If you have an attached or detached garage and a driveway you can live without, you might be sitting on one of the highest-ROI residential projects available: the garage conversion ADU. Foundation, walls, roof, and most of the utilities are already there. The conversion is mostly interior work — which means it's faster, cheaper, and less disruptive than building from scratch.
What a garage conversion actually costs
| Conversion Type | Typical Size | All-In Cost |
|---|---|---|
| 1-car attached garage | 200–280 sqft | $55K – $95K |
| 2-car attached garage | 400–500 sqft | $80K – $140K |
| 2-car detached garage | 400–500 sqft | $95K – $160K |
| Garage + small addition | 500–700 sqft | $130K – $200K |
Where the budget actually goes
- Insulation, drywall, flooring (the existing slab usually needs leveling and finishing): $15K–$30K
- Plumbing rough-in and fixtures (full kitchen + bathroom): $18K–$35K
- Electrical upgrade and rewire: $8K–$15K
- HVAC (mini-split is most common): $5K–$10K
- New windows and an exterior entry door: $4K–$10K
- Kitchen cabinets, counters, appliances: $8K–$20K
- Permits, design, project management: $8K–$20K
Permits: this is non-negotiable
An unpermitted garage conversion is a legal landmine. You can't legally rent it, you can't refinance against it, you have to disclose it on sale (and it tanks your appraisal), and your homeowner's insurance may not cover it. Don't do this.
- Zoning approval / ADU permit application (city and county).
- Building permit for the conversion itself.
- Mechanical, electrical, and plumbing sub-permits.
- Final inspections + certificate of occupancy.
In Florida, most building departments process garage-to-ADU building permits in 6–12 weeks once the application is complete; state law (s. 553.792) sets a 30-business-day clock for most single-family building permit decisions. Zoning or ADU approval, where your city requires it, adds time on top.
Layout decisions that make or break the rental
1. Put the bathroom near existing plumbing
If your garage shares a wall with the main house's bathroom or kitchen, put the new bathroom on that wall. You can often save $5K–$10K in plumbing.
2. Front entry, not garage door
Replace the garage door with a wall, windows, and a real front entry. Renters don't want to live behind a roll-up door. Most inspectors won't approve it as habitable space if the original garage door remains operable.
3. 9-foot ceilings if possible
Garages often have higher ceiling height than you realize. Don't add a dropped ceiling. Tall ceilings are the single biggest 'this feels like a real apartment' upgrade you can make.
4. Separate utility metering (or sub-metering)
If you can run a separate electric meter, do it. If not, install a sub-meter. Including utilities in rent caps your upside and creates billing fights.
What does a garage ADU actually rent for?
In our Florida market, a permitted, finished 1-car garage conversion (around 250 sqft as a studio) rents for roughly $1,000–$1,400/month long-term, depending on metro. A 2-car conversion (400–500 sqft as a 1BR) rents for roughly $1,200–$2,200/month. Short-term rental rates in tourist zones can be higher but come with more management and local STR rules.
ROI math (illustrative)
- Build cost: $110,000 all-in (typical 2-car attached conversion)
- Monthly rent: $1,500
- Annual gross: $18,000
- Annual NOI (after ~25% expenses): $13,500
- Yield on cost: 12.3%
- Payback period: ~8.1 years
- Plus: a permitted conversion may add $40K–$80K of property value at appraisal (not guaranteed)
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Frequently asked
Will I lose property value by removing my garage?
Usually not — in many markets a permitted ADU often adds more value than the garage it replaced. ADU comps are increasingly available to appraisers, who may value permitted, finished space at habitable rates rather than garage rates.
Do I need to add a parking space if I convert my garage?
Depends on the city. Some Florida cities waive or reduce replacement parking for ADUs under their own codes; others still require an alternative on-site space. Check locally.
Can I convert just half my garage?
Yes — partial conversions are common. The math gets tighter because you still pay the fixed costs (permits, utility runs, kitchen) but rent a smaller unit.
How long does a garage conversion take?
On typical Hivesta projects, from signed contract to certificate of occupancy: 4–7 months. Permitting is the longest phase.
Keep reading
ADU Cost in Florida: What to Budget
A complete breakdown of accessory dwelling unit (ADU) costs in Florida, including detached, attached, garage conversions, and prefab options — with permits, timelines, and ROI math.
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