5 Common Reasons a Commercial Roof Leaks


Owning and maintaining a commercial roof is a big responsibility. It can be frustrating and stressful when it springs a leak and you have no idea why or how it happened. Fortunately, it’s usually due to one of these five reasons. Knowing the source of your leaky roof is the first step in getting it repaired.


1. Poor Design

Many flat commercial roofs are poorly designed and create areas of standing water. Puddled water can cause an unnecessary amount of weight to sit on your roof. One foot of ponding water weighs about 5 pounds per square inch of surface area.

When you consider how large your commercial roof is, it’s no surprise that puddled water can put a substantial amount of stress on your building. This added pressure can damage your roof, causing it to leak. For information on how to maintain your flat roof and prevent leaking, read our article "Tips for Maintaining a Flat Roof."


2. Insufficient Drainage

Similar to a poor design, insufficient drainage can cause water to pool on your roof, resulting in the same consequence as above. As a liquid, water can and will find any cracks or crevices your roof may have. To prevent this from happening, be sure that your roof’s drains, gutters, and downspouts are all clear and working properly.


3. Material Damage

There are two crucial elements to your flat, commercial roof: the membrane, which acts as the cover of your roof, and the flashing, which seals the perimeter of your roof.


Membrane Damage

Over time, your roof’s membrane may crack, split, or shrink. These changes in the integrity of the membrane can cause it to leak. The membrane may also be damaged from fallen trees or hail. The membrane is an integral part of your commercial roof, so it is important to inspect it frequently and repair any damage you find.


Flashing Damage

Flashing acts as the protector of the membrane’s edges. It is very common for flashing to expand and contract with changes in temperature, which can cause gapping and leakage. Flashing can also become loose during storms, inhibiting its ability to prevent water seepage. Repairing the flashing on your roof can help prevent a leak from forming.


4. Improper Sealing

Various outlets on your roof can be sources of leaking and so must be properly sealed. Possible points of water infiltration in your roof’s membrane include, but are not limited to

  • Pipes
  • Drains
  • HVAC units
  • Vents
  • Hot stacks
  • Gas lines

Each of these holes in the membrane must be sealed and monitored to prevent your roof from leaking. If these outlets have not been properly sealed, it is likely that they are the source of the problem.


5. Old Age

Like many aspects of a building, your roof will have to be replaced at some point. Flat roofs typically last approximately 15–20 years before they deteriorate to a point beyond repair.


If you need commercial roofing services in the Ames, Des Moines, or Huxley areas, contact Hedrick Construction. From maintenance to new installation, we offer the services you need to stay safe and dry. We’ve been a leading roofer in Central Iowa for more than a decade. Book your appointment today!