Roofing Materials & the Causes of Deterioration

Rain

• Rain itself causes little deterioration in most roofing materials, but when it gets between the shingles and the roof decking, the moisture becomes trapped and leads to rot. Asphalt, metal and stone shingles won't rot, but the decking and rafters below them will. However, wooden shakes or shingles become rotted if rain accumulates between the underlayment and the shingles. Rot and moisture damage also occurs on wooden roofing materials if they aren't properly sealed or if the seal wears off.

Weathering

• Weathering refers to the various elements that wear on your roof on a daily basis, including wind, hail, ice and other natural occurrences. Some areas experience more deterioration from winter weathering, while other areas have the possibility for damage from salt spray from the sea. Metal and stone tend to hold up against weathering while wood and other organic materials deteriorate faster, according to Roof Help. Air pollutants such as car exhaust and industrial fumes also contribute to weathering.

Sun Exposure

• No matter where your home is located, your roof receives sun exposure most days of the year. UV radiation leaches the color from asphalt and wood shingles over the years and leads to brittle, cracked roofing materials. Metal, slate and high-quality clay tiles hold up the best against sun deterioration, states the Roof Shingles Help website. While metal rusts, tile and slate only take damage from sliding ice or falling tree limbs and other forms of blunt force.

Improper Design

• While other forms of deterioration that lead to roof failure remain inevitable, improper design is preventable. Roofs with improperly installed flashing, materials that are too heavy for the supports and the wrong areas of slope will all deteriorate faster than roofs with the right design, says Roof Help. Inorganic materials last longer on a poorly designed roof, but the rafters and decking below them will degrade just as quickly. Asphalt and wood shingles remain attractive and functional much longer if installed properly.