Leaks in membrane roofs

Artiom Komardin, CSO 23 May 2019 Kategoria: Water on the roof
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A fairly common failure of membrane roofs (but also felt roofs) is leaks. These are generally caused by leaks in the roof covering. We explain what causes them, what they do, and how to prevent them.

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The first cause of such faults as membrane roof leaks are incidents of executive or technological nature. It is mainly the lack of proper welding on laps or improperly made flashings at skylights. Such faults usually occur during the first year of use and are generally repaired under the building work warranty.


The second group of leaks is related to the use of the roof and its natural wear and tear. They cannot be avoided, and every manager of a large property has to react to leaks several times a year (sometimes even more often). The causes of leaks during operation are very varied: mechanical damage during snow removal or service work on the equipment on the roof. It is not uncommon for the membrane to be damaged by feeding birds. This happens especially on roofs of buildings located near the sea and bodies of water, rubbish dumps or during autumn and spring bird migration.


Water itself getting inside a hall is a major nuisance as it can destroy goods or stop a production line. In commercial facilities, it puts visitors at risk of falling on slippery floors. It is therefore important to quickly identify and remove the cause – i.e. to “patch” the roof. The hardest part is locating the puncture point that causes membrane roof leaks. This is because before the water starts leaking into the building, it first penetrates the insulation layers, and then it spreads over the trapezoidal sheet folds. Therefore, it is not surprising that the outlet for such a leak may sometimes be several meters further away than the actual damage to the roofing.


Have you ever wondered how much water wool can absorb? How long after the removal of the leak cause does it take for the accumulated water to fully evaporate? There have been cases of building disasters as a result of roof overloading after the insulation layers have become saturated. It is also fair to point out that no designer considers a load combination that takes into account the weight of water-soaked insulation in their calculations.

The best way to avoid the serious effects of leakage is to quickly rid the insulation layers of moisture. This affects both the insulation properties and the heating or cooling expenses of the building. Experienced roofing contractors install special vents in such cases. These are so-called “mushroom vents”, which evacuate moisture more quickly and are removed before winter.


There are also active systems that notify the Property Manager of increased loads on the roof even before an actual roof leak occurs. Roof structure monitoring systems ensure the safety of the structure and help to identify where the leak is. One such solution is the Sense S-One sensors from Sense Monitoring. Such a system checks the current roof deflection every 3 minutes with an accuracy of 1 mm. In this way, it effectively contributes to the early detection of increased weight of the roof from water.

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Artiom Komardin, CSO
inżynier budownictwa z pełnym zakresem uprawnień. Absolwent Politechniki Krakowskiej oraz UJF Grenoble. Ekspert w zakresie budynków wielkopowierzchniowych, autor kilkudziesięciu ekspertyz i opinii konstruktorskich. Współzałożyciel oraz wiceprezes firmy Sense Monitoring sp. z o.o. dostarczającej platformę Inteligentny Dach do zarządzania ryzykami dachów płaskich.