Typical Causes of Roof Problems
A. Lack of Maintenance
The failure to find and correct minor roof deterioration in the earliest stages is probably the greatest cause of
premature roof problems. This is particularly true of roofing materials applied on relatively low-sloped roofs.
All roofing materials deteriorate from exposure to the weather at rates determined largely by the kind of material and
the conditions of exposure. In general, inorganic roofing materials tend to deteriorate less rapidly from exposure than
organic roofing materials. All types of roofing materials may be damaged by hail.
Exposure to air pollutants and industrial or salt-laden atmospheres may accelerate the deterioration process of some
C. Wind Damage
Roofing materials are subject to damage from strong winds and flying debris. Generally, roofs are not designed to
withstand winds of hurricane and tornado intensity. However, roofs may also be damaged by winds of moderate
intensity, with gust that may reach 50 to 75 miles per hour. The primary cause of wind damage is from the partial
vacuum created by wind blowing over the edge of the roof. Nature tries to neutralize the low-pressure area by
bringing in air from a higher pressure area, usually from inside the building.
This air pushes up on the bottom side of the roof assembly and, over time, loosens fasteners and breaks the adhesion
making the roof susceptible to damage from the next moderate or strong wind. To counteract the effects of winduplift
forces, the roofing and insulation should be adequately fastened to the roof deck, and a securely-fastened
perimeter detail should be provided.
D. Improper Design
Troublesome and costly roofing problems are often the result of faulty initial design of the roof system. Design
deficiencies are costly to correct, and usually can only be corrected during roof replacement. However, unless design
deficiencies are discovered and corrected during roof repair or re-roofing, the problems relating to them most likely
will recur. Some examples of faulty design are:
Weak roof structures that deflect excessively under load, causing splitting of the roof membrane
Inadequate roof slope, sagging roof structure, or insufficient number or location of drains, resulting in ponding water
Inadequate provision for expansion and contraction at changes in deck material or direction, causing membrane splits.
Incompatible roof materials - i.e. the use of asphalt to adhere a torch-on material (APP).
E. Flashing Failures
The function of flashings is to provide a watertight junction between roofing materials and roof projections or other
parts of the structure, and between roof sections. Flashings should be designed to furnish service for at least as long
as the materials used in the field of the roof. Flashings are the most vulnerable part of any roof. Their importance and
the importance of maintaining them properly cannot be overemphasized.
Many early roof problems are actually flashing problems. Often, repairing the flashings or providing new flashings is all
that is needed to make the roof watertight again.
Most flashing problems result from inadequate flashing design or faulty construction. Many flashing problems can be
reduced or eliminated by careful examination by competent inspectors during roof installation, and by regularly
scheduled inspection and maintenance.
In many instances, leaks occur at flashings where there are no flashing defects. These leaks may be the result of open
joints in a masonry wall or coping cap, which permits water to enter behind the flashings and into the building. This
problem may be eliminated by "through-wall" flashings.