Sources & Methodology

How we cite, scope, and verify the figures on this site.

Every headline figure on fathomassurance.com is directional unless explicitly marked as verified at the asset level. Directional means the figure is sourced from a named study or institutional series and is cited to indicate scale and direction, not to substitute for asset-level underwriting.

Each entry below lists the figure as it appears on the site, the named source, the publication year, the study population or scope, and a one-line methodology note. Where a figure is drawn from a study population that does not match the multifamily commercial real estate context, we say so plainly.

96% / 72%

Fewer water claims and lower claim severity associated with inline leak-detection shutoff devices.

Source: LexisNexis Risk Solutions — Single-Family Escape-of-Water Correlation Study
Year: 2020
Population: 2,306 single-family homes with an active inline leak-detection device, benchmarked against a control group of approximately 1.3 million single-family homes drawn from LexisNexis insurance-claim records.
Methodology: Single-family homeowner study. Findings are correlational at the single-family level. Multifamily applicability is directional, not measured. We cite this figure to indicate the order-of-magnitude effect of inline shutoff devices, not to assert an identical effect on commercial multifamily portfolios.

75%+

Real-terms rise in multifamily property insurance premiums, 2019–2024.

Source: Federal Reserve Bank of Dallas
Year: 2026
Population: Multifamily property insurance premium series, deflated to real terms over the 2019–2024 window.
Methodology: Reported as a CPI-deflated change in multifamily property insurance cost. Cited as a directional indicator of structural premium pressure, not an asset-level forecast.

23% / 27% / 412%

Year-over-year change in multifamily property insurance deductibles, 2021 through 2024.

Source: Federal Reserve Bank of Minneapolis
Year: 2025
Population: Multifamily operator survey responses on year-over-year deductible movement.
Methodology: Self-reported deductible change at the operator level. Cited as evidence that deductible escalation has materially outpaced premium escalation in the most recent cycle.

>50%

Share of operating-expense inflation since 2020 that some multifamily operators attribute to property insurance increases alone.

Source: Federal Reserve Bank of Minneapolis
Year: 2025
Population: Multifamily operator survey responses on drivers of operating-expense inflation since 2020.
Methodology: Operator-attributed share, not an audited decomposition. Cited to indicate that insurance has moved from a line item to a primary driver of NOI erosion at the operator level.

70.2%

Share of apartment firms naming water damage as their #1 reported claim type.

Source: National Multifamily Housing Council / Multifamily Dive
Year: 2023
Population: Apartment firms responding to the NMHC industry insurance survey.
Methodology: Self-reported claim frequency ranking by apartment-firm respondents. Reflects what operators report, not insurer loss-cost data.

Property-level modeling

Carriers are modeling non-weather water and freeze risk at the property level rather than as a book-wide tax.

Source: ZestyAI
Year: 2024
Population: Carrier product documentation on non-weather water and freeze risk scoring.
Methodology: Cited as evidence that the underwriting frame for interior water is shifting from book-wide to asset-level. Reflects vendor product positioning, not an independent loss study.

Verification requests

Underwriters, lenders, and analysts may request the underlying citations, study PDFs, or scope clarifications for any figure on this page. Reach the assurance desk through the contact form and reference the entry number above.