Haag’s Test Square Method

As we commemorate Haag’s 100th anniversary, we reflect on a century of remarkable and pivotal projects that have defined the legacy of Haag.

One such enduring contribution is Haag’s Test Square Method, a methodology pioneered by Haag engineers since the early 1960s. This method stands as a testament to simplicity, precision, and repeatability in assessing the extent of hail damage on roofs. Its significance lies in the establishment of clear rules and procedures for hail damage assessment, helping to eliminate disagreements among professionals in the field.

The Test Square method has evolved into the standard inspection procedure for determining hail damage worldwide, used by contractors, adjusters, engineers, and various stakeholders, attesting to its universal applicability.

The genesis of this methodology dates back to the 1960s, when assessing hail damage on cedar shingle roofing was a common challenge. With cedar shingle roofs boasting 350-400 individual shingles per square (100 square feet), a comprehensive assessment was a time-consuming task. In response, visionaries such as Wayne Parish, John Stewart, Stoney Kirkpatrick, and others at Haag Engineering deliberated on employing statistical sampling for hail damage assessment.

After experimenting with different sample area sizes, they found that 100 square feet or one roofing square struck the perfect balance—being statistically representative, practical in terms of time, and easily comprehensible in discussions. Recognizing the directional impact of wind-driven hail, a decision was made to conduct a test square on each directional face of the roof.

The methodology made its formal debut in “Hail Damage to Red Cedar Shingles” (American Insurance Association, 1975) and later in Haag’s publication “Hail Damage to Wood Shingle and Shake Roofs: Assessment Criteria” (Haag Engineering Co., 1985). Subsequently, it underwent peer review and was presented as a comprehensive procedure two decades ago at the North American Conference on Roofing Technology in a paper titled “Protocol for Assessment of Hail-Damaged Roofing” (Tim Marshall and Richard Herzog, 1999). Today, the Haag Test Square Method endures as a cornerstone in the realm of hail damage assessment, embodying a legacy that spans decades and continents.