Self-Storage Underwriting: The REPE Asset Class Explained

Self-storage has become one of the most institutionalized asset classes in real estate, and it shows up increasingly in REPE interviews because its underwriting mechanics differ meaningfully from multifamily or office. There's no loss-to-lease concept, revenue is driven by rate management rather than long-term leases, and the capital intensity is among the lowest in real estate. This guide covers how self-storage deals are underwritten, what metrics matter, and the specific traps interviewers plant in storage models.

Why self-storage is a distinct asset class

Self-storage differs from other REPE sectors in ways that change the underwriting:

The month-to-month lease structure means revenue can be repriced quickly, unlike multifamily where rent increases require turnover or renewal. This creates a different risk/return profile and a different modeling approach.

Revenue build: units, rates, and occupancy

Physical occupancy vs. economic occupancy

Self-storage has two occupancy metrics:

Physical Occupancy = Occupied Units ÷ Total Units
Economic Occupancy = Actual Revenue ÷ Potential Revenue at Street Rates

Economic occupancy is almost always lower than physical occupancy because many tenants pay below street rate (long-term tenants, promotional rates, employee discounts). Both matter: physical occupancy measures demand, while economic occupancy measures revenue capture.

Revenue calculation

Potential Revenue = Total Rentable SF × Street Rate per SF per Month × 12
Actual Revenue = Σ (Occupied Unit SF × Actual Rate per SF × 12)
Economic Occupancy = Actual Revenue ÷ Potential Revenue

Unlike multifamily, there's no GPR → vacancy → EGI bridge with loss-to-lease. Revenue is driven by:

• Street rate (the asking rate for new tenants)
• Actual rate (what existing tenants pay, often below street)
• Occupancy (physical units occupied)
• Rate increases (annual bumps to existing tenants, typically 5%-10%)

Rate management: the key operating lever

Self-storage operators increase revenue primarily through rate management, not lease-up:

Same-Store Revenue Growth ≈ Rate Increases + Occupancy Change + New Customer Premium

A stabilized facility at 90% physical occupancy can still grow revenue 5%-8% annually by raising rates on existing tenants and charging new tenants street rates. This is fundamentally different from multifamily, where revenue growth requires turnover to mark rents to market.

Interviewers test this: "How does a 95% occupied storage facility grow revenue?" Answer: rate increases on existing tenants + new tenants at street rate + ancillary income (insurance, locks, boxes).

Expense structure

Self-storage has among the lowest expense ratios in real estate:

Typical Expense Ratio: 30%-40% of revenue (vs. 35%-45% for multifamily)

No TI/LC, no leasing commissions for standard storage; tenants rent online or at a kiosk. This is a major cash flow advantage vs. multifamily or office.

Capital reserves are minimal: $0.10-$0.25/SF/year (vs. $250-$350/unit/year for multifamily).

Underwriting a stabilized self-storage acquisition

Going-in metrics

Going-In Cap Rate = Year-1 NOI ÷ Purchase Price
Revenue per SF = Total Revenue ÷ Total Rentable SF
NOI per SF = NOI ÷ Total Rentable SF
Expense Ratio = Operating Expenses ÷ Revenue

Benchmark these against comps and the operator's portfolio. A facility with $12/SF revenue and 35% expense ratio in a market where comps do $14/SF is either underperforming (value-add opportunity) or in a weaker submarket.

Debt sizing

Self-storage qualifies for favorable agency and CMBS financing:

Typical LTV: 65%-75% (stabilized)
Typical DSCR minimum: 1.25x-1.30x
Typical interest rate: Fixed, 5-10 year term, 25-30 year amortization
Debt Yield minimum: 8%-10%

Size debt on in-place NOI (not pro forma) for acquisition, same as multifamily. DSCR and LTV constraints bind similarly.

Exit assumptions

Exit Cap Rate: typically entry cap + 25-50 bps (conservative)
Exit Revenue: apply rate growth and occupancy assumptions
Forward NOI at exit: capitalized at exit cap rate

Self-storage exit caps have compressed significantly over the past decade as institutional capital entered the sector. Using a going-in cap from 2019 data without adjusting for current market conditions is a common modeling error.

Value-add in self-storage: expansion and optimization

Self-storage value-add differs from multifamily:

Expansion underwriting adds complexity: construction of new units on an existing site, phased delivery, and incremental revenue from new SF. Model expansion separately from the existing facility's stabilized cash flow.

Key metrics interviewers test

"What's the difference between physical and economic occupancy?" Physical = units occupied ÷ total units. Economic = actual revenue ÷ potential revenue at street rates. Economic is always lower because existing tenants often pay below street rate.

"How does self-storage grow revenue without lease-up?" Rate increases on existing month-to-month tenants (5%-10% annually), new tenants at street rate, and ancillary income (tenant insurance, merchandise). No loss-to-lease concept: every tenant can be repriced on 30 days' notice.

"Why is self-storage capex so low?" No unit interiors, no TI/LC, no leasing commissions. Concrete boxes with roll-up doors keep maintenance minimal. Climate-controlled units have higher HVAC costs but still far below multifamily per-unit capex.

"What's a good expense ratio for self-storage?" 30%-40% of revenue for a well-operated facility. Above 45% suggests operational inefficiency or an unusual cost structure. Below 30% may indicate deferred maintenance or missing expense categories.

"How do you underwrite an expansion?" Separate capital budget for new units, phased delivery schedule, incremental revenue at market rates, and combined DSCR on total facility (existing + new). Expansion is often funded by construction loan converted to permanent at stabilization.

Self-storage vs. multifamily in interviews

When an interviewer presents a self-storage deal, don't apply multifamily logic:

The cap rate bridge (revenue → expenses → NOI → value) still applies; the revenue build just looks different.

The takeaway

Self-storage is a REPE asset class with its own operating metrics, revenue drivers, and capital structure advantages. Interviewers test it because the month-to-month lease structure, rate-driven revenue growth, and low capex intensity produce a fundamentally different underwriting profile than multifamily or office. Know the metrics, avoid applying multifamily assumptions, and you'll stand out in any REPE process with storage exposure.