HOW TO DRAIN YOUR FLAT ROOF

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Your 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, but stagnant water can lead to severe damage and, eventually, collapse.

One of the reasons for the rise in popularity of flat roofs is their functionality.  Besides being more resistant to adverse environmental conditions like strong winds, you can also use it as your relaxing or outdoor living space.  However, despite the multi-functionality that comes with it, a flat roof can pose a few challenges.  The main one is its drainage system.  Pools of water can accumulate on the roof when it rains, which can cause stress on your roof’s structural support.  As a result, the water and other debris can quickly damage your roof, causing costly repairs.

Therefore, installing necessary drains on your roof to direct the water away from it is crucial.  Various systems can help you achieve this.  For instance, using a gutter system is one of the preferable drain systems by constructors.  Below are a few effective ways to drain your flat roof.

GUTTER SYSTEMS

As mentioned above, the gutter system is one of the most commonly used drains for a flat roof. Most contractors install gutters as part of the building’s plan. However, if you find your home doesn’t have an efficient roof drain, you can consider installing gutters.

Moreover, construction professionals consider gutters more cost-effective. One of the main reasons is that they don’t need you to carry out extensive roof modification to install them.

On the other hand, most flat roofs aren’t completely flat. Any roof that has an angle of fewer than 10 degrees is considered flat. Therefore, your roof may typically have a slight slope to it. This means when it rains, the rainwater flows by gravity from the roof.

Meanwhile, gutters would aid in directing water flow along the roof’s edges and away from the structure. This helps control its flow towards the central drainage system on the ground level. Thus, you can avoid erosion around your building’s foundation. The gutters also prevent water from splashing on the window and door openings.

If you’re considering the gutter system, it’s essential to know that it would require regular clearing of debris. This is a maintenance process to prevent clogging and increase its lifespan.

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 materials used 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.

Internal Drains

Other roofing experts also call these inner or interior drains.  As the name indicates, these drains aren’t visible from the outside, unlike gutters or scuppers.  Internal drains are typically installed across the roof and have drain pipes hidden underneath.  They lead the water away from the top and towards the primary drainage system on the ground.  Each drain connects to its pipeline, which directs the flow of water.

Moreover, internal drains have a screen on the roof flow that prevents debris from entering the drainage system.  This helps prevent clogging along the drainage line.  Depending on its size, you can install one or more internal drains on your roof.  However, it’s recommended to ensure the drains’ placement is strategic to avoid water pools.  Even though this type of drain is slightly more expensive, it can last longer.  It’s because they’re protected from adverse weather conditions by the building’s structure.

Additionally, internal drains don’t affect your structure’s visual appeal.  However, it’s essential to ensure that no debris gets into the drains.  The reason is that if they clog, you may need to get a roofing professional to unclog and repair them.

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 center 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.

Scuppers

Although they’re almost similar to gutters, their functionality differs.  While gutters collect and direct water from the roof, scuppers direct the water from the flat roof. In addition, they aren’t installed on the entire roof’s edge.  On the other hand, it’s important to note that scuppers work best with other drain systems.  You can use scuppers with gutters or tapered insulation.  Most roof experts recommend tapered insulation as it helps direct water pools toward scuppers.

In addition, scuppers don’t get clogged easily as they’re mainly wide by design.  However, they protrude from the building’s wall, hence, they can easily be destroyed by severe weather. Thus, if you live in a location with frequent strong winds or storms, it may not be ideal.  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.

 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.

Conclusion

Any of these systems will effectively divert water from your flat roof, provided it is installed correctly and properly maintained.  It’s important to strongly consider each drainage system’s pros and cons before you make your decision, including cost, durability, and maintenance requirements.  When in doubt, consider your building type and location to help you determine the best drainage system for your flat roof.