The intent of this article is to provide an overview of the content of the Guidelines and the resources contained within. Adjusters can utilize this information to more effectively evaluate damage claims in a post-earthquake environment.

Myths Debunked

Several myths regarding earthquake damage assessment and repairs developed during the Northridge earthquake response. These myths were associated with the most significant areas of post-Northridge technical controversy for residential wood frame buildings: “hidden” damage to structural framing, foundation damage, and appropriate repairs to restore structural integrity to wall finishes and concrete foundation elements (see sidebar, Myth Versus Reality).

The widely divergent opinions offered by the engineering community regarding the extent of damage and appropriate repairs for these areas resulted in wide disparity and inconsistency in payment of earthquake claims for similar levels of damage, prolonged disputes and costly litigation. Research and testing performed in the development of the Guidelines provided the scientific and engineering data to debunk these myths. The research findings have been incorporated into the investigative and repair portions of the Guidelines.

Guidelines Content

The Guidelines cover all aspects of earthquake damage assessment and repair for residential wood frame buildings, including guidance on damage patterns and inspection procedures. The chapters of the Guidelines and a brief comment on the content follows:

• Section 1: Introduction: Overview of earthquakes and the various types of damage they cause and general aspects of damage assessment, including a description of the states of an assessment and inspection checklists.
• Section 2: Earthquake Ground Motions and Damage Potential: Various quantitative and qualitative measures of earthquake ground-shaking, and the general types of damage associated with various levels of ground-shaking.

Sections 3 through 8 address the primary components of wood frame buildings and describe common types of constructions/systems, typical non-earthquake-related conditions, and typical types of earthquake-related damage. Guidelines are provided for conducting an inspection, appropriate repair of common types of nonstructural earthquake damage, and the circumstances indicating the need for technical consultant assistance.

• Section 3: Geotechnical Aspects
• Section 4: Foundations and Slabs-on-Grade
• Section 5: Wall Elements
• Section 6: Floors, Ceilings, and Roofs
• Section 7: Fireplaces and Chimneys
• Section 8: Mechanical, Electrical, and Plumbing Systems
• Section 9: Working with Technical Consultants
• Section 10: Glossary and Acronyms

The Guidelines are comprehensive and can be quite daunting. However, at the start of each section, the pertinent information necessary for performing an earthquake damage assessment has been summarized into two sections: the Quick Guide and Summary. The Quick Guide provides a summary of what to look for, where to look, when to call a technical consultant, and repair guidelines. The Summary provides an overview of the salient information in the section, including non-earthquake damage mechanisms and distinguishing between earthquake and non-earthquake-related damage.

Earthquake Damage Assessment

The keys to competent, consistent earthquake damage assessments are as follows: conducting a thorough site inspection and systematically documenting site observations; using the services of a technical consultant as appropriate; distinguishing between earthquake-related damage and unrelated conditions; and recommending appropriate repair of earthquake damage once it is identified.

Having a basic knowledge of the level of damage to expect given the intensity of shaking at a site and understanding how earthquake ground motions affect residential wood frame structures before performing an assessment will allow an adjuster to make better observations. Section 2 of the Guidelines provides background and resources for the measures of ground-shaking intensity that are readily accessible online within minutes following a California earthquake, and the relationship between the intensity of ground-shaking, building vulnerabilities, and the potential for damage.

Site Inspection and Assessment

Performing a thorough, competent site inspection requires knowing what to look for, where to look, and systematically inspecting the property for signs of potential earthquake-related distress. The site investigation should be performed in stages — from the general to more detailed — only when indications of earthquake damage or potential damage are found. Visual assessment by a trained insurance claim representative or general contractor utilizing the information contained within the Guidelines as a road map should be the default. Further detailed assessment by an engineering consultant should follow only as needed.

At the onset of the site inspection, the owner/occupant should be interviewed to obtain pertinent information regarding the condition of the property prior to the earthquake, experiences during the earthquake, disruption of and damage to contents, and observations regarding cracks, potential damage, or unusual conditions observed at the property. The Guidelines provide a sample questionnaire to document the building occupants observations. The information provided will identify areas to focus on during the site visit, allow for evaluation of the intensity of shaking at the site and allow determination if claimed damage is consistent with the intensity of shaking at the site.

