Underwriting With Climate in the Denominator

EPISODE DESCRIPTION
Every ratio that matters in real estate — cap rate, DSCR, yield on cost — is a number divided by a number. Most investors are telling a strong story with the numerator while quietly hoping the denominator doesn't move. In a climate-repricing market, the denominator is moving. Episode 5 of Climate-Ready Real Estate Investing builds the framework for putting it back where it belongs.

Host Jamie Wolf walks through a 500-unit Class B Sun Belt multifamily acquisition — $75 million purchase, 5.5% going-in cap, 6% financing, initial DSCR of 1.18 — and shows exactly what happens when climate risk is placed in three denominators: debt service, exit value, and risk-adjusted NOI.

The standard model produces a 9% levered IRR. The climate-in-the-denominator model — using NAA Premium Pulse March 2026 insurance benchmarks, 12% insurance escalation, flat NOI reflecting current Sun Belt market conditions, and a 6.75% exit cap rate — produces negative equity. The same deal. The same asset. Different assumptions. The gap between those two outcomes is Signal 4, the valuation gap, made concrete on a single transaction.

The episode closes with a three-minute pre-LOI test that every investor can run before committing capital, and the four strategic responses when the denominators don't hold.

Episode Summary
A 500-unit Sun Belt multifamily acquisition produces a 9% levered IRR under standard assumptions and negative equity under climate-adjusted assumptions — same asset, same purchase price, different denominators. The difference comes from three line items: insurance trajectory using current NAA Premium Pulse data ($1,500/unit at 12% CAGR), flat NOI reflecting today's supply-pressured market, and a 6.75% exit cap rate reflecting a thinned buyer pool. This episode builds the Three Denominators framework and the pre-LOI stress test that shows you which deals have margin and which ones don't before you sign.

Key Takeaways

1. • The Three Denominators framework: Climate risk must live in (1) debt service — the DSCR denominator, (2) exit value — the cap rate denominator, and (3) risk-adjusted NOI — the return denominator. Not in a footnote, not in a sensitivity table.

   • NAA Premium Pulse, March 2026: Houston multifamily insurance now exceeds $1,200/unit annually. Insurance is no longer a marginal line item — it is a defining component of operating strategy in 2026.

   • First Street Foundation 2025 National Risk Assessment: multifamily properties in high-risk markets trade at a 25% discount to comparable assets in low-risk areas.

   • The deal model — standard vs. climate-adjusted:
     
     
     • Purchase: $75M, 5.5% cap, NOI $4.125M, loan $48.75M at 6% / 30yr, annual DS ~$3.507M, Year-1 DSCR 1.18

     • Standard model: Year-5 NOI $4.64M, exit at 5.75% = $80.7M, equity proceeds $35.4M on $26.25M investment, levered IRR ~9%

     • Climate model: insurance base $750K ($1,500/unit) at 12% CAGR, utilities at 5%, NOI flat, exit at 6.75%

     • DSCR trajectory under climate assumptions: Year 1: 1.18 → Year 2: 1.15 → Year 3: 1.13 (below 1.15 covenant floor) → Year 4: 1.10 → Year 5: 1.07. Year-3 covenant breach without a weather event.

     • Climate exit: NOI flat at $4.125M at 6.75% cap = $61M. Loan balance ~$45.4M. Equity proceeds ~$15.7M on $26.25M investment. Negative levered IRR. Capital destroyed.

   • The $19.6M terminal value haircut (24% of original exit) comes from repricing — not a hurricane, not vacancy — from a buyer pool that priced the climate liability into their cap rate.

   • Houston is documented as the nation's fastest-sinking major city. Subsidence compounds flood risk on assets engineered for a different ground elevation than they'll sit on in five years.

   • Three-minute pre-LOI test: Identify actual current insurance cost per unit (NAA Premium Pulse is a named, free source). Run at 10–12% CAGR for 10 years. Utilities at 5%. Exit cap 100 bps wider. Hold NOI flat if any supply pressure. Check Year-3 DSCR. If it falls below 1.15: reprice, restructure, or walk.

   • Four strategic responses: (1) Walk or renegotiate when the deal stops penciling. (2) Use the denominator framework as a portfolio construction tool — not a deal-killer. (3) Lenders will run this math within 18 months; bring it to them first. (4) Climate-in-the-denominator analysis is your edge with institutional LPs who are actively screening for it.

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• Next episode: The End of the 30-Year Mortgage Assumption

References & Sources Cited

• National Apartment Association (NAA) Premium Pulse, March 2026 — Houston multifamily insurance exceeds $1,200/unit annually; 26% insurance increases documented in 2023
• Minneapolis Federal Reserve Bank — multifamily housing insurance survey: Gulf Coast wind/flood CAGR documented in range of 14–45% (referenced across series)
• First Street Foundation 12th National Risk Assessment (Feb 2025): multifamily in high-risk markets trades at 25% discount to low-risk — bisnow.com May 2026
• NAA/IREM/BOMA I/E IQ 2024: insurance costs increased 26.2% on average in 2023 — yieldpro.com Jan 2025
• Minneapolis Fed survey (March 2025): multifamily premiums doubled 2021-2024, rising 14% / 22% / 45% in successive years
• Wall Street Oasis practitioner forum: Class B Houston renewal quotes $850-$1,500/unit; Class C actuals $2,300-$2,500/unit
• Axios Houston (May 2025): Houston documented as nation's fastest-sinking major city — peer-reviewed study in Nature
• CBRE (Q2 2024): multifamily property values fell 11.1% in Houston driven by insurance costs

DISCLAIMER
Climate-Ready Real Estate Investing is an independent intelligence briefing. We synthesize publicly available research, industry reporting, and primary data sources — sometimes with the assistance of AI-enabled analytical tools — into commentary and analysis on the trends shaping real estate, climate risk, and the long-term durability of communities. The goal is to surface patterns and questions that investors, lenders, insurers, policymakers, and industry participants may wish to consider.

The views expressed are analysis and commentary, not personalized advice, and the material may contain errors, omissions, or interpretations that differ from other analyses. Nothing in this publication constitutes investment, financial, legal, tax, or other professional advice. Companion interactive dashboards (including the CRDF Signal TrackerTM and the CRDF Deal Stress TestTM ) are illustrative tools; any examples or archetypes referenced are composites drawn from publicly observable market data, not specific named asset...

Climate-Ready Real Estate Investing is an independent intelligence briefing. We synthesize publicly available research, industry reporting, and primary data sources — sometimes with the assistance of AI-enabled analytical tools — into commentary and analysis on the trends shaping real estate, climate risk, and the long-term durability of communities. The goal is to surface patterns and questions that investors, lenders, insurers, policymakers, and industry participants may wish to consider.

The views expressed are analysis and commentary, not personalized advice, and the material may contain errors, omissions, or interpretations that differ from other analyses. Nothing in this publication constitutes investment, financial, legal, tax, or other professional advice. Companion interactive dashboards (including the CRDF Signal TrackerTM and the CRDF Deal Stress TestTM ) are illustrative tools; any examples or archetypes referenced are composites drawn from publicly observable market data, not specific named assets or transactions. Listeners and readers should conduct their own due diligence and consult qualified professionals before making decisions.