Why Your Roof Penetration is Leaking

August 9, 2022

Gas lines, piping, vents, and anything else that protrudes through the roof is known as a penetration. Boots and flashing seal the penetration, forming a barrier to prevent water infiltration. If your commercial roof is experiencing leaks at roof penetrations, we’ve outlined the likely reasons why below.

Poor or Improper Installation

If you contracted for your new/replacement roof with a roofing contractor who is trained and certified by the roofing manufacturer, it’s likely the flashing details were installed according to manufacturer and the National Roofing Contractors Association specifications.

The trouble often comes when you install a new pipe through your roof. It’s critical that you involve your roofing contractor in the installation of any new equipment or penetrations. An HVAC or plumbing tech isn’t also a roofer; they might create twice the work for your roofing contractor if they remove the roof membrane.

Hire a qualified roofing contractor that is licensed by the roof system manufacturer of the system you have installed. Put your roofing contractor in contact with the HVAC installer, cable company, etc. Together they can discuss the location of the penetration and appropriate flashing details. Then, schedule the work when both contractors are available, so your roofing contractor can do the roofing work to ensure a watertight seal.

Think you can DIY it? Think again. Improper (such as incompatible) materials and installation can inadvertently void the roof system manufacturer warranty. An experienced roofing professional may opt to use pitch pockets when other flashing methods would provide a better outcome (i.e. easier long-term maintenance, less likelihood of leaks, etc.). Who does the work matters. Always opt for trained roofing professionals to flash penetrations.

Lack of Maintenance

Pipes that vibrate can cause boots and field-wrap flashing to fail over time. Heat, freeze-thaw cycles, and intense UV can also lead to degradation. If flashing is pulling away, there’s an opportunity for water entry. Likewise, if your roof penetrations used pitch pans, beware of the pourable bituminous or polymeric sealant drying out or shrinking. Once the sealant becomes concave, it traps water and leaks are likely.

Regular routine inspections can check the condition of the roof system and integrity of penetration flashing. The best way to avoid problems is to catch them early. If your roof has a high volume of penetrations, have it inspected every three to four months. Avoiding roof maintenance is a good way to guarantee roof leaks.

Contact D. C. Taylor Co. today at 319.731.4118 for a roof inspection or to add a roof penetration.


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