WHY FLAT ROOF DRAINAGE IS IMPORTANT

HERE FOR ALL OF YOUR ROOFING NEEDS!

One challenge with flat roofing is ensuring proper drainage.  Unlike other roofing types that are slanted or sloped to allow water to drain automatically, flat roofs need a built-in drainage system to help remove moisture and debris.  Poor drainage can lead to serious issues with flat roofing, from leaks to structural damage.  There are several drainage solutions available for flat roofing and it is important to consider the pros and cons of each system before making a decision.  

Flat roofing does not drain naturally like sloped roofs that can rely on the force of gravity to remove water.  If these roofing types are not fitted with a proper drainage solution, they will experience poor drainage which leads to the following issues:

• Pooling of water on the roof that can eventually lead to leaks or structural damage
• Accumulation of debris such as twigs and leaves
• Damage to the caulking and tar from debris buildup and pooled water
• Extra stress from ice in the winter
• Leaks near features of the roof such as the chimney or vent pipes

Leaving your flat roof without a drainage system will greatly increase the risk of these issues.  Fitting the roof with one of the following systems to ensure proper drainage will help keep it protected.

INTERIOR DRAINS

Interior drains work just like the drain in your shower or sink.  These drains are placed in areas of the roof that collect the most water and they lead the water into a system of pipes that is installed below the roof.  The water travels through these pipes until it is dispensed into a gutter or downspout at the side of the building.

True to their name, inner drains are installed within the roof or in the parapet wall—a small wall or railing around the edge of the roof.  This prevents visible pipes from hindering the building’s aesthetics.  Similar to the drains found in your sink and shower, an inner drain is usually located in the middle of the roof.  Because inner drains are generally best for large roofs, they are commonly found on commercial properties.

This drainage system has the following benefits:

• The walls and foundation are protected from water damage.
• The pipe system is protected by the roof and walls of the building which reduces the risk of cracking or freezing.
• Interior drain systems are customizable and can improve the curb appeal of your home or building.

Before deciding on an interior drain system for your flat roof, you must consider the following disadvantages:

• Interior drains are the most expensive flat roof drainage system.
• While this system is less likely to sustain damage, any damage that does occur must be repaired by a professional roofing technician. 
• The drains and pipes can easily become clogged with debris.  You must install strainers on the drains to prevent debris blockage and routinely check the system for debris buildup.

SCUPPERS 

Scuppers are a simple draining method for flat roofs.  These are large openings in the building’s outer wall that allow water to flow from the edge of the roof through downspouts installed directly below them.  The downspouts ensure water doesn’t damage the walls.  This may be the most efficient drain for flat roofs, as scuppers are easy to maintain and don’t tend to clog (as long as the opening is wide enough).

This is perhaps one of the most effective solutions for drainage for a flat roof. Using this system, large square openings are made along the edge of the roof that will shoot the water safely away from the side of the building.  There can also be downspouts installed directly below the openings that are used to catch the water and drain it away from the building in a controller manner similar to the gutters.

Flat roof scuppers also have several benefits.  In addition to being cost-effective, they are much easier to maintain, meaning you won’t have to clean them as you would gutters.  Those wide, large scuppers will rarely get clogged by debris, and a well-designed scupper can even enhance the overall aesthetic of the building, making it look a little bit nicer than traditional gutters would.

Like anything else, however, they do have downsides.  If you install the aforementioned downspouts, they risk getting clogged, and they will require regular checks for any debris build-up.  They can also be quite ineffective for heavier snowmelt and rain.  Also, scuppers tend to be less effective on a flat roof with no pitch to guide the water to the edges of the building.  The scuppers have to be somewhat cleverly designed to have the best overall effectiveness.

With scuppers, however, it is important to remember to check the downspouts on a regular basis for debris, since these are susceptible to clogs.  Scuppers can also be particularly susceptible to freezing, as their drain lines are exposed on the outside of the building. 

GUTTERS

Gutters are installed along the edges of the roof and direct water to a pipe or downspout.  As long as the roof is on the smaller side and tilts slightly toward the gutter, water should flow easily to the gutter.  This makes a gutter drainage system a simple and cost-effective option for smaller buildings. 

Be aware that gutters are completely open to the elements and therefore very susceptible to damage and clogging.  Debris like leaves and twigs can stick inside the gutters and cause considerable water backup. With regular maintenance and cleaning, however, gutters can be a great choice.

Edge Drains

This one works just as it sounds: they sit at the roof’s edge and collect the water there.  These are very similar to scupper drains in that the goal here is to prevent the water from running down the side of the building and causing any additional damage.  Edge drains are a simplistic way to divert that water from running down the side of the building, pointing the water to a predetermined destination so that it can drain safely away from the building without causing any damage.

SIPHONIC ROOF DRAIN

A siphonic roof drainage system uses a vacuum pump to remove water from a flat roof.  The gravity-induced vacuum is connected to a series of drain openings, drawing water away from the roof’s surface at a high speed.  This type of system is perfect for large roofs in areas that sustain heavy and frequent rain.  A major benefit of a siphonic roof drain is how fast it removes water from the roof.  It’s not prone to clogging, and the system requires little maintenance.  The pipes are small, helping to keep your roof clear and the placement of any equipment, like HVAC, unhindered. Because the pipes are small, however, it’s important to have them regularly cleaned and maintained to prevent blockage.  

Regular Maintenance and Inspection for Optimal Drainage

To ensure optimal drainage, you should regularly maintain and inspect your gutters and downspouts.  Gutters and downspouts can easily get clogged with debris such as leaves, twigs, and dirt.  When this happens, water cannot flow freely through the system, leading to water accumulation on your flat roof.  Therefore, it is important to clean out your gutters and downspouts on a regular basis to prevent any blockages.

Regular maintenance should include removing any debris from the gutters and downspouts.  This can be done by using a ladder and a scoop to manually remove the debris.  It is also a good idea to flush the gutters and downspouts with water to ensure that there are no remaining blockages.  Additionally, you should inspect the gutters and downspouts for any signs of damage such as cracks, holes, or loose joints.  If any issues are found, they should be repaired as soon as possible to prevent further damage.

Regular maintenance and inspection of your gutters and downspouts is crucial for optimal drainage on your flat roof.  By keeping them clean and free of debris, you can prevent water accumulation and potential damage to your roof.  Make it a part of your routine to check and clean your gutters and downspouts to ensure that they are functioning properly and effectively draining water away from your flat roof.