Self-storage underwriting differs from multifamily and other commercial real estate in important ways. The unit isn't an apartment or a tenant lease — it's a small storage compartment rented month-to-month with no rental history. The rate isn't fixed in a 12-month lease — it's adjustable in real time. The expense base is much lower than multifamily. Understanding these differences is the key to underwriting storage correctly.

This lesson walks through the storage underwriting process step by step.

What to request from the seller

For any storage acquisition, request:

Current rent roll — every unit, size, current rate, occupancy status, customer move-in date
Trailing 12-month operating statement (T-12)
Historical financials — last 3 years
Site plan — showing all buildings, units, and amenities
Unit mix — count of units by size category
Rate matrix — current asking rates by unit size
Occupancy history — physical and economic occupancy by month for last 24 months
Move-in / move-out reports — customer turnover data
Property tax records — current and historical
Insurance binder — current premium
Service contracts — security, landscaping, pest, internet
Capital expenditure history — what's been done recently
Software / management system info — what's the current operator using?
Marketing data — Google reviews, search rankings, advertising spend

The rent roll and unit mix are the most important — they tell you what you're buying.

Reading the rent roll

The storage rent roll has different columns than a multifamily rent roll.

Key columns

| Column | What it tells you | |---|---| | Unit number | Specific unit | | Unit size | Square feet (e.g., 5×5, 5×10, 10×10, 10×20) | | Type | Drive-up, climate-controlled, parking | | Status | Rented, vacant, reserved | | Customer name | If rented | | Move-in date | When customer started renting | | Current rate | Monthly rent in $ | | Asking rate | Current advertised rate for an empty unit of this size | | Days delinquent | If applicable | | Insurance enrollment | Tenant insurance subscription |

What to calculate from the rent roll

Physical occupancy:

Rented units / Total units = Physical occupancy

Storage facilities target 88-94% physical occupancy. Below 85% suggests problems. Above 95% suggests under-pricing (you should raise rates).

Square footage occupancy:

Rented SF / Total SF = SF occupancy

Often slightly different from unit occupancy because larger units may have different occupancy rates.

Economic occupancy:

Actual revenue / Maximum potential revenue = Economic occupancy

This accounts for free rent, discounts, and any unit at below-market rate. Often 5-10 points below physical occupancy.

Rate per SF (in-place):

Total monthly rent / Total rented SF = $/SF/month

The blended rate per square foot tells you what current customers are paying. Compare to asking rate to identify rate gap.

Rate per SF (asking):

Asking rates × unit count weighted by SF = Blended asking $/SF

The asking rate is what new customers pay. The gap between asking and in-place rates is your immediate value-add opportunity.

Rate gap analysis:

(Asking rate - In-place rate) / In-place rate = Rate gap %

A 15-25% rate gap is typical for an under-managed facility. Closing this gap through ECRI (covered in Lesson 5) is the easiest way to grow NOI.

Red flags in the rent roll

Many long-tenured customers at very old rates
Wide gap between in-place and asking rates that the operator hasn't been closing
Many vacant climate-controlled units (high-margin space sitting empty)
High delinquency
Move-ins concentrated in one period (artificial occupancy boost)
"Free unit" customers (friends, family, employees)
Owner-occupied units

The unit mix

Different unit sizes serve different customers and rent at different price points.

Common storage unit sizes

| Size | SF | Typical use | $/SF/month (avg) | |---|---|---|---| | 5×5 | 25 | Small boxes, seasonal items | $1.50-$2.50 | | 5×10 | 50 | Apartment closet contents | $1.20-$1.80 | | 10×10 | 100 | Studio apartment contents | $1.00-$1.40 | | 10×15 | 150 | 1BR apartment contents | $0.90-$1.20 | | 10×20 | 200 | 2BR house contents | $0.80-$1.10 | | 10×25 | 250 | 3BR house contents | $0.75-$1.00 | | 10×30 | 300 | Large house, vehicles | $0.70-$0.90 | | Climate-controlled | varies | Premium product | +25-50% |

What the unit mix tells you

A facility with a balanced unit mix (mix of sizes from 5×5 to 10×20) serves a broad customer base.

A facility heavy in 10×30 drive-up units in a suburban residential market may be poorly positioned (residential customers want smaller units).

A facility heavy in 5×5 lockers in an industrial area may be poorly positioned (industrial customers want larger units).

The right unit mix depends on the trade area's demand profile.

Unit mix analysis

Calculate:

% of total SF by size category
% of total revenue by size category
Occupancy rate by size category

If 5×10 units are 95% occupied while 10×30 units are 70% occupied, the facility has too many large units. Future expansion or unit subdivision should focus on smaller units.

Some operators subdivide oversupplied larger units into smaller units to better match demand. This is a value-add tactic.

Rate analysis

Storage rates change frequently. The rate strategy is a major NOI driver.

Current rates vs market rates

For each unit size, compare:

Your current asking rate
Comparable facilities' asking rates (drive the comps, check their websites)
Online aggregator pricing (SpareFoot, StorageCafe show market rates)

If your rates are below market, you can raise them. If they're above market, you'll struggle to lease vacant units.

In-place rates vs market rates

Even if asking rates match market, in-place rates may lag if:

Customers haven't received recent rate increases
Operator has been timid about rate increases
Old promotions have created below-market customers

This gap is the biggest opportunity in storage value-add.

