Converting an attached two-car garage (approximately 400–500 sqft) into finished living space costs $20,000–$60,000 in Georgia and $25,000–$70,000 in Florida. This includes insulation, drywall, flooring, electrical upgrades, HVAC extension, and at minimum one window. Adding a bathroom increases the budget by $8,000–$15,000. Adding a kitchenette adds $5,000–$12,000. Per square foot, garage conversions run $40–$120 — significantly less than new construction because the shell (foundation, walls, roof) already exists.
| Component | Cost Range | Notes |
|---|---|---|
| Insulation (walls + ceiling) | $2,000–$4,000 | Garage walls are typically uninsulated. R-13 minimum for walls, R-30 ceiling. |
| Drywall & paint | $3,000–$6,000 | Fire-rated drywall required on shared walls with main house. |
| Flooring | $2,000–$5,000 | Garage slabs slope toward the door. May need self-leveling compound. |
| Electrical | $2,000–$5,000 | Garages have minimal circuits. Need dedicated circuits, outlets, lighting. |
| HVAC | $3,000–$8,000 | Mini-split is most common. Extending ductwork if existing system has capacity. |
| Window/door replacement | $2,000–$8,000 | Garage door removed. Framed wall with window(s) and possibly a man door. |
| Bathroom (if added) | $8,000–$15,000 | Requires plumbing through slab. Adds significant value. |
A detached Accessory Dwelling Unit — built from the ground up in your backyard — costs $100,000–$200,000+ for a 400–800 sqft unit in Georgia and Florida. This is full new construction: foundation, framing, roofing, all mechanical systems, kitchen, bathroom, and finishes. The per-sqft cost ($150–$275) is lower than a primary home because ADUs are simpler structures, but the fixed costs of permits, utility connections, and site work make very small units disproportionately expensive.
Before spending a dollar on design, verify your property’s zoning allows the conversion or ADU you’re planning. Zoning determines everything: whether an ADU is permitted, maximum size, setback requirements, parking requirements, and whether it can be rented. Atlanta passed ADU-friendly ordinances in 2019, making detached ADUs legal in most residential zones. Unincorporated Fulton, DeKalb, and Cobb counties have more restrictive rules. Florida’s Live Local Act (2023) expanded ADU permissions statewide, but local implementation varies. Always check with your city or county planning department — not your HOA alone — before proceeding.
A finished garage apartment or detached ADU in Metro Atlanta rents for $800–$1,400/month depending on location, size, and finishes. In Central Florida, comparable units rent for $900–$1,500/month. At a conversion cost of $40,000–$60,000 and monthly rent of $1,000–$1,200, the payback period is 3–5 years. Long-term, the ADU also increases your property value by $50,000–$100,000+ in most Metro Atlanta markets. The AARP ADU resource center provides state-by-state zoning summaries and planning guides.
Bowser Construction Group handles garage conversions and ADU construction across Georgia and Florida. Zoning research, structural upgrades, full MEP systems, and finished living space.
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