Standing Water On Flat Roof

In the ever-changing roofing industry, flat roofs are one of the most common roofing designs in urban areas around the United States. Unlike gabled shaped roofs, flat roofs offer a unique form of advantages that gabled shape roofs don’t have. Since most triangular-shaped roof designs are meant to shed water, water damage is easily addressed. However, flat roofs are more prone to water damages since it has a more utilitarian design that’s meant for HVAC and other equipment. That said, flat roofs are quite susceptible to long-term damage from water.

Flat roofs are also susceptible to different forms of damages, most notably, damages from water and fluctuations in temperature. In most cases, these damages are usually caused by the improper way of designing and installing a flat roof. In reality, flat roofs aren’t entirely ‘flat’ but have a slope of around 0.5/12 to 1/12. One of the most causes of long-term water damages to flat roofs is standing water. If water is left to collect on your roof without any means of draining it, this could lead to leaks which can then become gateways to other forms of damages.

But before we can get into what are some of the best ways to prevent water from standing on your flat roof, we have to first look at what are the consequences of

Causes Of Standing Water On A Flat Roof

Knowing the cause of why there is standing water on our rooftop can help you formulate a plan in making sure that your roof is in the right condition.

There Is No Pitch

For most roofing contractors, a flat roof is not entirely ‘flat’ since it will usually have a pitch of at least 0.5/12 or 1/12. The reason for the low pitch is so that water can be directed to one side of the roof and filtered out towards the appropriate drainage systems. However, there are some contractors that overlook having a pitch for roofs. Having no pitch on a roof can trap water since it will remain stagnant on your roof.

Clogged Up Gutters And Pipes

Clogged gutters and drains are a common reason on why leaks form and water gets trapped on your roof. There are different causes of why gutters become clogged up. Most of the time, gutters become clogged because of debris that stuck on the pipes. It’s recommended that you do a thorough inspection of your roof for any source of debris. In most cases, dead leaves and fallen branches can be a cause for clog-ups.

Too Much Roofing Materials On The Edges

Naturally, if you’re going to place too many materials on the edges of your roof, it will serve as a barrier for water to drain out of. It’s best to install drains on the edges of your roof if ever you do have too much material on the edges.


Most people might overlook water as something harmless on your rooftop, but this could easily lead to problems if left unchecked.

Sagging Roof

One of the biggest tell-tale signs that your roof is on the verge of collapsing is that it’s sagging. Standing water can contribute to your roof sagging and warping if it’s not taken care of. Certain roofing materials do not bode well when exposed to extremely lower temperatures. If your roof is sagging, the only way to fix it is by having a roof replacement.

Leaky Roof

Water damages can seep through cracks and gaps on your roof’s surface which can lead to leaks. Once you do see leaks on your roof, it’s best to take action as soon as possible. Leaks can become gateways to more damages as water will erode the surrounding roofing materials near the leaks. Taking action on these leaks can help mitigate any future issues.

Organic And Fungal Growths

Water and moisture are the two main causes of why molds and mildews will form on a roof’s interior. If you ever see your ceiling sweating or having dark stains, then this is a tell-tale sign that there is organic growth. Molds, mildews, and mosses can damage your roof over time as it absorbs the minerals that make your roof durable.

Accelerated Deterioration

Normally, flat roofing materials will usually last 2 – 3 decades. The life expectancy of each roofing material will ultimately vary depending on the level of care and maintenance that’s being done. Having standing water on your roof can form rust on metal beams and rotting on wooden supports. This could lower the lifespan of your roof which could have lasted for 2 – 3 more decades.

Actions You Can Take On Your Flat Roof With Standing Water


The best course of action against standing water on your flat roof is by looking at what is the cause of the problem. If the standing water is mainly caused by a clogged up drainage system, it’s recommended to clear it up. If your drainage pipes are too narrow and can’t accommodate the amount of water that’s being flushed out, then you can widen it. In most cases, thick foliage close to your roof can also be a reason why your gutters are being clogged. Cutting down branches that is close to your roof can help make sure that debris does not fall on your roof.


If you’re not confident in your skills in clearing up clogged gutters, you can always call your local roofing contractor. Having a professional work on your roof can help mitigate any future damages that might happen on your roof. But if you are confident that you can address these damages yourself, you’ll need to consult your roofing contractor first on what’s the best course of action. You should take photos of the damages and the specific area that has water damages.