Cause and Origin: Weather vs. Construction Damage

Authored by Rimkus Forensics Marketing Team.
Published May 13, 2026.

A major coastal storm moves through a metropolitan area, and within days, three claims arrive from adjacent commercial buildings: one with roof membrane separation, another with field shingle loss, and a third showing water intrusion at every window head. All three owners attribute the damage to the storm.

Forensic investigation may tell a different story. Post-storm field investigations may find the weather event was a precipitating cause while contributing factors can include improper fastening, inadequate flashing, or deferred maintenance: conditions that may have predated the loss by months or years. For claims managers evaluating coverage, damage attributable to wind force may fall within policy terms while damage associated with installation deficiencies or unmet maintenance obligations may not, depending on the policy language and jurisdiction.

Cause and origin investigation sits at the intersection of engineering, meteorological, and materials analysis. This article examines how investigators distinguish weather-caused damage from construction deficiencies and maintenance failures, and why that determination matters for coverage decisions, subrogation potential, and claims resolution.

Key takeaways: How cause and origin investigations separate weather damage from construction deficiencies

Accurate cause determination may affect coverage decisions, subrogation potential, and litigation defensibility in property damage claims.

What drives the investigation

Three factors commonly shape how investigators frame a cause and origin case.

• Damage pattern is often a primary investigative starting point, rather than storm severity alone: where damage occurs on a structure often reveals more than how hard the storm hit
• Forensic meteorology reconstructs site-specific conditions using Doppler radar, surface observations, and spotter reports; nearest-airport weather data alone is often insufficient for site-specific analysis 
• The 2023 amendment to FRE Rule 702 may raise the evidentiary bar for cause and origin opinions, which may place greater emphasis  on documented methodology

How investigations typically proceed

Two disciplines anchor the analytical work once a case is active.

• Field documentation is intended to preserve perishable evidence before repairs begin; burnish marks, fastener conditions, and crack face morphology may change or become less discernible over time 
• Separating a storm’s contribution from a pre-existing deficiency often requires baseline evidence: prior inspection reports, pre-storm photographs, maintenance records, and construction documents

Each element contributes to an opinion intended to withstand Daubert scrutiny. For questions about an active matter, contact Rimkus to discuss cause and origin investigation.

What is a cause and origin investigation?

The question in property damage disputes is rarely whether damage occurred; it is what caused it, when it started, and whether more than one factor contributed. ASTM E2713-25 provides a widely referenced framework for forensic investigation methodology; the American Society of Civil Engineers publishes parallel guidelines for forensic engineering practice that describe the investigation methodology courts commonly evaluate when assessing expert testimony reliability.

Concurrent causation cases involve losses where both covered and uncovered perils may have contributed. Most states focus the analysis on the dominant cause of a loss; others require separating covered damage from non-covered damage; and many insurance policies contain clauses that can alter the analysis entirely depending on how causes are defined. Courts may expect expert opinions to rest on documented methodology, in addition to professional judgment.

What are the common causes of property damage?

Property damage claims rarely present a single, unambiguous cause. Investigators typically evaluate four broad categories before forming a causation opinion.

Weather-related damage

Wind, hail, and flood events are frequently cited causes of property damage claims. High winds generate uplift forces across roof assemblies; hailstones fracture surface materials and displace protective granules; flood and storm surge introduce moisture to systems not designed for sustained water contact.

Construction and design deficiencies

Construction deficiencies are conditions present from the time of installation: improper fastening patterns, inadequate flashing details, missing or incorrectly applied sealants, and assemblies that do not meet applicable code requirements. These conditions may not produce visible damage until a weather event applies stress that the assembly may not have been properly equipped to resist.

Deferred maintenance and aging

Building materials deteriorate over time. Sealants harden and lose adhesion; roofing membranes thin and become brittle; drainage systems accumulate debris that redirects water to unintended locations. A storm that would cause no damage to a well-maintained assembly may produce significant damage to one that has been neglected.

Sudden impacts

Vehicle strikes, falling trees, and similar impact events produce damage patterns distinct from weather loading or gradual deterioration. Impact damage typically presents as localized deformation or fracture at the point of contact, with distribution that does not align with wind pressure zones or moisture pathways.

How do engineers determine the cause of property damage?

Cause determination relies on four coordinated analytical disciplines: field observation, construction document review, weather data correlation, and laboratory testing. Each informs the others, and conclusions drawn from any single dimension alone are rarely sufficient for a defensible causation opinion.

