Your Flat Roof

1. Inner Drains

Inner drainage is common to most commercial properties. Drainage pipes are placed under the roof or in the parapet wall to make sure that the space looks good and no pipes are visible. This drainage system is usually placed in the centre of the roof or where the slope is directed. These are most appropriate for large roofs.

Pros: The first thing to mention is that inner drains do not pose any visual hindrance. Moreover, they give you complete use of your roof. In fact, if constructed properly, this drainage type is best as the pipe has no contact with the roof or parapet wall. Even if there is leakage in the pipe, no damage is done to the property as water is drained away.

Cons: Maintenance and repair are costly as the pipes are under the roof. If they get clogged, this can result in water pooling and damage to the walls. Damaged, leaking pipes can also lead to casing damage and infiltration of water into your living space. When you install this type of drainage system, regular inspections are suggested.


Commercial gutter systems


2. Scuppers

This type of drainage consists of an opening in the side of the wall that carries water from the roof to the gutter or downspouts. Scuppers are usually combined with the latter so that water does not damage the walls. Use a collector head along with scuppers to avoid walls being affected.

Pros: Scuppers are comparatively less expensive than inner drains. Wide scuppers are best as small twigs and leaves do not get stuck and block the drainage system. Since you have a collector, debris does not block the flow of draining water.

Cons: Small scuppers clog easily. This is a disadvantage for buildings without space to fit wider ones. Downspouts are not optional with scuppers as the force of the water draining from the scupper can erode the property’s foundation.

3. Gutter

A gutter is also called a conductor pipe. It is basically a trough placed on the edge of the roof that drains excess roof water. In order to install it, the flat roof must have been properly constructed. You will also have to make sure that the slopes are well maintained, but that is easy with this type of drainage as you simply remove leaves and debris. The longevity of your gutters depends solely on the material you use; the most common are aluminum, vinyl and galvanized steel.

Pros: Gutters are affordable and an excellent choice to shuttle and control water flowing from the roof. It also protects the foundation of your home and prevents soil erosion.

Cons: Gutters have an open drainage system and therefore require regular cleaning of accumulated leaves, dust and dirt to avoid clogging. This maintenance is necessary to increase their longevity.


Siphonic roof drainage systems


4. Siphonic Roof Drain

A siphonic roof drainage system helps pass water faster than other roof drainage systems and is commonly used for flat roofs. This drainage system allows minimal numbers of outlets, and all the drains are connected to one single leader pipe. It works smoothly and has a scientific way to flush out roof water. Although the pipes are horizontal, there is no report of water clogging because of this. Siphoning moves the water out, so there is no need for a sloped pipe. This helps in coordination with other services. Say, you have HVAC equipment on the roof. If the pipes are sloped, like in a gravity drainage system, it will interrupt the placement of the HVAC equipment, therefore, taking up a separate place for the pipes.

Pros: The pipes are smaller in size, and there is less chance of water clogging as the water is siphoned away. This type of drainage system requires very little maintenance, and roof water easily passes through it.

Cons: The major complaint against siphonic roof drainage is that the small diameter of the pipes allows for blocking by detritus like leaves. System failure or operational damage can result if it is not regularly maintained.

Choosing a flat roof means installing a proper drainage system. There are four common options but which do you pick? Read through the pros and cons outlined here so that you choose the one that works best for your property. None of the drainage systems will work, though, when the slopes are not properly constructed. To avoid your flat roof becoming water clogged or leaky, supervise its construction and make sure your chosen drainage system is properly maintained.

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