How To Fix Standing Water On a Flat Roof?​

As a building owner, it is important that you know that despite their clean, modern appearance, flat roofs frequently have to deal with standing water. Standing water may not seem like much at first, but it may cause major problems, including leaks, structural damage, and mold and mildew growth. 

We’ll explain the reasons behind standing water, the dangers it presents, and the best ways to fix standing water on a flat roof in this blog post so you can safeguard your property.

Understanding The Problem: What Is Standing Water On A Flat Roof?​

Ponding, another name for standing water on a flat roof, occurs when water pools for more than 48 hours following a rainstorm. This happens as a result of improper roof design or drainage that hinders water movement. 

Although short-term pooling is typical, extended water can lead to major issues like leaks, the development of mold, and structural damage from the weight of the water. Preventing these problems requires routine maintenance, such as cleaning the drainage system and removing debris.

What Are The Consequences Of Standing Water On A Flat Roof?

Ignoring standing water on a flat roof​ can lead to serious issues:

• Structural Damage: Standing water adds weight, causing roofs to sag or collapse over time. This damages the roof deck and materials.
• Leaks and Water Damage: Water seeps through cracks, causing leaks that can damage ceilings and walls, leading to costly repairs.
• Deterioration of Roofing Materials: Constant exposure to water weakens materials and membranes, shortening the roof’s lifespan.
• Mold and Vegetation Growth: Standing water promotes mold and attracts insects, which can damage the roof and create health risks.
• Warranty Issues: Not maintaining proper drainage can void roofing warranties, leading to unexpected repair costs.

What Are The Common Causes Of Standing Water On A Flat Roof?

Here are some causes of standing water on a flat roof​ that you should always look out for:

1. Blocked or Ineffective Drainage

Flat roofs require effective drainage to avoid water buildup. When drains are clogged or too small, water pools on the surface, leading to potential roof and structural damage.

2. Faulty Roof Design

This issue is often made worse by poor roof design. Without a slight slope for water runoff, flat roofs create low spots where water collects, adding to the drainage problem.

3. Building Settlement

As buildings settle over time, uneven areas can form on the roof, creating dips where water gathers. These dips can make existing drainage issues worse, increasing the risk of leaks and damage.

4. Compressed or Wet Insulation

In addition to settling, heavy foot traffic or equipment can compress insulation, leading to an uneven roof surface. Saturated insulation further traps water, making drainage even more difficult.

5. Debris Buildup

Debris, like leaves and dirt, can obstruct drainage, preventing water from flowing off the roof. This blockage can worsen pooling, especially after rainstorms, causing long-term damage.

6. Improper Installation of Roof Features

Finally, poor installation of features like skylights, vents, or HVAC units can create dips or disruptions in the roof’s surface, further hindering proper drainage and allowing water to pool.

Professional Solutions For Fixing Standing Water On A Flat Roof

Is standing water on a flat roof a problem? Yes, it can lead to serious damage if left untreated. Here’s how to address it effectively:

#1. Roof Inspection by Experts

The first step is a professional inspection. Contractors assess the roof’s drainage system and materials to pinpoint the cause of standing water on a flat roof. This helps guide targeted repairs.

#2. Drainage System Upgrades

Once the issues are identified, upgrading the drainage system is often the next step. Adding more drains or enlarging downspouts enhances water flow, preventing future standing water on flat roofs. Keeping the system clear of debris through regular maintenance ensures ongoing effectiveness.

#3. Roof Repair or Replacement

If water damage is found, repairs are necessary. Sagging areas or damaged roofing membranes can be fixed or replaced with durable, water-resistant materials.

#4. Installation of Tapered Insulation

In cases where the roof lacks a proper slope, tapered insulation can help. This solution directs water toward the drains, improving drainage and reducing ponding, effectively addressing standing water on flat roofs.

#5. Creating Roof Crickets

To further improve water flow, roof crickets can be installed around obstructions like chimneys or vents. These structures redirect water toward the drains, helping to prevent standing water on flat roofs and ensuring better drainage.

#6. Advanced Repair Techniques

For persistent ponding, advanced methods like saddle construction may be needed. Saddles help redirect water around larger obstructions while adding waterproof membranes ensures extra protection.

#7. Fix Low Spots

Low spots can trap water, increasing the risk of standing water on a flat roof. These areas can be leveled with additional materials or leveling compounds, ensuring water flows toward drains and reducing the risk of ponding.

#8. Re-Pitch the Roof

When standing water becomes a consistent issue, re-pitching the roof may be necessary. By reshaping the roof with a better slope, water flows efficiently toward the drains. While this option can be costly, it provides a long-term solution.

#9. Add More Drain Lines

If the existing drains aren’t enough to handle heavy rainfall, adding more drain lines can increase capacity. Strategically placed drains ensure water is efficiently removed, preventing standing water on flat roofs during storms and heavy rain.

#10. Install a Sump Pump

For roofs with ongoing standing water, installing a sump pump may be the final solution. It removes water from low spots and directs it away from the foundation, offering added protection, especially in areas prone to flooding.

Are There Any Temporary Fixes For Standing Water On A Flat Roof?

Though nothing should replace professional solutions, if the damage is extensive and the professionals haven’t arrived yet, then you can try these temporary repairs:

1. Use Waterproof Tarps

Cover the area with waterproof tarps or polyethylene sheets and secure them in place. This stops rain from adding more water while you work on a permanent fix.

2. Apply Roofing Patches

If the standing water has started leaking into your building, use roofing patches or cement. It’s a quick fix to stop leaks temporarily until repairs are made.

Also Read: 5 Best Flat Roof Sealants Of 2024

How Much Can It Cost To Fix Standing Water On A Flat Roof​?

The cost to fix standing water on a flat roof depends on the issue’s severity and repair methods. Simple fixes, like clearing clogged drains, typically cost $100 to $800. More complex repairs, like adding tapered insulation or extra drainage, can range from $2,000 to $5,000. If the roof needs major structural repairs or a full replacement, costs can rise to $15,000 or more.

Standing Water on Your Roof? Rеnova Roofing & Construction Can Help You Fix It

Dealing with standing water on flat roofs is essential to protect your property. By knowing the causes and risks of ponding mentioned above, homeowners can take steps to prevent damage. Getting professional help ensures the right solutions are used to protect your roof and extend its life.
If your commercial property’s flat roof is flooded, Renova Roofing & Construction is here to help. Our skilled team specializes in commercial roofing services, offering everything from routine maintenance to complex repairs and replacements. We provide durable, weather-resistant solutions to protect your roof and ensure it remains in excellent condition. Call us today at (601) 647-3433!

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