Commercial Roofing: Common Causes of Leaks

Roof leaks range from a small drip that causes water spots on ceiling tiles to a stream of water that quickly ruins drywall and wood flooring. Most leaks start out small, but stormy weather and poor roof maintenance can make them grow fast. If your building has a roof leak, you should call a company that specializes in commercial roofing to inspect it for the following conditions:

Improperly Installed Equipment

A rooftop is a great location for satellite dishes, advertising signs, and other equipment that is located above ground level. However, some building owners install the equipment by fastening it with screws that penetrate the roof membrane. Although the seal around the screws may seem tight, water will penetrate it and waterlog the roof deck underneath. To repair the problem, the equipment is removed and the damaged section is resealed.

Expanded Screw Holes

Improper installation and weather damage cause the screw holes on panel roofs to expand around the screws that hold the panels in place. Even the smallest expansion creates a path for water to penetrate the membrane, and a large expansion causes panels to blow away. If the panels on your building have not been inspected recently, have them inspected by a company that specializes in commercial roofing as soon as possible.


Due to the city's humid subtropical climate, blistering is frequently the cause of a commercial roof leak. Commonly the result of improper installation and dry lapping, blistering worsens in hot weather. If the blisters grow large enough, they may rupture and inhibit the roof's ability to deflect water. Small blisters are seldom problematic and rarely require repair.

Loose Flashing

Flashing seals the crevice where a roof abuts to protrusions such as vents and air conditioning ducts. Over time, flashing may lose its seal and create an easy path for water to reach the deck and ceiling underneath. A telltale sign of loose flashing is water damage to the ceiling area just beneath a vent, a chimney, or another type of protrusion. The problem is usually easy to correct, but leads to serious damage if it is left unaddressed.

Improper Sloping

A roof that lacks a slope, or has several slopes, which are incongruous for draining water, develops pools of water that only disappear when they evaporate. Over time, this phenomenon – commonly referred to as "ponding" – may cause water to penetrate the membrane. Installing taper installation and covering it with a new surface is an effective method for correcting improper sloping.


The problems above commonly cause leaks, and fixing them immediately is the best way to keep them from causing expensive damage. Some leaks result from non-maintenance issues, such as improperly installed equipment or an improperly installed roof system, but most of them result from improper maintenance. If your building has a roof leak, call a company that specializes in commercial roofing, and set up a maintenance plan for preventing problems in the future.

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