Self-Storage Tenants Don’t Move Like They Used To. That Changes How You Underwrite Every Deal.

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The most important number in self-storage right now is not a street rate. It’s not a cap rate. It’s not construction starts.

It’s 18 months.

That’s how long the average tenant now stays.

The shift, in two data points

Oakside Companies published their 2026 market trends report this month. Their finding: average tenant stays have lengthened to 18-19 months. In 2017, the same number was 9 to 14 months. In some markets, it’s now over 24 months.

Placer.ai’s Anchor report — “Stalled Moves, Sticky Tenants” — found the consequence of longer tenancy: street rates for 10x10 units are down 10-15% year over year, but in-place rents are running 15.6% higher than advertised rates.

Same sector. Same set of tenants. Opposite directions.

Here’s what that means. The tenant who pays $180 for a 10x10 is not paying the same rate you’d quote someone who walked in off the street today. They’re paying less — sometimes much less — because they’ve been there for 18 months and the market has moved around them. And because they’re not moving, they’re not shopping around. They’re sticky.

That 15.6% gap is the structural consequence of longer tenure.

Why this happened — two mechanisms, not one

First: housing turnover stalled. People who refinanced at 3% in 2021 are not selling that house. People who moved during the pandemic didn’t move back. When fewer people move, fewer people churn their storage unit. The Placer.ai report calls this “the move-in, move-out feedback loop.” It’s not temporary. It’s demographic.

Second: the tenant mix itself changed. In 2017, most units held household goods — a three-month rental bridge during a move. Today, a growing share holds vehicles, boats, and RV storage — a subscription that renews monthly whether the owner uses the vehicle or not. The MMCG Invest data (5x supply gap, 12.5% CAGR in vehicle storage) is the demand-side story for this shift. The Oakside tenure data is the supply-side consequence. Same trend, different lens.

Neither of these is cyclical. Neither reverses when the economy turns. In fact, a downturn that freezes housing turnover further would lengthen the average stay.

What this means for underwriting

The old pro forma assumed a tenant stayed 9 to 12 months. The model baked in annual turnover: two weeks vacancy between tenants, cleaning cost, re-renting cost, concession to attract a new mover. On a 100-unit facility with $150 average rent, that turnover cost roughly $15,000 to $25,000 a year in vacancy and opex.

At 18 months, turnover drops by a third. Vacancy between tenants shrinks. The unit stays full longer at a rate that — while lower than market — is still cash-flow positive and growing.

We’ve seen this inside the portfolio of operators we work with. A facility that projected 85% occupancy at a $170 average rate in 2020 is now running 91% occupancy at a $195 average rate in 2026 — and the blended rate is still 10% below what its market would support. The tenure shift is already inside the numbers. Most pro formas just haven’t been updated to reflect it.

Here’s the deal. If you underwrote a deal with the old 9-month tenure assumption, the stabilized NOI you calculated is low. Not wrong — conservative. The 18-month tenure reality means lower turnover costs, higher lifetime tenant value, and more room to push in-place rates without triggering a move-out. That gap is the upside the old model doesn’t capture.

Run the numbers.A tenant who stays 18 months instead of 9 is worth roughly $900 more in lifetime rent on a $150 unit — and costs roughly $150 less in turnover. Multiply that across 100 units. That’s real money the old model missed. Run the numbers. Then run them again.