Specials and discounts

Storage operators commonly offer:

"First month free" (essentially 50% off the first 2 months)
"$1 first month"
"50% off first 3 months"
Seasonal discounts

These promotions reduce effective rate. Verify what specials the seller has been running and how it affects effective revenue per occupied unit.

Reading the T-12

The storage T-12 has a familiar income/expense structure but with storage-specific lines.

Income lines

Rental income — base unit rent (the biggest line)
Other income — administrative fees, late fees, lien sale proceeds
Tenant insurance — sold to customers (high margin)
Retail sales — locks, boxes, packing supplies
Truck rental — U-Haul or similar partnerships
Storage protection plans — alternative to tenant insurance

For a well-run facility, other income can be 10-20% of total income.

Expense lines

Storage expenses are simpler than multifamily:

Property taxes — typically the largest line
Insurance — second largest in Florida
Property management — 5-7% of gross income for third-party
Payroll — on-site manager (1-2 employees)
Utilities — electric (lights, climate control), water
Repairs and maintenance — minimal vs multifamily
Marketing — Google ads, online aggregators
Office supplies — minimal
Software / management system — $500-$2,500/month
Bank / merchant fees — credit card processing

Total expenses for a stabilized facility typically run 30-40% of effective gross income.

Expense ratio benchmarks

| Facility type | Expense ratio | |---|---| | Class A institutional | 30-35% | | Mid-quality professional | 35-40% | | Mom-and-pop tired | 40-50% | | Newly built lease-up | 50%+ |

If you're buying a mom-and-pop facility at 45% expense ratio, the value-add includes both raising revenue and reducing expenses (renegotiate insurance, change software, reduce payroll waste).

Florida-specific T-12 considerations

Insurance inflation — verify current premium with your own broker, not the seller's old policy
Property tax reset — Year 1 will reset to sale price; project conservatively
Storm preparation costs — periodic spending on hurricane prep
Air conditioning costs — for climate-controlled units, electric bills are higher in summer

Building the pro forma

Year 1 underwriting

Income:

In-place rents from rent roll
Apply ECRI plan: typically 8-12% rate increases on existing customers
New move-ins at current asking rates
Realistic occupancy: 88-92% physical
Other income at industry-standard rates (insurance attachment, late fees)

Expenses:

Property tax reset
Insurance current quote
Property management at your operator's rate
All other expenses based on T-12 with growth assumption

Result: Year 1 NOI

Years 2-5

For value-add deals, model:

ECRI plan — annual rate increases on existing customers (8-12%/year typical)
New customer rate growth — 2-4% annually
Occupancy stabilization — gradually approach mid-90s if currently lower
Expense growth — 2-3% annually
Optional capex: expansion, climate-controlled conversion, security upgrades

For stabilized facilities, model lower rate growth (3-5%) and expense inflation.

Sale year

Exit cap rate: 25-50 bps above going-in cap (conservative)
Sale price: Year 5 NOI / Exit cap
Sale costs: 1-3%
Loan payoff: Remaining balance
Equity proceeds: Net to investors

Returns calculations

Target returns for storage value-add:

Year 1 cash-on-cash: 5-8%
Stabilized cash-on-cash: 10-14%
IRR: 14-22%
Equity multiple: 1.7-2.2x over 5 years

For stabilized institutional storage:

Year 1 cash-on-cash: 6-8%
IRR: 9-12%
Equity multiple: 1.5-1.7x over 5 years

Storage-specific underwriting questions

Beyond standard CRE underwriting, ask:

What's the rate gap? (in-place vs asking; asking vs market)
How long has the current owner held it? (long-tenured owners often haven't pushed rates)
What software does it use? (modernization may be needed)
What's the customer acquisition strategy? (mostly drive-by? Mostly online?)
What's the Google review rating? (critical for online-driven leasing)
Are there nearby competing facilities? (check supply pipeline)
How is climate-controlled vs drive-up performing? (which is your growth segment?)
What's the auction history? (delinquency and collection patterns)
What's the tenant insurance attachment rate? (room to grow if low)
Is there expansion land? (future development upside)

Common storage underwriting mistakes

Trusting in-place rates — many properties have huge rate gaps that aren't immediately apparent
Missing competition — not checking nearby facilities and their rates
Ignoring the Google review angle — bad reviews kill leasing in storage
Aggressive ECRI assumptions — pushing rates too fast causes excessive move-outs
Underestimating insurance — Florida specifically
Property tax reset oversight — sale-time tax reset Year 1
No expansion analysis — missing the development upside on excess land
Underestimating turnover impact — even storage has some turnover and lease-up time
Wrong unit mix assumptions — what worked elsewhere may not work here
Ignoring online presence — modern storage requires modern marketing

What to take away

Storage underwriting starts with the rent roll, unit mix, and rate matrix
The rate gap (in-place vs asking) is the biggest value-add opportunity
Unit mix affects both revenue and customer fit
Storage T-12 has lower expense ratios than multifamily (30-40% typical)
Florida-specific items: tax reset, insurance, hurricane prep
Year 1 NOI projections should be conservative on occupancy and ECRI
Stress-test rate growth, occupancy, and exit cap assumptions
Storage value-add returns: 14-22% IRR is achievable; stabilized 9-12%
Common mistakes include trusting in-place rates, missing competition, and aggressive ECRI

Next lesson: the mom-and-pop value-add strategy — how to find under-managed facilities and unlock their hidden value.

Underwriting a Self-Storage Facility