What is the average lifespan of a regular (3-tab) shingle roof?
Saturday, August 25, 2018
The expected lifespan of a 3-tab asphalt shingle roof, often called a 20-year shingle roof, is 15 to 18 years in Florida. Why does a roof shingle with a 20-year manufacturer’s warranty typically last less than 20 years? Because the warranty is against “manufacturer’s defects” during the period of the warranty, not for the actual life of the roofing components used, of which the shingles are just one component. Poor workmanship by the roofing contractor is often determined to be the cause of early failure of a roof if a claim is made against a roofing material manufacturer.
The 15 to 18 year average lifespan estimate is based on “average” conditions. Many factors contribute to a longer or shorter life of the roof; so a particular shingle roof’s life can vary—sometimes significantly—from the average. Here’s a list of conditions that affect roof longevity:
• Color of roof - A dark roof absorbs more heat, which shortens the lifespan.
- Angle of roof slope - Higher pitch roofs tend to last longer.
- Orientation of roof surface - A roof slope facing south will get more sunlight, and have a shorter life.
- Multiple-layer roof - A roof installed over an existing roof will have a shorter life. Two layers of shingle roof are allowed by building codes, so it is possible to put a new shingle roof over an existing one—just once. While a homeowner saves the tear-off labor and dump fees for removal of the old roof, the shorter life of the new roof and double expense of the tear-off and dump fees when its time for a roof again make it a poor long-term choice.
- Quality of roof material - “Economy” roof materials have a shorter life.
- Installation - Sloppy or improper installation shortens roof life. Manufacturers typically blame the roofing contractor for a roof that has a short life, and they are sometimes correct. Exposed fasteners, over-driven fasteners, and poor or missing flashing at valleys and edges will shorten the roof life.
- Attic ventilation - An unventilated or poorly ventilated attic reduces roof lifespan.
- Radiant Barrier - The foil sheet glued to the underside of roof sheathing to reflect the heat of the sun back out into the atmosphere—reducing the attic temperature in the summer—tends to also reduce shingle life because it makes the roof shingles hotter.
- Trees near roof - Tree branches rubbing on a roof or the acidity from the accumulation of leaf debris on a roof shortens its life.
- Harsh climate - Severe weather, both harsh winters and hot summers, along with big temperature swings within a 24-hour period, also shorten lifespan because of the expansion and contraction of roof materials.
Go to our blog post What is the average lifespan of the parts of a house? for rating of other house components. To understand the basis, potential use, and limitations of lifespan ratings, see our blog post ”How accurate are the average life expectancy ratings of home components? Are they actually useful?”
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To learn more about roofs and attics, see these other blog posts:
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