Converting an existing building to self storage

By [AUTHOR NAME] · Reviewed by [REVIEWER NAME], [ROLE] · Review date [YYYY-MM-DD]

Vacant big-box stores, warehouses and old factories can become climate-controlled storage. A conversion can open faster than a ground-up build because the shell already exists. It can also hide costs in the roof, slab, sprinklers and code upgrades. This guide shows how to screen a building, what to inspect, and how to compare it to building new.

What makes a good conversion candidate

Start with the building's bones. Interior walls and doors are cheap to add. Structure, height and access are expensive to change.

Screening a building
Factor	Good sign	Warning sign
Clear height	Room for a mezzanine or second level	Low ceilings limit you to one level
Floor slab	Sound slab able to carry new loads	Cracks, settling or unknown capacity
Column spacing	Wide, regular bays	Tight, irregular columns that waste space
Roof	Recent roof with life left	Leaks or end of life
Loading	Dock doors or space to add drive-up doors	No way to bring carts close to the building
Visibility	Frontage on a busy road	Hidden behind other buildings
Parking	Room for customer loading near entries	Shared lot with conflicts

Run demand first. A great building in a saturated market is still a bad deal. See our feasibility study guide.

Zoning and change of use

A new use usually triggers zoning review even if the building stays the same. Retail zones do not always allow storage. Check the use table and any design rules on visible doors.

Read what to check on self storage zoning before you sign a purchase or lease.

Building code and fire protection

Changing the use of a building usually triggers building code review. The local building department decides which upgrades apply. Ask for a pre-application meeting before you buy.

Fire sprinkler requirements are often the largest code item. Many jurisdictions adopt NFPA 13, published by the National Fire Protection Association. The local fire marshal decides what your building needs.

Confirm the occupancy classification the building official will apply.
Ask whether existing sprinklers must be upgraded for storage.
Check fire department access, hydrants and water supply.
Confirm exit paths and travel distances for the new layout.
Ask about fire separation between storage and any other tenants.
Ask what the energy code requires for added climate control.

Accessibility

A conversion still needs accessible units and an accessible route to them. The 2010 ADA Standards, Table 225.3, require 5 percent of spaces to be accessible for 1 to 200 spaces. Above 200 it is 10 plus 2 percent of units over 200. Accessible units must be spread across the different unit classes.

Inspect before you commit

Hire professionals during due diligence. Their reports drive your budget.

Structural engineer: slab, columns, roof framing and mezzanine capacity
Roofing contractor: condition and remaining life
Mechanical engineer: HVAC capacity for climate control and humidity
Fire protection engineer: sprinkler and alarm upgrade scope
Electrical review: service size for lighting, HVAC, gates and elevators
Phase I environmental site assessment
Survey and title review

The Phase I matters more for older industrial buildings. EPA explains All Appropriate Inquiries and notes ASTM E1527-21 can be used to meet it.

Plan the layout

Storage layouts follow simple rules. Keep corridors straight. Put the largest units near loading doors. Put small units deeper in the building and on upper floors.

Place the office and a loading zone near the main entry.
Plan cart storage close to each entry.
Plan elevators or freight lifts for upper levels.
Use existing dock doors for a covered loading area.
Consider drive-up units along exterior walls where code allows.

Build your mix with our unit mix guide. Count rentable square feet, not gross building area.

Run the numbers against building new

The key metric is cost per rentable square foot. Compare a conversion to a new build on the same basis.

Worked example (example inputs)

Conversion vs. new build per rentable square foot

These inputs are invented to show the math. They are not market data. Use real bids and appraisals.

Example inputs
Item	Conversion	New build
Building or land purchase	$2,000,000	$600,000
Construction and fit-out	$2,400,000	$4,800,000
Soft costs and contingency	$600,000	$600,000
Total cost	$5,000,000	$6,000,000
Gross square feet	80,000	75,000
Rentable share	75%	85%

Conversion rentable square feet: 80,000 x 0.75 = 60,000. Cost per rentable square foot: $5,000,000 / 60,000 = about $83.

New build rentable square feet: 75,000 x 0.85 = 63,750. Cost per rentable square foot: $6,000,000 / 63,750 = about $94.

In this example the conversion is cheaper per rentable foot. A larger sprinkler or roof bill could reverse that. Rerun it after every inspection report.

Compare against the line items in our cost to build guide.

Common conversion surprises

Older buildings rarely match their drawings. Budget time and money for what you find after demolition.

Slab areas that cannot carry a mezzanine without new footings
Roof drains and leaks hidden behind old ceilings
Undersized electrical service for HVAC and elevators
Asbestos or lead paint in older materials
Sprinkler mains too small for the new layout
Accessibility upgrades at entries, restrooms and parking

Carry a contingency line in your budget for these items. Base its size on your inspectors' findings, not a rule of thumb.

Owning versus leasing the building

Some operators lease a building and convert it. That lowers upfront cost but adds landlord risk. A long lease term with renewal options protects your investment in fit-out.

Lease term long enough to recover fit-out costs
Renewal options at known terms
Landlord approval for alterations and signs
Clear split of roof, structure and parking lot repairs
Right of first refusal if the landlord sells

Have a real estate attorney review any lease before you spend on design. Lenders will also review the lease if you finance the fit-out.

Financing a conversion

Lenders treat conversions as construction projects. Expect them to want inspections, bids and a lease-up plan.

SBA's 504 page lists renovation of existing buildings as an eligible use. See our financing guide for loan options.

Set a realistic schedule

Map out the conversion in phases before you close. Typical phases are due diligence, design, approvals, permits, construction and lease-up. Ask each consultant how long their part takes, and add the hearing calendar. Order long-lead items early, such as HVAC equipment, elevators and partition systems. A conversion that opens in sections can start renting sooner. Ask the building official whether partial occupancy is possible while work continues elsewhere in the building.

Frequently asked questions

Is a conversion faster than building new?

Often, because the shell exists. Code upgrades, approvals and HVAC work can still take months.

Do I need sprinklers?

The local building and fire officials decide. Ask them before you buy, because sprinkler upgrades can be a major cost.

Can I convert part of a building?

Yes, many owners do. Ask about fire separation from other tenants and shared parking conflicts.

Can I use an SBA loan for a conversion?

SBA lists renovation of existing buildings as a 504 use. Eligibility depends on SBA rules and the lender.

How many accessible units do I need?

Under ADA Table 225.3, 5 percent for 1 to 200 spaces, then 10 plus 2 percent of units over 200.

What kinds of buildings convert well?

Former retail stores, warehouses and light industrial buildings are common candidates. Look for sound structure, good height, loading access and road visibility. Offices with small floor plates and many columns are usually harder to lay out efficiently.