During the initial assessment, systematic visual examination of the various components of residential construction should be performed as indicated in the Guidelines assessment and methodology sections. To facilitate the site inspection process, the Guidelines provide a General Earthquake Damage Inspection Checklist (checklist) to document site observations. The checklist incorporates the pertinent aspects of what to look for and where to look from Sections 3 through 8 of the Guidelines. Completion of the checklist during the site visit, supplemented with photo documentation of observed conditions, will ensure the key and most vulnerable components of the structure were observed, documented, and evaluated for signs of possible earthquake-related damage.

Two optional checklists, Crawlspace Inspection and Attic Inspection, are provided in the Guidelines to facilitate the site inspection. Earthquake-induced damage in attics or crawlspaces, in the absence of conspicuous visible damage sufficient to trigger the need for an engineering assessment, is extremely unlikely. Given the hazards associated with entry into these spaces, such an inspection should be performed by an individual qualified by training and experience.

Technical Consultants

Contrary to popular belief and practice after the Northridge earthquake, the services of an engineer are generally not required for post-earthquake assessment of single-family, wood frame houses. Exceptions include:

• Earthquake damage compromising the safety of the building identified.
• Buildings with damage indicating possible structural damage or instability in the ground beneath or adjacent to the building.
• Buildings with construction or configuration known to be vulnerable to earthquakes.

Sections 3 through 8 of the Guidelines contain sub-sections that identify specific observations that would indicate the need to retain an engineer for further evaluation. Many of the conditions that trigger the retention of engineering services have been incorporated as questions into the checklist to facilitate this assessment process.

Earthquake vs.Non-Earthquake

Post-earthquake damage assessments often must distinguish between pre-existing damage and damage caused by the earthquake. Following an earthquake, building owners and occupants have a heightened awareness of their buildings. Many pre-existing conditions are first noticed following an earthquake and are assumed to be caused by the event. In addition, many conditions that are consistent with the normal, expected performance of a structure are mistakenly assumed to be caused by the event.

Thus, it is important that the adjuster has access to information that will allow him to distinguish between earthquake and non-earthquake-related damage. Sections 3 through 8 of the Guidelines each contain a sub-section that discusses the normal, expected performance of the component as well as non-earthquake-related damage mechanisms. This information will provide guidance for the adjuster when making this assessment.

Once earthquake damage has been identified, it is necessary to determine the appropriate repair to restore the structural integrity of the damaged component to its pre-earthquake condition. While repair of significant structural damage will require engineering design, repair recommendations for nominal earthquake damage to wall surfaces (a vast majority of claims) and other components may be addressed utilizing the repair tables provided in Sections 3 through 8. These tables provide a selection of appropriate repairs for damage that can be reliably identified and appropriately repaired by qualified tradesmen without the assistance of a technical consultant.

Working with Technical Consultants

Effective engineering involvement in earthquake damage assessments and repair requires effective communication between the engineer and adjuster to ensure there is common understanding of the questions to be addressed to adequately adjust the loss and other parameters of the engagement (inspection and reporting guidelines, professional fee expectations, and so on). Section 9 of the Guidelines provides guidance on working with technical consultants and includes a suggested outline for a comprehensive earthquake damage assessment that can be tailored to specific needs and circumstances.

The occurrence of the next earthquake catastrophe is a certainty — something made readily clear in recent months. Only the date and location are unknown. Now is the time to acquire the knowledge necessary to respond effectively to the challenge of earthquake damage assessment. Download and read the Guidelines, then pack it with your catastrophe response gear.

Lisa Shusto, P.E. is a senior managing engineer at Exponent Failure Analysis Associates, an engineering and scientific consulting firm specializing in the investigation, analysis, and prevention of failure in engineered structures and systems. She may be reached at 310-754-2701, [email protected], www.exponent.com.

John Osteraas, Ph.D., P.E. is group vice president at Exponent Failure Analysis Associates. He managed the Assessment and Repair of Earthquake Damage in Wood Frame Construction project for the Consortium of Universities for Research in Earthquake Engineering, which developed the Earthquake Damage Assessment Guidelines discussed in this article. He may be reached at 650-688-7206, [email protected].