Natural Enemies to Roofs

 

Sun, rain, wind, and cold — a roof system’s performance is affected by much of what nature throws at it. Knowing about these and other factors will help you make informed roof system buying decisions:

 

 

Sun

Heat and ultraviolet rays cause roofing materials to deteriorate over time. Deterioration can occur faster on the sides facing west or south.

 

Rain

When water gets underneath shingles, shakes, or other roofing materials, it can work its way to the roof deck and cause the roof structure to rot. Extra moisture encourages mildew and rot elsewhere in a house, including walls, ceilings, insulation, and electrical systems.

 

Wind

High winds can lift shingles’ edges (or other roofing materials) and force water and debris underneath them. Extremely high winds can cause extensive damage.

 

Thermal Shock

Thermal shock is the expansion and contraction of the roof system due to extreme temperature changes.

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Condensation

Condensation can result from the buildup of relatively warm, moisture-laden air. Moisture in a poorly ventilated attic promotes decay of wood sheathing and rafters, possibly destroying a roof structure. Sufficient attic ventilation can be achieved by installing larger or additional vents and will help alleviate problems because the attic air temperature will be closer to the outside air temperature.

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Ice Dam

An ice dam is a ridge of ice that forms at the lower edge of a roof and prevents water produced by melting snow from draining off the roof. The water that backs up behind the dam can leak into a building and cause damage to walls, ceilings, insulation, and other areas.

 

The snow on a roof surface that is above 32 degrees F will melt. As water flows down the roof, it reaches the portion of the roof that is below 32 degrees F and freezes. This creates an ice dam.

 

The dam grows as it is fed by the melting snow above it, but it will limit itself to the portions of the roof that are, on average, below 32 degrees F. So the water above backs up behind the ice dam and remains a liquid. This water finds cracks and openings in the exterior roof covering and flows into the attic space. In the most common case, the water simply backs up and flows under the shingles. From the attic, it could move into exterior walls or through the ceiling insulation and stain the ceiling finish.

 

For a roof to last, your Roofing System must include protection from ice dams and wind-driven rain. This is accomplished by installing waterproofing underlayment directly beneath the shingles.

 

In addition to protecting the roof deck from damage from ice dams and wind-driven rain, Ice and Water Shield should be used on areas of the roof where water has a tendency to collect or flow. Valleys, vents, chimneys, and skylights are examples of spots where waterproofing underlayment should be considered.

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Moss & Algae

Moss can grow on moist wood shingles and shakes. Once it grows, moss holds even more moisture to a roof system’s surface, causing rot. In addition, moss roots can also work their way into a wood deck and structure. Algae also grows in damp, shaded areas on wood or asphalt shingle roof systems. Besides creating a black-green stain, algae can retain moisture, causing rot and deterioration. Trees and bushes should be trimmed away from homes and buildings to eliminate damp, shaded areas, and gutters should be kept clean to ensure good drainage.

 

Trees & Leaves

Tree branches touching a roof will scratch and gouge roofing materials when the branches are blown by the wind. Falling branches from overhanging trees can damage or even puncture shingles and other roofing materials. Leaves on a roof system’s surface retain moisture and cause rot, and leaves in the gutters block drainage.

 

Missing or Torn Shingles

The key to a roof system’s effectiveness is complete protection. When shingles are missing or torn off, the roof structure and the home or building interior are vulnerable to water damage and rot. The problem is likely to spread; nearby shingles are also ripped easily or blown away. Missing or torn shingles should be replaced as soon as possible.

 

Shingle Deterioration

When shingles are old and worn out, they curl, split, and lose their waterproofing effectiveness. Weakened shingles are easily blown off, torn, or lifted by wind gusts. The end result is structural rot and interior damage. A deteriorated roof system only gets worse with time; it should be replaced as soon as possible.

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Flashing Deterioration

Many apparent roof leaks really are flashing leaks. Without good, tight flashings around chimneys, vents, skylights, and wall/roof junctions, water can enter a home or building and cause damage to walls, ceilings, insulation, and electrical systems. Flashings should be checked as part of a biannual roof inspection and gutter cleaning.

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Ventilation and Insulation Are Key

 One of the most critical factors in roof system durability is proper ventilation. Without it, heat and moisture build up in an attic area and combine to cause rafters and sheathing to rot, shingles to buckle, and insulation to lose its effectiveness.  Therefore, it is important to never block off sources of roof ventilation, such as louvers, ridge vents, or soffit vents, even in winter. Proper attic ventilation will help prevent structural damage caused by moisture, increase roofing material life, reduce energy consumption, and enhance the comfort level of the rooms below the attic.