Raise The Roof!
The life expectancy of your asphalt shingled roof depends on factors that include roof design and the climate you live in, as well as the quality of installation and long-term care and maintenance.The expected life of a roof covering depends on many variables including:
Asphalt Shingle Quality: Type, quality, thickness, shingle design and rating of roofing material selected.
Asphalt Shingle Colour: Lighter colours tend to resist sunlight damage and last longer.
Roof Shingle Age: Typical life expectancy for roofing products can vary widely as a function of the material composition, type, installation details, and other factors.
Roof Slope: Conventional roof shingles should not be used on slopes less than 3 in 12 – that is 3″ of rise in 12″ of run. If shingles must be applied on such a low slope, say for aesthetic reasons, they’re installed as a cosmetic applause on top of a nailable waterproof membrane, or laminated with courses of sealing membrane between every shingle course (costly and still risky).
Roof Problem Areas: Complex roof shapes that make under-roof venting difficult or unfortunate architecture that places obstructions such as a wall or a chimney right in a roof valley, or causes other shapes which interfere with good roof drainage can affect shingle life expectancy (shingles depend on slope and drainage to avoid roof leaks).
Sun Exposure: Orientation towards sunlight can cause faster wear on those slopes than on shaded roof slopes.
Roof Ventilation: Un-vented roofs stay at a higher surface temperature and can be expected to have a shorter life.
Technical Material Composition and asphalt shingle design details (roofing material components, manufacturing process, wind-uplift prevention).
Manufacturing Defects and Asphalt Shingles: Even the best manufacturers are at risk of producing a defective product. The asphalt shingle manufacturing line is a challenging environment where variations in the process can produce a defective product with a reduced life.
Mechanical-damage to Roof Shingles: Mechanical damage to asphalt roofing results in granule loss, cuts, chips, pits, tears and can result from wind to falling tree limbs and everything in between. Mechanical damage to shingles may require only spot repairs or it may be so extensive as to require complete roof replacement.
Weather and Weather Exposure: Variations in climate and other local weather conditions affect roof shingle life. Higher thermal load (hotter climates) means shorter life.
Nailing of Asphalt Shingles: Asphalt shingle roof nailing errors include improper nailing pattern, omitted nails and too many nails. The older roof nailing guns that used staples required even more careful use of that tool.
Underlayment Effects on Shingle Life: Omitting roofing underlayment (roofing felt or “tar paper” installed before shingles are applied), installing underlayment or shingles over a wet, icy, or snow-covered roof deck can reduce shingle lifespan.
Roof Flashing Errors: Uneducated flashing installers may misplace flashing, omit flashing, use improper flashing, nail through flashing, rely on roof cement rather than flashing, and/or misplace the drip edge with its vertical section behind rather than over gutters. And remember, shingles depend on slope and drainage to avoid roof leaks.
Courtesy: Homeservice Club of Canada