Why Roofs Wear Out

Why Do Roofs Wear Out?


It is not a mystery as to why roofs wear out. There are four main reasons.


1. Ultraviolet Radiation (UV Rays)

2. Heat

3. Expansion & Contraction

4. Maintenance Neglect


1. Ultra Violet Radiation

As soon as a roof is installed the sun begins to deteriorate the material. Every single day (even cool and cloudy days) the UV rays from the sun damage and break down the roof. Under the exposure of UV rays of the sun, free molecules of oxygen mix with heated hydrocarbons in asphalt and deterioration begins.


Molecular breakdown by the sun dries out the oils in the roof. The roofing material becomes dry and brittle. Eventually it looses its waterproofing qualities.



2. Heat

Heat accelerates the breakdown process. The damage done from the UV rays is greatly speeded up when the weather is hot. A typical capsheet roof gets up to 160º on a hot summer day when the air temperature is 90º. Over time the roof looses flexibility and becomes weak.



3. Expansion & Contraction (thermal shock)

The roof expands and contracts every day. This is referred to as thermal shock. The sun’s heat makes the roof stretch out in the day. At night, the evening cools the roof causing it to contract. Flashings and drains are typically metal. They expand and cool much quicker than the roof membrane. Over time, the tremendous strain from the thermal shock causes metal drains and flashings to pull away from the roof assembly at these critical areas. The movement also causes the roof to split.



4. Maintenance Neglect

When a roof is not maintained properly, great damage will occur causing the life span of the roof to be reduced.


Debris clogs up drains; ponding water wears out low areas and weakens the roofing membrane. Chemicals attack the roof from the various sources; air-conditioning units, swamp coolers and roof top equipment.


Heavy foot traffic to maintain roof top equipment, grease, improperly installed equipment all damage the roof. Neglect can hastily speed up the process for roof failure.


Cracks in this asphalt show how the ultra violet radiation breaks down the hydrocarbon molecules that most roofs are made of.

This is fiberglass capsheet roofing material.  The hot sun and ultra violet light accelerate roof deterioration.

Ponding areas along the edge of this roof have increased the speed of the breakdown process.

Ultraviolet light and the hot California sun have literally baked the life out of this roof.

The tremendous strain on a roof is evident in this photo. In the foreground we see the roof buckling. Near the skylight the roof is pulling away.

This 5-year old roof shows extreme damage from the leaking cooling tower.

Debris like this can damage the roof.

This drain is in poor condition. This will cause premature roof failure. Leaks in a drain area cause major damage.

Century Roofing 3 Generations

8218 Ensign Avenue

Sun Valley, CA, 91352

License # 958049


Local # (818) 896-4351

Toll-Free # (800) 244-8286


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