Functional damage:
1.  Shortens expected service life
2.  Reduces ability of roof to shed water

"Functional Damage" is an important term to insurance companies and shingle manufacturers.  Take this definition into account when evaluating roofs.

Use the following links to better understand what you see on a roof:

  1. Asphalt Shingle Inspection Concerns;
  2. 2021 IRC R905.2 Asphalt Shingles;
  3. Mastering Roof Inspections ; (Asphalt Shingles (#55-#109)
  4. Asphalt Shingle Inspection Field Guide, $18.99, by Kenton Shepard
  5. Inspecting Shingle Bonding;
  6. Craze-cracking;
  7. Identifying Wind Damage;
  8. Batch Problems;
  9. Blisters VS Hail Damage;
  10. Biological Growth;
  11. Uniform Granule Loss;
  12. Racking of Shingles(GAF Technical Advisory Bulletin)
  13. Buckling of Shingles
  14. About Shingle Warranties
  15. Factors Affecting Shingle Aging
  16. White/Brown Stains below Roof Vents;
  17. The History of Asphalt Shingles(CASMA)
  18. Asphalt Shingle Sealant Strips(Donan Engineering)
  19. Impact Resistance of Asphalt Shingles  (Insurance Institute for Business and Home Safety)
  20. 66 GAF Technical Bulletins
  21. Telescoping Ladder Maintenance
  22. FM Global: Roof Inspection Resources
  23. Asphalt Roofing Manufacturer's Association
  24. InterNACHI Asphalt Shingle Inspection online video course(3.25 hrs, InterNACHI members only)
  25. Building Codes At this page, for general IRC information, choose ICC, for jurisdictional (state and city) building codes, choose UP Codes. go to Chapter 9, Roof Assemblies.