Site observations and damage patterns

The field investigation is the foundation of a cause and origin opinion. Damage pattern is often more informative than damage severity: where on a structure damage concentrates, how it distributes across surfaces, and what adjacent undamaged assemblies reveal about pre-storm conditions all contribute to the causation analysis.

Review of construction details and materials

Investigators evaluate original construction documents, applicable codes at the time of construction, and manufacturer installation requirements for the materials present. Fastener conditions, adhesive states, and material composition can corroborate or contradict storm causation.

Correlation with weather data

Site-specific weather reconstruction uses multiple data sources: National Weather Service (NWS) Storm Data, National Oceanic and Atmospheric Administration (NOAA) surface observation networks, Doppler radar archives, and independent spotter reports. Reconstructed wind speeds, hail sizes, and storm tracks are compared against damage thresholds for properly installed assemblies.

Testing and analysis methods

Laboratory analysis supports field observations where physical evidence requires further evaluation. Materials testing can identify fatigue, corrosion, and composition anomalies. Chain-of-custody documentation preserves the evidentiary integrity of specimens collected for analysis.

How do forensic engineers distinguish weather damage from construction deficiencies?

Property damage from storms rarely has a single causal thread. A wind event may be the trigger while an improper nailing pattern or degraded adhesive strip may explain why a roof failed below its rated design capacity. Investigators evaluate those interacting factors across four dimensions, each addressed in the sections below.

How does damage pattern analysis identify wind vs. installation problems?

American Society of Civil Engineers/Structural Engineering Institute (ASCE/SEI) 7-22, referenced by the 2024 International Building Code (IBC), partitions roof surfaces into pressure zones:

• Zone 3 at corners
• Zone 2 along perimeters
• Zone 1 across the field

Because wind-induced uplift is greatest at corners and perimeters, damage concentrated in those zones with an intact field is often consistent with wind loading. Think of it like water pressure against a dam: the edges bear the greatest stress first. Uniform damage across the field, without corner and perimeter concentration, may warrant closer examination of installation and material conditions.

Two on-site findings frequently suggest installation deficiency rather than storm performance. Shingle creasing without displacement may indicate the tab bent under uplift but held, pointing to degraded sealant rather than fastener failure. Missing shingles with nails still in the deck may suggest tab seal failure rather than fastener pull-through. Nails driven above the sealant strip (high-nailing) or through it are often identified as pre-existing installation errors, documented in post-hurricane field investigations including the FEMA Hurricane Michael report.

How does forensic meteorology reconstruct site-specific conditions?

NWS Storm Data and NOAA surface observation networks provide a starting point for weather reconstruction, but they may not resolve site-specific conditions without additional analysis.

A hailstorm cell may track two miles north of a property while leaving the site untouched; automated weather verification reports relying on radar algorithms often may not fully resolve that difference. Forensic meteorologists use Doppler radar data, spotter networks, and multiple independent observation sources to reconstruct conditions at the specific address on the specific date of loss.

Where damage is confined to cladding (the exterior skin of a building, including roofing, siding, and facade assemblies) and reconstructed wind speeds or hail sizes fall below standard damage thresholds for properly installed assemblies, the finding may indicate the presence of pre-existing deficiency or deferred maintenance. That assessment typically requires examining the physical record on the building.

What physical evidence indicates pre-existing conditions?

Fasteners outside the manufacturer’s designated nailing zone, adhesive strips with bonding fully released across the full strip length, and sealant cracked or separated from the substrate at window or wall penetrations are installation or maintenance conditions a storm may have exposed but is unlikely to have created. A forensic structural engineer evaluates these indicators against applicable standards and manufacturer requirements at the time of installation.

How do investigators distinguish deferred maintenance from storm damage?

Deferred maintenance differs from a construction defect in timing. A defect is typically present from installation; a maintenance failure develops over time. Investigators look for signs of progressive degradation: sealant hardened and separated across its full length, clogged drains with multi-season debris accumulation, and roof membranes thinned uniformly rather than fractured at discrete impact locations.

Maintenance records, or their documented absence, may carry significant evidentiary weight. When physical evidence suggests gradual degradation and records support a finding of unmet maintenance obligations, the storm may have been the occasion for visible damage rather than the sole cause.

How is structural damage evaluated after weather events?

Two conditions present recurring investigative challenges: hail damage, where physical evidence fades quickly and aging is frequently mistaken for impact, and foundation movement, where cracking attributed to a recent storm may reflect settlement that began well before the claimed event.

