The Cartersville Garage Conversion That Had to Pencil as a Rental

The owners wanted rental income from an unused detached garage and had seen online figures suggesting $35,000 would do it.

Those figures almost never include the systems that make a unit legal to rent: egress, insulation, HVAC, and a code kitchen and bath.

The slab was sound but had no vapor barrier and sloped toward the door — fine for cars, not for finished flooring.

The existing electrical was a single 30-amp feed shared with the house. A rentable unit needed its own service and panel.

No plumbing existed on site. The nearest sewer connection was 42 feet away, and that trench was the largest single line item nobody's online estimate included.

• ✦Build it as a permitted, legal dwelling or don't build it. We walked them through the county requirements before contracting.
• ✦Level the slab with self-leveling compound over a vapor barrier rather than pouring new — a $4,000 decision instead of $16,000.
• ✦Separate 100-amp service, mini-split HVAC sized to the envelope, and a compact but full kitchen so the unit rents as a real one-bedroom rather than a studio.

1. Weeks 1–2 — Permits and site work

   Permit issued, sewer and water trenched 42 feet, slab prepped and leveled over vapor barrier.

2. Weeks 3–5 — Shell and systems

   Framing including an egress-compliant bedroom window, spray foam at the roof deck, separate service and panel, mini-split lines, full plumbing rough-in.

3. Weeks 6–7 — Drywall and prep

   Rough inspections passed, drywall hung and finished, doors and trim.

4. Weeks 8–10 — Kitchen, bath, finishes

   Cabinetry, quartz, tile shower, LVP flooring, appliances, lighting and paint.

5. Week 11 — Final inspection and turnover

   Certificate of occupancy, systems walkthrough, and a rental-ready punch list.

• ✦Legal, separately metered one-bedroom ADU delivered for $88,000 — not the $35,000 the internet promised, and not a unit that fails an inspection either.
• ✦Leased within three weeks at $1,800 per month, roughly a 24% gross annual return on construction cost.
• ✦The permitted certificate of occupancy also means the square footage counts at appraisal.