Roofing Performance Factors
There are a variety of factors that impact a roof’s performance. The life of a roofing system varies from its initial design and construction to the environment it faces and maintenance received.
Roofing Systems are comprised of many materials that when properly constructed add value and protection for your home. The common materials needed include: sheathing/decking; flashing; underlayment; ice and water protective barriers; ridge vents; ridge shingles, and other venting.
Effects on Roof’s Performance (Incorporate the photos currently in use and add new images for new points)
Lack of maintenance: Often the greatest cause of premature roof problems is not finding and correcting minor roof issues in the early stages, especially for relatively low-sloped roofs.
Improper design: Inadequate roof slope, sagging, structures that excessively draw away under the load, inadequate draining and provision for expansion and contraction in decking material contribute to the roofing membrane weakening and splitting. Design deficiencies often can be corrected when identified with a roof replacement.
Hail: The impact of hail can loosen, fracture or remove granules from your asphalt shingles. The granules protect the asphalt matting of your shingles from sunlight and ultra violet light (U.V.). The asphalt will deteriorate very quickly once exposed to the sun. This is the reason a hail-damaged roof will prematurely fail. Hail-damaged roofs may or may not be detected by the inexperienced observer. The results of a hailstorm will void the shingles manufacturer’s warranty, as they cannot warranty against “Acts of God” such as hailstorms.
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. Wind damage creates a partial vacuum from wind blowing over the edge of the roof. The low-pressure area tries to neutralize itself by bringing in air from a higher pressure area, typically from inside the building. Air pushing up on the bottom of the roof will loosen fasteners and break the roofing adhesion over time, which makes the roof susceptible to damage in the future. Quality roofing construction counteracts the effects of wind-uplift forces.
Snow and ice: Melting snow often refreezes at a roof’s overhang where the surface is cooler, forming an ice dam. This blocks proper drainage into the gutter. Water backs up under the shingles (or other roofing materials) and seeps into the interior. During the early melt stages, gutters and downspouts can be the first to fill with ice and may be damaged beyond repair.
Condensation: Condensation can result from the build-up 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.
Moss and 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 also can work their way into a wood deck and structure. Algae also grow 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 and 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, a roof structure and home or building interior are vulnerable to water damage and rot. The problem is likely to spread, as well as allowing nearby shingles to rip easily and/or blow 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 easily are 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.
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.
Asphalt shingle construction: When asphalt shingles have been exposed to a hailstorm severe enough to dislodge granules from the surface of the shingles (in spots large enough to expose the asphalt), the roof has been compromised. The colored granules which are placed on the surface of the shingle provide an aesthetically pleasing product and protect the underlying asphalt from exposure to the sun. Prolonged exposure to sun causes asphalt to deteriorate. This is why hail-damaged roof will tend to fail prematurely.
Heavy hail damage is obvious because of the indentations in the shingle. When the surface damage of the shingle is not visible, look for indentations on vents, ridge vents, siding, or any other softer metal objects that may show impact. The effects on the shingle may not be apparent for about a year. At this time, circular areas of granules will fall off the shingle. This is often called spalling. What has occurred is that the impact of the hailstone has broken or weakened the bond between the granules and the asphalt. After a year or so of weathering, the granules fall off the shingle in the circular area of impact. With granules missing, the sunlight (UV) quickly attacks the asphalt and the maximum performance of the shingle has been compromised. The results of a hailstorm will void the shingles manufacturer’s warrant, as they cannot warranty against “Acts of God” such as hailstorms.