Convert an Office Building into Apartments
Commercial Office Building → Apartment Building
Convert an underutilized commercial office building into residential apartments — a growing trend as remote work reshapes real estate demand in city centers.
Cost Range
$200,000 – $1,000,000
Timeline
26–78 weeks
Materials Cost
$172,000
Permits Cost
$37,500
Steps
Feasibility Study and Zoning
Hire a development consultant to assess viability. Verify zoning allows residential use or apply for a variance. Evaluate the floor plate — buildings under 80 feet wide convert best for natural light.
Estimated time: 30 days
Architectural Design and Unit Layout
Design apartment layouts maximizing window access. Each unit needs a kitchen, bathroom, bedroom, and living area. Plan shared hallways, stairwells, and elevator access per residential code.
Estimated time: 45 days
Structural Modifications
Add floor penetrations for residential plumbing stacks. Reinforce as needed for new partition walls and bathtub loads. Cut new window openings if the existing facade allows.
Estimated time: 30 days
Plumbing Infrastructure
Run new plumbing risers for kitchens and bathrooms in each unit. Install individual water heaters or a central hot water system. This is typically the most expensive and disruptive phase.
Estimated time: 45 days
Electrical, HVAC, and Fire Safety
Rewire for individual metering per unit. Convert commercial HVAC to residential systems. Upgrade fire safety with residential sprinklers, smoke detectors, and carbon monoxide detectors in every unit.
Estimated time: 45 days
Unit Build-Out and Finishes
Frame walls, install drywall, flooring, kitchen cabinets, appliances, bathroom fixtures, and lighting in each unit. Install interior doors and closets.
Estimated time: 60 days
Common Areas and Final Approvals
Finish hallways, lobby, mailroom, laundry room, and any amenity spaces. Pass all inspections and obtain certificate of occupancy for residential use.
Estimated time: 30 days
Materials
| Material | Est. Cost | Required |
|---|---|---|
| Plumbing Infrastructure (per unit average) | $8,000 | Required |
| Electrical Rewiring (per unit average) | $5,000 | Required |
| HVAC Conversion | $50,000 | Required |
| Kitchen Cabinets and Appliances (per unit) | $6,000 | Required |
| Bathroom Fixtures (per unit) | $3,000 | Required |
| Flooring (per unit) | $2,000 | Required |
| Fire Safety System Upgrade | $30,000 | Required |
| Drywall and Framing (per unit) | $3,000 | Required |
| Common Area Finishes | $25,000 | Required |
| Elevator Modernization (if needed) | $40,000 | Optional |
Permits
Change of Use Permit
Required for commercial-to-residential conversion. May require planning commission or city council approval.
$10,000
Building Permit
Comprehensive permit covering structural, mechanical, plumbing, and electrical work across the building.
$25,000
Fire Department Review
Full review of fire safety systems, egress, and sprinkler compliance for residential occupancy.
$2,000
Certificate of Occupancy
Final approval to occupy the building as residential units.
$500