Distinguishing hail damage from aging and deterioration

Hail investigation begins with corroboration, not with the roof. The investigator looks first at reference surfaces: metal flashing, window frames, condenser fins, and junction boxes. Burnish marks (the clean circles left when a hailstone removes oxidation or surface grime) may help establish that hail fell at the property, may provide a rough estimate of stone diameter, and indicate directionality. Fresh marks have sharp edges and high color contrast; weathered marks lose that definition. Fractures that do not align spatially with burnish marks on adjacent surfaces may suggest the fractures predate the storm.

Functional hail damage to a shingle roof

Hail-caused damage to asphalt shingles centers on two conditions: a bruise (fracture of the reinforcing mat beneath the granule surface) and granule displacement sufficient to expose underlying bitumen. Granule loss without a mat bruise or bitumen exposure is among the conditions frequently misidentified in the field, as granules migrate naturally through thermal cycling, foot traffic, and weathering. That distinction may carry coverage implications depending on specific policy language and applicable case law.

When does foundation distress indicate pre-existing conditions?

Foundation movement from expansive soils, inadequate drainage, or poor subgrade preparation can produce cracking that a property owner attributes to a recent storm. Fresh crack faces commonly present clean edges and consistent color with no efflorescence; older cracks commonly show rounded edges, carbonation staining, and efflorescence from long-standing water migration. Diagonal stair-step cracking in masonry walls often indicates differential settlement that develops over months or years rather than in a single weather event.

Where prior inspection reports document earlier cracking, investigators compare those baselines against post-event observations to evaluate whether the damage is new or a continuation. That distinction may be determinative where coverage disputes turn on whether structural movement predated the policy period.

How does investigation methodology support defensible causation opinions?

A causation opinion is only as defensible as its methodology and records. Effective investigation generally involves structural engineering, materials science, forensic meteorology, and geotechnical disciplines coordinating under a shared evidentiary standard aligned to ASTM E2713-25 and ASCE forensic investigation guidance. Courts evaluate the underlying record as well as the conclusions it contains.

Documentation practices and expert opinion defensibility

Investigators maintain contemporaneous field notes, dated photographic logs, chain-of-custody records for laboratory specimens, and quantitative measurement records. A coordinated report integrating each discipline’s findings supports admissibility under FRE 702; without that integration, even technically sound root cause analysis opinions may be challenged on methodological grounds.

Why does cause determination matter for claims resolution?

Coverage decisions often depend on accurate cause attribution. Water intrusion from wind-force damage may fall within policy terms; intrusion through assemblies that failed due to inadequate maintenance or installation defects may not. Those distinctions are frequently contested , and outcomes may hinge on the technical analysis supporting each position.

Subrogation adds a second dimension. If a storm exposed a construction deficiency, its origin (design, specified materials, or installation workmanship) may determine whether a responsible third party exists. That analysis benefits from documentation rigorous enough to withstand Daubert/Kumho scrutiny of the construction defect investigation’s methodology.

How does Rimkus perform cause and origin investigations?

Rimkus approaches cause and origin investigations through coordinated, multidisciplinary teams drawing on structural engineering, forensic meteorology, materials science, and geotechnical expertise. Investigations follow documented methodologies aligned to ASTM E2713-25 and ASCE forensic engineering guidance, producing records intended to support admissibility under applicable evidentiary standards.

With 40+ years of experience and 100+ offices worldwide, Rimkus forensic engineers have evaluated property damage across wind and hail events, construction defect claims, deferred maintenance disputes, and concurrent causation matters. Field teams document conditions before repairs begin, coordinate laboratory analysis where physical evidence warrants, and integrate findings across disciplines into coordinated causation reports. Engage experts for cause analysis on active claims if you have questions.

Frequently asked questions

How do forensic engineers determine or apportion damage between storm effects and pre-existing construction defects when both contributed to a loss?

Investigators compare the pre-storm baseline condition, documented through prior inspection reports, maintenance records, and pre-event photographs, against post-event findings. The apportionment opinion is expressed to a reasonable degree of engineering certainty and supported by documented measurements that associate specific damage areas with specific causes.

What evidence is most useful after a storm or weather event?

Investigators benefit most from documentation captured before repairs begin: dated photographs of all affected assemblies, close-up images of fastener conditions and sealant states, and interior records of water intrusion locations and staining patterns. Those conditions change quickly, and the evidence they contain is rarely recoverable after emergency repairs start.

How does the 2023 amendment to FRE Rule 702 affect cause and origin expert testimony in property damage cases?

The amendment requires proponents of expert testimony to demonstrate by a preponderance of the evidence that opinions rest on sufficient facts or data and reflect a reliable application of valid methods. In concurrent causation matters, professional judgment alone is rarely sufficient; quantifiable support linking each damage attribution to documented methodology and field conditions is typically expected.