How do you improve drainage on a flat roof?

A flat roof isn’t really flat, there is some slope to the roof, or it couldn’t drain. How does flat roof drain? here are drains spaced around the flat roof that flow into either gutters or to the street and storm drain. When these drains, gutters, or the downspouts are clogged, you have flat roof drainage problems.

After forty-eight hours after a rainstorm, if your flat roof has ponding water, there are flat roof problems with drainage not working properly. The following are ways you can fix the flat roof drainage:

  • Install Internal Drains: These are typically located in the center of the roof which are connected to piping that is installed under the roof. The water then drains down to the street sewage. These eliminate the need for gutters and downspouts, but they are easily clogged, causing flat roof drainage problems . This confirms why a flat roof needs monthly inspections.  
  • Downspout and Gutters: Gutters will guide water to the downspouts which transports the water off the flat roof. Again, monthly inspections are needed to make sure the gutters are clear, and the downspouts are connected and cleared and eliminate flat roof drainage problems before they happen. 
  • Scuppers: A flat roof will have rails along the rooftop where scuppers are positioned. A scupper is a flat roof opening around the parapet walls. This facilitates excess water drainage to the gutter system and to the downspouts.  
  • Leveling Compounds: A roof leveling compound can raise a roof surface that will allow water to flow to the scuppers, to the gutter, and out of the downspouts. Where ponding is deeper, tapered insulation can be used to fill the area with a filler material to fine-tune it. Professional application of a top coating will make the roof waterproofed.    


How do you unclog a flat roof drain?

When you have a   flat roof drain clogged, it doesn’t mean you need a professional roofing contractor, there are some ways of fixing a flat roof drain yourself. Roof drains aren’t unusual for flat roofing, but because they are out of sight, they are out of mind too. 

The importance of flat roof drains isn’t understood by everyone, but they are what keeps water off flat roofing. When they aren’t working, the lack of flat roof drainage can create many problems. Your maintenance team can do the following steps to clear the clog and get the flat roof drainage working right again: 

  • Be Proactive: Every month, a visual inspection is recommended, making sure to check the drains. During the spring and summer, critters are in the nesting mode, during the fall, leaves fill up the drain, and during the cold winter, water freezes in the drain, all causing the flat roof drainage not to drain. 
  • Plumber’s Snake:  Use a plumber’s snake, putting into the drain and see what you can pull up, the same process as with a bathroom sink. If the snake doesn’t pull anything up, it may have loosened a blockage the snake may be able to loosen it and the next step may be help clear the flat roof drainage. Feed the snake into the drain slowly. 
  • Water Pressure: After trying the plumber’s snake, or before trying the plumber’s snake, use a water hose with a high pressure nozzle. With the water hose fed into the drain, turn the water on full blast.. It may take a few minutes and keep pushing the hose further into the drain. Be ready for a clog to break free and clear the flat roof drainage working again.

If none of these methods work, you can call a professional commercial roofer to inspect the drains. They have tools and experience in these matters and may get your flat roof drainage problem fixed in a few minutes. They may also recommend replacing the drains. 

Do you need guttering on a flat roof?

Even a newer roof or recently replaced roof, are covered by a rubber membrane for leak protection. Even with that in place, professionals recommend that for proper flat roof drainage of a flat roof, should have a gutter system installed with downspouts.

Is pooling on a flat roof bad?

Yes, this is referred to as ponding in the roofing industry and will create a pool of stagnant pool that can cause various issues for the roof. Water sitting on a roof for any long period of time due to poor flat roof drainage can result with the following issues:

  • Roof Coating Damage
  • Roofing Membrane Damage
  • Roof Leaks
  • Possible Roof Collapse
  • Unwanted Plant Growth
  • Plant Roots Invading
  • Roof and Structure Weakened

Do flat roofs always leak?

No, you can have a flat roof for 30 years and not have any issues like leaks. This is all based on the roof being installed properly, proper care and maintenance, including monthly inspection, followed by needed repairs completed immediately. Call (931) 220-1728 today for flat roof repairs in Nashville, TN.

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