Remedies for Water Pooling on Flat Roofs (Tips + Hacks)


Ponding water might not be an immediate threat, but if it persists over time, it can begin to wear on the roofing membrane.

This leads to a decline in the membrane’s lifespan and can cause leaks, which can cause serious problems for the rest of the building.

Thankfully, there are a few different remedies that you can employ to resolve those ponding water issues on your flat roof before it starts leaking.


Water Pooling on a Rooftop (Blog Banner)

Keys to Stopping Water Pooling on a Flat Roof

  • Flush drains of debris like dirt, branches, and twigs
  • Add more drain lines
  • Use a roof plaster to direct water toward the drains
  • Install roof crickets
  • Perform regular inspections and maintenance

Flush Existing Drains

Like the drains in your home, drains on commercial roofs can eventually become clogged with debris. In more extreme cases, these serious clogs can lead to standing water becoming a mainstay on your roof.

To prevent debris buildup, try removing sticks, leaves, and any other rooftop debris from your building’s drainage system. Not only will this allow rain and melting snow to flow away from your building, but it will also prolong the life of your drainage system.

On its own, that debris seems harmless. But when it builds and builds, it can lead to various issues with your roof and the drainage system. Take those preventative measures, and you should see a longer life for your drainage system and your roof.


You can also hire a professional roofing service to come out and perform preventative cleanings on your drainage systems once or twice per year. That should be adequate to keep your drainage system clean and working optimally.

That bit of preventative maintenance might cost a little money in the short term but will save you a lot of time, money, and trouble in the long term.


Fix Low Spots

Despite their name, commercial flat roofs aren’t always completely flat. This is because subtle slopes on the surface of the roof can result from the installation process, weak spots in the roof, or a particular focus of debris or precipitation.

Additionally, qualified contractors understand how to slope a flat roof for drainage. These slopes are meant to facilitate drainage so that there is not a lot of pooling water on your roof.

It helps to remove that extra water off to the edges of the building, where an external drainage system lives, or to designated internal drains that will carry the water away.


One of the flaws of these low spots is that water ponding can occur quite easily. When that happens, the drains can clog with debris and fail to do their job. This leads to a buildup of water that can damage the roof membrane and eventually cause leakage.

A professional roofing contractor can fill those loose areas with a roof plaster to better direct water towards the drains.


Directing as much water as possible to your building’s internal or external drains is the goal.


Add More Drain Lines

If the current drainage system is having trouble effectively removing water from your flat roof, there are a few things that you can look into to help the process along. Though it comes with additional costs, adding additional drains is one of the most effective ways to address this issue.

Flat roofs, particularly those in areas with high precipitation, will sometimes need additional drains to properly clear the water from the roof. Unfortunately, most building owners don’t realize this until they see that water ponding becomes a substantial problem in the wake of a heavy storm.


Most professional roofing contractors worth their salt can install extra drain lines or even widen the existing drains attached to your building to direct excess water away from the rooftop.

Again, this is an extra cost, so most building owners will avoid this option. Still, it isn’t out there if there is a more efficient option.


Install Roof Crickets

When pooling on your flat roof, the water ponds in specific areas. These areas typically are near chimneys or around large vents. The best way to battle water ponding in these areas is to install roof crickets.

Crickets are ridged structures designed to divert melted snow and rainwater around roofing obstructions like chimneys and vents. Because of their positioning or design, those obstructions may have a naturally difficult time draining water on their own.

Adding crickets to these obstructed areas can also help when standing water is typically associated with transitions between roof areas. If you are experiencing ponding water in other areas of the roof, crickets might not be enough. It is important to know how to drain water from a flat roof.


If most of the standing water revolves around those obstructed areas, installing roof crickets can be the remedy you have been searching for.


Re-pitch The Rooftop

One issue your commercial building roof could be having when it comes to keeping away ponding water is that the pitch was not properly designed or installed during the initial process. All roofs need some form of sloping, even if it is subtle.

Without the right amount of slope, the water that builds during a storm won’t be able to drain and will, more often than not, lead to additional pooling across your flat commercial roof.


Re-pitching the roof might be costly, but it might also be the only way to solve consistent ponding issues on your commercial roof. It might be worth exploring other options first, but if you need to make the investment, there are far worse things to do with your money.

If you know what you are looking for, you can actually re-pitch the roof before a problem arises. Sure, noticing standing water is an obvious sign, but maybe you live in an area with many storms and want to take preventative measures.


Replace The Membrane

The membrane of your roof is the protective layer that keeps your roof safe from things like moisture getting into the roof, attic, or other areas of the building. When that moisture builds up in the structure of your building, it can cause substantial structural damage.

When the membrane becomes damaged – which can happen for various reasons, ponding water chief among them – it might be worth simply getting a new membrane for the roof.

Many membranes are designed to withstand ponding water, so it might be a blessing in disguise if you have to replace the membrane of your current roof with a more effective, modern version. An inspector will know how much ponding is acceptable on a flat roof.


You can also perform preventative maintenance to ensure that the membrane stands the test of time.


Inspect once or twice yearly to ensure the membrane is holding up and not worn or damaged in areas.


Compress Insulation

Compressed insulation, another potential cause of ponding water on your commercial roof, can be combated with frequent inspections. If that insulation is insufficient, your roof can also have serious issues.

Compressed insulation is generally caused by heavy roofing equipment resting on the insulation during installation. Repeated treading over the roof area can also cause indentations in the roof, which can lead to pooling.

You must ensure proper precautions are taken with the insulation and during any inspection processes. Damaging the roof through these processes is easy when some care could save you time and money


Keeping your commercial business roof working optimally is one of the most important aspects of owning that building. Your roof is the last line of defense against the elements, and it needs to work properly.

With preventative maintenance and a little attentiveness, you can keep your roof working the way it is meant to work. Don’t let ponding water become an issue for your business when you can use these tips to get rid of that pesky water.


Final Thoughts on Stopping Water Pooling on a Flat Roof

A flat roof has many benefits, but there is one definitive downside: pooling water. This is because flat roofs do not drain water as effectively as their pitched counterparts. Pitch roofs have a natural slope where the water can run down, draining off the roof.

Because these roofs don’t drain water well, they are prone to developing ponding water. Ponding water is defined in the roofing community as water that stands in a puddle on the roof for more than 48 hours at a time.

Several measures can be taken to prevent water from pooling on a flat roof, including flushing the drains, adding more drain lines, installing roof crickets, and more.