Any significant rainfall can produce standing water on a roof and water that has not evaporated 48 hours or more after a rainfall can become a problem. This is especially true for towns on the water that experience wind-driven rains like Bainbridge Island or Port Townsend.

Ponding water can pose a serious threat, particularly to flat roofs. It can lead to increased leaks and damage with roofing materials or even collapse the roofing deck.

Causes of Ponding:

1. Obstructed Drainage: Plants and dirt build up on the roof and in drains, blocking the escape route for rainfall.
2. Compressed Insulation or Membranes: A compressed membrane can have many causes or a combination of them, including age, heavy foot traffic, prior periods of ponding, heavy objects like HVAC units or other issues. Another major cause is wet insulation under the membrane.
3. Structural Issues: Some roofs have design issues, inadequate or poorly located drains, sagging with age, etc.

More significant issues require expertise. Work with a certified roofer to identify causes and rectify the stagnant water before it becomes an even bigger threat. Depending on the cause, solutions may include:

• Replacing damaged or low-quality insulation
• Diverting water with a small modification such as a cricket or tapering roof decks.


• Replacing or strengthening roof decking or other substructures
• Replacing the entire membrane

Regardless of what materials are protecting your roof, it’s best to walk the roof at least once or twice a year. During that inspection, make sure to clear any debris from the roof and pay close attention to drains to ensure that they are clear and functioning correctly. Even on roofs with no trees overhanging them, dirt and debris can collect. Although these are simple inspections, note that many insurance companies require them to be done by a licensed and insured contractor.

Another incentive for maintenance is to protect your warranty. It varies by manufacturer, but many warranties are voided if you do not perform basic maintenance. Be sure to check with your manufacturer to ensure you’re covered and determine what maintenance is required

If you have any questions about ponding or any other roof issues, contact Integrity Roofing & Construction today!

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