Addressing Ponding Water: Solutions for Flat Roofs

Flat roofs are popular for their sleek look and cost-efficiency, especially on commercial buildings and modern homes. But one major challenge that comes with them is ponding water—the pools of water that remain on your roof for more than 48 hours after rain.

While it might seem harmless at first, ponding water can lead to serious issues like leaks, structural damage, and premature roof failure. Let’s break down why it happens and what you can do to solve it.

Why Ponding Water Happens on Flat Roofs

Unlike pitched roofs, flat roofs don’t have much slope to help water run off. Over time, several factors can cause water to accumulate:

Improper roof slope or design
Clogged or undersized drainage systems
Roof sagging or low spots
Damaged or compressed insulation beneath the roofing membrane

Risks of Ignoring Ponding Water

Leaving ponding water on a flat roof unchecked can significantly shorten the roof’s lifespan. Over time, the standing water can cause the roofing membrane to deteriorate, making it more vulnerable to tears and cracks. As the material weakens, it increases the likelihood of leaks developing, which can lead to water damage inside the building. Moisture from the pooling water can also encourage the growth of mold and mildew, affecting indoor air quality and posing health risks. In addition, water that seeps beneath the surface may begin to rot the roof deck, compromising the structural integrity of the entire roof system. In extreme cases, the added weight and ongoing water damage can place significant stress on the structure below, creating a serious safety concern if not addressed.

Effective Solutions for Ponding Water on Flat Roofs

Here are proven ways to fix and prevent ponding water on your flat roof:

1. Improve Roof Drainage

Ensure your flat roof has an effective drainage system. This might include:

Installing or clearing scuppers and gutters
Adding internal drains
Using tapered insulation systems to promote slope

2. Install Crickets or Saddles

These are small, raised areas that direct water around HVAC units or other obstacles on your roof, guiding it toward drains or scuppers.

3. Use Tapered Insulation

If your roof has noticeable low spots, tapered insulation can be installed during a repair or replacement to create the proper slope and eliminate pooling areas.

4. Apply a Reflective Coating

While not a cure-all, a reflective roof coating can help protect the membrane from UV damage and reduce surface temperature, which slows deterioration.

5. Schedule Regular Inspections

Routine roof inspections help catch ponding issues before they lead to major repairs. We recommend at least one inspection per year, and after major storms.

When to Call a Professional Roofing Contractor

If you see standing water on your flat roof, it’s best to get a professional assessment. DIY solutions can cause more harm than good, especially when it comes to roofing drainage systems. At Horizon Roofing & Exteriors, we have years of experience dealing with flat roof repair, drainage upgrades, and ponding water solutions in both residential and commercial settings.

Final Thoughts

Ponding water isn’t just a cosmetic issue—it’s a sign that your flat roof needs attention. Addressing it early with the right solution can save you thousands in future repairs and protect the structure of your building.