Feeney Roofing

What is Ponding? Why It Happens? (How to Fix Ponding on Flat Roof ? )

Why is There Ponding Water on My Flat Roof?, Flat roofing is known around the world and is commonly used for commercial buildings. Due to changing styles, flat roofs are becoming more popular with residential buildings. Homeowners that purchase flat roofs are typically unaware of for how different these systems are from sloped roof systems. Whether its for your home, garage or for commercial use, understanding a flat roof can benefit you and extend the life of your roof. 

Why is There Ponding Water on My Flat Roof?

Ponding is something that most people are unaware of since this does not occur on sloped roof systems. This occurs when water collects in puddles on the roof instead of draining off in a timely manner. Homeowners may believe that this water is harmless but as water continues to build, it can have a negative impact on the roof and your whole home. 

When it comes to owning a flat roof, it is important to understand what ponding is and how to resolve the issues that may impact your home. Maintaining the roof is important which is why early prevention and professional help is recommended. 

What is ponding?

Ponding occurs when water gathers on the roof for an extended period of time. the National Roofing Contractor’s Association (NRCA) considers ponding as water that has gathered for longer than 24-48 hours. Some water can collect in dips or around drains which should be monitored to see how long it sits. 

Why Shouldn’t Flat Roofs have Puddles?

Flat roofs should never hold water for extended periods of time. Small amounts of water can even have serious impacts to your home. Many factors of water retention can cause many different issues that may lead to major damage. Weight, erosion, plant growth, and leaks can all be factors that may lead to major damage.

Even small amounts of water can be heavy which can cause major stress on the roof trusses or other parts of the building. The roof has a specific weight limit that can be exceeded from one large pond to many small ponds that have not been maintained.  

Exposure to eater over long periods of time can increase the effects of environmental conditions that would damage your house. Water molecules can erode roofing materials and can increase damage from the sun. Winter can also cause ponds to freeze which produces ice that can damage your roof. Erosion due to ponds does occur and can cause your roof to fail. 

Ponding typically allows for the growth of many plants, algae, mosses, and lichen which has many impacts to your roof. Vegetation does not only increase erosion, but it can stain and grow into your roof system. Vegetation and water can also increase animal inhabitancy which can cause major issues to your roof and inside your home. Insects can even be attracted to water and vegetation that can then cause infestations. Vegetation can be a huge issue for homeowners that may simply become a nuisance that impacts the quality of your home and your quality of life in it. Pooling water can even be a breading ground for many insects including mosquitos.

Ponding typically causes roof leaks in many ways. The weight of the water alone can split your roof and cause it to cave in. Water can also penetrate the structure slowly causing rotting before the issue has been found. This water can also freeze which can damage the roof or reduce the life expectancy. 

Ponding can cause severe damage which is why understanding the issue is important and following the right steps to address it is important. Avoiding damage is the best way to save money and reduce unwanted stress. 

Why Does Ponding Happen?

There are many reasons why ponding can occur and why it continues to get worse. These include:

  • Improper installation: A flat roof isn’t perfectly flat, and it must be installed on a slight pitch to allow for positive drainage of the roof. The slope should gently guide water towards the drains and If it slopes away from the drains instead or has an inconsistent slope, you may get ponding at the lowest points on the roof. 
  • Drainage issues: Clogged or slow-moving flat roof drains can create ponding issues. Some flat roofs are so large that they need siphonic drains to move water quickly. On residential roofs, a more common issue is the connection point between flat and sloped roofs. Improper installation of this connection can result in poor drainage and ponding issues.
  • Compressed insulation: Some flat roofs are not built for foot traffic or for the storage of heavy items. When these roofs are used for that purpose, the insulation can compress, and this compression can create a low spot which may naturally collect water. The weight of the water can continue to increase this problem over time. You should not store objects or place heavy decoration on your flat roof unless the roof is specifically designed and protected to accommodate these loads.
  • Dips near roof features: Certain roof features, such as skylights or plumbing vents, may have been installed with small dips that allow for ponding and become worse over time. They can also be installed with improper connections to the flat roof. It is essential to get an experienced roofing professional to install these features and their flashing to prevent this problem.
  • Structural issues: Buildings settle over time, and sometimes this settling can create problems with the slope of the roof and cause ponding.
  • HVAC leaks: Sometimes HVAC equipment that is installed on the top of the roof causes ponding because it is too heavy and creates a dip in the roof. The ponding water may also be normal condensation or an abnormal leak from the air conditioner itself. The water may be slowly draining but resupplied by the machinery. In this case you will need an HVAC professional to fix the equipment’s leak or reroute the normal condensation.

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How to Fix Ponding on a Flat Roof

Removing water from a flat roof is only a temporary fix which will not prevent any future issues from occurring. You will need a professional to help you fix ponding on your flat roof. There are several flat roof ponding solutions that your roofer may discuss with you. Which one is right for your roof will depend on what’s causing the ponding and the specifics of your residential roof system. These fixes can include:

  • Conduct the Roof Inspection: When you call roofers about your flat roof’s ponding, the first thing they should do is inspect the roof to discover what is causing the ponding. Your roofers may also need the help of an architect or structural engineer if there has been structural damage to the home. Your roofers should explain what the problem is and give you a quote before they begin work. 
  • Fix Structural Issues: When ponding has caused structural damage to the building, that damage should be addressed first. Your roofers may need to work with structural engineers or architects to make a plan to address structural issues.
  • Fix Slope Issues: If your roofers found that your previous roofers installed the flat roof without the proper slope, they may need to replace the entire roof. Unfortunately, this is one of the more expensive and time-consuming solutions to ponding, but if the roof is improperly sloped, you may have no other choice to solve the ponding for the long-term.
  • Fix Drainage Issues: When the drains are the problem, your roofers have a wide variety of solutions available to them. It may be that you need to add in a new drain or change the drainage system so that it can accommodate more water. If the drain is frequently getting clogged, your roofers may recommend a better drain screen, or for you to get the roof cleaned more regularly. In cold climates, meltwater from snow may freeze in the drain. In this case, your roofers may recommend an electric cable to re-melt any ice in the drain or they may suggest a new schedule for snow removal that may reduce ice development.
  • Fix Low Points on the Roof: If your roof has a correct slope overall but has developed low points from improper installation, misuse or damage, your roofers can correct those specific low spots on the roof. They may install a roof cricket to redirect water away from a low point. They may use a flat roof puddle filler to bring low points back up to the appropriate level or if the low spot is near a roof feature or a drain, they may need to reinstall the flashing on that feature.
  • Fix Other Roof Damage: Once they have fixed the underlying cause of the ponding, your roofers should also be careful to replace any materials that were damaged by the ponding. They may need to replace sections of your cap sheet that were constantly exposed to water or replace insulation that was compressed under the weight of the water, or any other part of the roof.

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The Importance of Getting Professional Help with Ponding

Ponding can be extremely detrimental to your roof and if not properly addressed, can continue to get worse, cause roof leaks, early onset of roof decay and in turn, damage your entire home.

A professional roofer should be able to get to the root of your ponding problem, resolve it, and help you understand how you can avoid this problem in the future. At Feeney Roofing, there are experts that can share expertise and maintenance to help with every homeowners needs.