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Guide to Causes of Thermal Splitting or Cracking Asphalt Roof Shingles
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• Causes & photographs of asphalt roof shingle cracking failures
• How to make a shingle warranty claim
• Links to Articles on other types & photographs of organic felt asphalt roof shingle failures
• Links to Articles on Asphalt roof shingle blisters and splices, photographs

This document tells readers how to identify & explain asphalt shingle cracking or thermal splitting, what causes shingle cracks or splits, and how to distinguish this product failure (which may be entitled to a warranty or class action claim) from other roofing product failures or defects.

Readers are also invited contribute roof failure information to the web author for research purposes. web author for research purposes. © Copyright 2009 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

What does it look like?
We have observed a variety of torn or split shingles:

• Horizontal or vertical tears across multiple 3-tab shingles
• Horizontal, vertical, and diagonal tears across multiple strip-type shingles
• Horizontal, vertical, diagonal, and corner tears across multiple laminate-type shingles
• Both horizontal and diagonal or vertical tearing may occur in the same roof

What is the Cause of Cracks in Fiberglass-based Asphalt Roof Shingles?

• It's possible that shingles made by some manufacturers do not meet the ASTM Standards for tear resistance.
  
  
• Even where shingles meet the Standards, it's possible that the standards themselves were defective. In particular, for a time the asphalt roof shingle standards combined these concerns:
  • A thin fiberglass mat was permitted as the shingle substrate, lacking adequate tear resistance
  • The wind uplift prevention bonding adhesive was too strong, causing the shingles to bond into nearly a single continuous surface that lacked adequate movement to respond to significant changes in temperature without tearing the bound surface
    
    
• In any case, Fiberglass mat may lack adequate tear resistance
  
  
• Self-sealing tabs on shingle backs may glue shingles together with too much strength, causing the roof covering to form a single large membrane which cannot accommodate large temperature changes. This explanation was discovered across the asphalt shingle industry.
  
  
• Reduced total amount of asphalt in thin fiberglass mats might become brittle after exposure to heat and sunlight
  
  
• Temperature swings probably contribute to the onset and extent of tearing, and we'd expect worse tearing where temperature swings are more extreme such as in Northern climates.
  
  
• Nailing or placement pattern of shingles: "laddering" vs. "staggered." On laminate and strip type shingles we have inspected roofs on which damage is found occurring at the corners of shingles rather than in the middle of the shingle material. It appears that as temperatures dropped and the glued-together-roof-membrane cools and contracts, the natural point at which movement occurs is where shingles are end-butted together.
  
  When the pattern of end-butts is laddered rather than staggered up the roof we have found corners tearing off of shingles following the laddering pattern exactly. (Laddering is not a recommended installation pattern according to NRCA and ARMA publications nor according to instructions from some manufacturers.)
  
  Laddering alone cannot be blamed for this failure however, as we have seen similar shingle tearing following a staggered end-butt pattern up other roofs. However laddering may indeed create a more localized natural point of separation on a roof, causing most of the movement to occur in a smaller area when the roof material contracts with cooling.

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Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

ASPHALT ROOF SHINGLES
  SHINGLE LIFE / WEAR FACTORS
  ASPHALT SHINGLE FAILURE TYPES
  ALGAE, FUNGUS, LICHENS, MOSS on SHINGLES
  BLACK STAIN REMOVAL & PREVENTION
  BLISTERS on ASPHALT SHINGLES
  CRACKS in FIBERGLASS SHINGLES
  CUPPING ASPHALT SHINGLES
  CURLING ASPHALT SHINGLES
  FISHMOUTHING ASPHALT SHINGLES
  GRANULE LOSS from SHINGLES
  HAIL DAMAGED SHINGLES
  LADDERING & STAIR STEPPING SHINGLES
  MOSS & LICHENS on SHINGLES
  ORGANIC FELT SHINGLE DEFECTS
  SPLICE DEFECTS on ASPHALT SHINGLES
  STAINS on ROOF SHINGLES
  WHAT ARE ASPHALT SHINGLES

• Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. (727) 595-4211 mark@BestTampaInspector.com
• Hankey and Brown home inspectors, Eden Prairie, MN, technical review by Roger Hankey, prior chairman, Standards Committee, American Society of Home Inspectors - ASHI. 952 829-0044 - hankeyandbrown.com
• Arlene Puentes, a licensed home inspector, educator, and building failures researcher in Kingston, NY.

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