Most commercial and industrial buildings feature flat roofs, as they provide plenty of space for the larger HVAC and air purification systems, as well as for the necessary vents and other roof penetrations, these industries require. Unfortunately, rooftop appliances and penetrations can also be the cause of many roofing leak issues. There are strategies to minimize this problem. 

1. Pitch Pockets

Pitch pockets are one of the most effective ways to guard against leaks around oddly shaped roof penetrations that can't be easily sealed using flashing and other common means. A metal barrier is installed around the penetration so only a small space remains between penetration and barrier. This is then filled with a hot asphalt mix that forms around the penetration and prevents leaks. 

2. Flashing and Seals

Metal flashing is used around angular appliance joints and penetrations, such as one would find around an HVAC unit or a square vent. Flashing is typically made of aluminum and it is sealed to both the roof and the appliance or penetration with a tar sealant. Rubber seals, also called boots, are similar to metal flashing but they are reserved for round and curved pipes and penetrations, as they form a tight seal on the curve.

3. Access Paths

Having access to service and maintain appliances and other penetrations can lead to roof damage, both from the foot traffic over the roofing membranes and due to dropped tools and equipment. Your roofer can install a built-up access path and service pad around penetrations and appliances. This is a sturdy area that can better withstand foot traffic. 

4. Grading and Drainage

Water sometimes pools around a penetration or appliances due to grading issues. Shuttles can be used to route runoff around larger items on the roof, diverting the flow to the nearest drain or gutter. All roofs should be slightly graded or sloped toward drains or perimeter gutters.  Additional drains may also need to be installed so that water doesn't pool around and cause leaks near penetrations. 

5. Bird Prevention

Birds often set up nests near rooftop items, as these items may produce warmth and provide shelter. However, the weight and acidity of the bird droppings can eat through the roofing material around the appliance or penetration that has become a nesting site. Caging appliances to prevent bird access and installing bird prevention devices like spikes can solve the issue. 

Contact a commercial/industrial roofing service if you are concerned about leaks around the penetrations and appliances on your flat roof.