A self storage conversion turns an existing building, such as a warehouse, a closed store, a barn or a factory floor, into rentable units. Before you buy, confirm zoning, structure, fire code and truck access, then divide the total conversion cost by the rentable square feet you will get and compare that with the rent your market supports.
This is general information, not legal or engineering advice. Zoning, building and fire rules are local. Verify with your planning office, a licensed architect or engineer, and your attorney.
Why convert
Conversions can save time and money when the building is sound. You may already have a roof, walls, utilities, parking and sometimes a location that would be hard to permit as new. They also carry risk: old buildings hide problems, and an odd shape can waste space.
If you are weighing a conversion against new construction, run both in the feasibility calculator. Read how to start a self storage business for the larger picture.
Which buildings convert well
| Feature | Good | Problem |
|---|---|---|
| Floor | Level, strong slab | Slopes, cracks, drains in wrong places |
| Ceiling | 10 feet or more clear | Low ceilings, lots of pipes |
| Columns | Few, regular spacing | Many, irregular |
| Doors | Overhead doors or wide openings | None; walls to cut |
| Roof | Newer, dry | Leaks, old membrane |
| Access | Truck-friendly, wide approach | Narrow street, tight turns |
| Location | Near homes or traffic | Isolated, no signage |
| Utilities | Power, lighting, water available | Needs new service |
Big box retail, light industrial space, farm buildings and old schools are common candidates.
Step 1: Check zoning and permits first
Before you sign anything:
- Ask the planning office whether self storage is allowed at this address, and what approval it needs: a permit, a conditional use, a variance or a rezoning.
- Ask the building department about change of occupancy rules. A change from retail to storage may trigger code upgrades.
- Ask the fire marshal about sprinklers, alarms, exits, corridor width and unit door spacing.
- Ask about parking, signage, lighting and stormwater.
- Get the answers in writing, and make your purchase contract depend on approvals.
Rules vary a lot. One town welcomes conversions; another bans storage on main roads. Have your attorney review contingencies.
Step 2: Inspect the building
Hire a structural engineer or an experienced contractor. Look for:
- Roof condition and remaining life
- Floor load capacity (storage units can be heavy when filled)
- Moisture, mold, asbestos or lead in older buildings (ask your lender and attorney about environmental reports)
- Electrical service and panels
- Existing sprinklers and fire alarm
- Pests and structural damage
- Doors, windows and openings to seal
Treat what the inspection finds as price you pay, and negotiate. Add the cost to your budget.
Step 3: Design the unit layout
A good layout rents more square feet per building and keeps the aisle, door and column spacing practical.
- Measure the interior wall to wall, column to column.
- Choose corridor width. Wide enough for carts and fire code.
- Lay out units by size. Mix small, medium and large, based on local demand. See self storage unit sizes.
- Use columns smartly. Hide them in walls between units.
- Count rentable square feet. Divide by gross square feet to get your efficiency.
- Plan doors, lighting, access control, cameras and a place for the office or kiosk.
The unit mix calculator helps you test sizes and rents. Learn the terms NRSF and GSF.
Worked example (illustrative)
Say a 20,000 square foot warehouse has 5,000 square feet of corridors, mechanical space and office. The rentable area is 15,000 square feet, an efficiency of 75 percent. At $1.00 per rentable square foot per month and 85 percent occupancy, rent is 15,000 x $1.00 x 0.85 = $12,750 a month, or $153,000 a year. With $45,000 a year of expenses, NOI is $108,000. If the building price plus conversion costs $1,200,000, NOI divided by cost is 9 percent. Change the rent to $0.75 and NOI drops to $69,750 ($114,750 minus $45,000), or 5.8 percent. The $1.00 rent is a worked number, not a market figure. Check local rents with competitor calls and with a broker or appraiser.
Step 4: Build the budget
Request quotes for each line.
| Line | Notes |
|---|---|
| Purchase price | Plus closing costs, survey, title |
| Environmental and inspections | As recommended |
| Architect and engineer | Plans, permits |
| Demolition and cleanup | Existing partitions, fixtures |
| Partitions and doors | Per unit |
| Corridors and lighting | Often underestimated |
| Fire protection | Sprinklers, alarms |
| Electrical and HVAC | Especially if climate controlled |
| Roof and envelope repairs | From inspection |
| Paving and exterior | Parking, drive lanes |
| Gate, cameras, access control | See security and cameras |
| Signs, marketing, software | Opening costs |
| Contingency | Old buildings surprise people |
Convert the total to cost per rentable square foot. Compare that with new construction quotes. If you plan climate control, read climate controlled storage.
Step 5: Financing
Lenders review the building, the plan and your experience. The SBA lists real estate purchase, construction and renovation among eligible uses for its 504 program, which works through Certified Development Companies and lenders. Local banks may also lend. Terms vary. See self storage financing for questions to ask.
Step 6: Phase the work
Open part of the building early to start income:
- Finish the units that need the least work.
- Test your rents on the first group.
- Add more units as cash arrives.
- Adjust your mix based on what rents fastest.
Phasing lowers risk but adds construction disruption. Keep tenants away from active work areas, and tell your insurer.
Insurance and operations
Get an updated policy once the building is a storage property. See self storage insurance basics. Set up a lease, online rentals and autopay before you open; see writing a good self storage lease.
Common conversion mistakes
- Buying before the zoning answer is in writing
- Ignoring change-of-occupancy code upgrades
- Underestimating corridors and fire code
- Cutting too many small units that do not rent in your market
- Skipping a roof inspection
- No contingency line
- Pricing rents from hope instead of competitor calls
Checklist
- Zoning and fire marshal answers in writing
- Inspection by an engineer or contractor
- Layout with rentable square feet counted
- Budget from quotes and a contingency
- Rent assumptions checked against local competitors
- Financing questions asked of two lenders
- Insurance updated
- Software, lease and gate set up before opening
Typical conversion types
| Building | Strengths | Watch for |
|---|---|---|
| Closed retail or big box | Large clear span, parking, visibility | Roof size, sprinkler needs, columns |
| Warehouse or light industrial | Dock or overhead doors, truck access | Floor drains, oil stains, environmental history |
| Farm or barn | Cheap, rural fit | Structure, moisture, code upgrades |
| Old school or office | Many rooms and corridors | Low efficiency, small doors |
| Garages or sheds | Fast to add | Zoning, drainage, fire separation |
Phasing and cash flow
Many conversions start with the easiest part of the building, open it, and add more as cash arrives. Keep tenants away from work areas, keep fire exits clear, and ask your insurer before you open a partly finished building. Watch the lease-up carefully: new tenants should confirm that your mix matches demand before you build the rest.
Questions for your contractor
- What is your cost per unit and per rentable square foot, excluding the shell?
- What did you find behind walls and under floors in similar buildings?
- How do you handle changes in scope, and what do change orders cost?
- Who pulls permits, and who handles inspections?
- What warranty do you give on roofs, doors and partitions?
- What is your schedule, and what delays are common?
Get at least two bids with the same scope, and ask each for references on storage projects.
This is general information. Code and zoning vary by location, so verify with local officials and professionals.