1. The IBHS Impact Resistance Test Protocol has only been tested on asphalt shingles at this time
  2. Product sampling:

a.  Available through the public distribution network

b.  Any products that are damaged through distribution are discarded and not used for testing

c.  Any products for which the amount of time between date of manufacture and test completion was beyond 24 months were discarded and retested

d.  For the first roll-out of results, products were sampled from those that were available in public distribution as of the time the order was placed (April 2018). Anything not available in distribution at that time was not considered

  1. Tests were conducted for new, unaged products—results may not represent performance after real-world exposure to the elements
  2. Results are representative of one batch of products from a specific plant


  1. Hail characteristics assumptions:

a.  Characteristics of real hailstones vary storm-to-storm, and even stone-to-stone

b.  Manufactured hail used in the IBHS Impact Resistance Test Protocol represent a range of characteristics of real hailstones measured through the IBHS Hail Field Study, resulting in the best state-of-the-art science. Results have been published in Heymsfield et al. 2014; Giammanco et al. 2015; Giammanco et al. 2017.

c.  Testing is conducted using spherical manufactured hail (not irregular shapes) to ensure test consistency

  1. Impact mode is visually assessed by expert judgement

Performance Evaluation

  1. Requires the use of an image processing tool (IBHS-Nemesis Impact Damage Evaluation Tool) in combination with expert judgement to assess damage
  2. Evaluation is quantitatively-based resulting in a performance score based on the average performance of all impacts for the subject asphalt shingle
  3. Evaluation is not a pass/fail criteria

a.  Allows for performance differentiation between large, very severe damage and that which is small

b.  Takes granule loss into account (a primary real-world damage mode)