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Invest in Your Roof


Mike KleinOne of the most important activities property managers and maintenance superintendents can perform to protect commercial and large residential facilities is a 

regular and thorough inspection of their facilities’ roofing systems. Regular, scheduled inspections and routine maintenance can be the difference between a roof that meets or exceeds its rated service life and one that fails prematurely. It will also keep you within your warranty.

But the benefits of roof inspections don’t end there. Inspection programs can also reduce the need for emergency repairs, limit damage to the building’s structure and interior, and reduce the risk of an unhealthy living environment for occupants.

In most cases, workers should inspect roofs twice each year: once in the fall and once in the spring. The fall inspection helps identify defects that might have developed during the summer, when roofing components undergo high thermal stresses and exposure to prolonged ultraviolet (UV) light. Similarly, the spring inspection identifies defects caused by ice and snow accumulation or shrinkage caused by low temperatures. Staff should perform additional inspections following heavy storms or high winds.

The details of the roof inspection program vary with the type of roof and its exposure. Roofs with high levels of foot traffic or concentrations of mechanical equipment require inspectors to look more closely for physical damage to the membrane. Built-up roofs have different inspection requirements than single-ply, metal or vegetative roofs.

Despite the differences, these common trouble spots can develop in practically any type of roof:

  • A clogged or restricted drainage system. Debris, such as leaves and construction materials, can build up in or around roof drains. Restricting the flow of water from the roof can cause ponding or allow water to back up under the roof’s protective membrane. Your staff should regularly clear all roof drains and keep the roof free of debris that could eventually make its way into drains.
  • Ponding water on the roof. Prolonged exposure to water can accelerate the breakdown of some roofing materials. The weight of the water standing on the roof can also compress the roof’s insulation, increasing the depth and width of the ponding and causing even more standing water.
  • Exhaust system damage. Inspections also should include a check of building exhaust systems, which often vent through a building’s roof and directly onto the roof surface. Depending on the interior operation the exhaust system serves, these fumes can cause significant damage to the roof membrane.

Built-up roofs consist of several layers of reinforcing materials embedded in waterproofing materials. A coating of gravel, granules, or a reflective coating protects the top surface from UV light. Common problems with these systems include:

  • Alligatoring. A series of small cracks can develop in the roof’s surface as the result of shrinkage of the asphalt material. As the problem develops, it looks like dried mud or alligator skin. Left uncorrected, the cracks will grow into splits in the membrane.
  • Blisters. These soft bubbles form in the roof’s membrane due to moisture trapped underneath. They can be as small as a dime or up to several feet across. Bubbles are most noticeable on hot days and can be easily broken by foot traffic.
  • Ridges. These result from two main causes—thermal expansion of the roofing material and separation of the underlying insulation from the roof deck. The stress in the ridge eventually becomes sufficient to tear the roofing materials.


It is important to keep a log book or computer file of photographs and notes taken with each inspection. You should also have the repairs done by a roofing contractor certified by the membrane’s manufacturer – and then photograph the finished repair. If you are not comfortable making the inspections, WPM recommends having an independent inspector from a roofing contractor.

These recommendations will help maintain your roof’s warranty and prolong its life, saving you lots of money in the long-run. Remember, an investment in your roof is money well spent.