# life expectancy used in 4-point inspection

**URL:** <https://forum.nachi.org/t/life-expectancy-used-in-4-point-inspection/43815>\
**Category:** AskNACHI.org Questions\
**Created:** [November 10, 2009, 7:59pm UTC](https://forum.nachi.org/t/life-expectancy-used-in-4-point-inspection/43815 "2009-11-10T19:59:57Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![system](https://global.discourse-cdn.com/internachi/original/3X/d/f/df7ced6a9ca05e7c93fa949dfc12a8c10d06c887.png) [@system](https://forum.nachi.org/u/system)\
**Post date:** [November 10, 2009, 7:59pm UTC](https://forum.nachi.org/t/life-expectancy-used-in-4-point-inspection/43815/1 "2009-11-10T19:59:57Z")

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Why in a 4-point inspection is 15 years used for the life expectancy of a a shingle roof, when I have 25 year shingles. Please call me 941-924-7036

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**Author:** ![wsiegel](https://avatars.discourse-cdn.com/v4/letter/w/3d9bf3/32.png) [@wsiegel](https://forum.nachi.org/u/wsiegel)\
**Post date:** [November 12, 2009, 10:57pm UTC](https://forum.nachi.org/t/life-expectancy-used-in-4-point-inspection/43815/2 "2009-11-12T22:57:00Z")

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Shingles are like tires. They never get their expected life, especially down here in Florida due to the intense heat. Other factors also play into when a roof will need to be replaced, not just the life expectancy of the shingles.

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**Author:** ![gbell](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/gbell/32/60114_2.png) [@gbell](https://forum.nachi.org/u/gbell)\
**Post date:** [November 12, 2009, 11:39pm UTC](https://forum.nachi.org/t/life-expectancy-used-in-4-point-inspection/43815/3 "2009-11-12T23:39:12Z")

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Because the normal life for a 3 tab shingle is 12-15 years. Shingles never last as long as the manufacturer states in Florida.

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**Author:** ![rchorey](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/rchorey/32/981_2.png) [@rchorey](https://forum.nachi.org/u/rchorey)\
**Post date:** [November 13, 2009, 2:43pm UTC](https://forum.nachi.org/t/life-expectancy-used-in-4-point-inspection/43815/4 "2009-11-13T14:43:31Z")

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The following factors affect the lifespan of roof-covering materials

- Roofing material quality: Better quality materials generally last longer.
- Installation method: Improper installation may reduce lifespan.
- Number of layers: Roofs installed over existing roofs will have reduced lifespan.
- Structure orientation: South-facing roofs will have shorter lifespans.
- Degree of roof slope: Flatter roofs will have shorter lifespans.
- Climate zone (snow & rain): Harsh climates shorten roof lifespans.
- Temperature swings: climates with large daily temperature differentials (within 24-hour cycles) will shorten roof lifespans.
- Homesite conditions (overhanging tree branches, wind, etc.)
- Roof color: Darker roofs absorb more heat which shortens roof lifespan.
- Elevation: Homes at higher elevations are exposed to more ultra violet (UV) light, which shortens roof lifespan.
- Home orientation: Roofs which receive more sun deteriorate more quickly than roofs which receive less sun.
- Roof structure ventilation: Poor ventilation shortens roof lifespans.
- Quality of maintenance: Poor maintenance will reduce lifespan.