What Is an ADU? (The Tiny House in Your Backyard)

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ADU means "accessory dwelling unit." It is a small home you build on the same land as your main house. In St. Petersburg, FL, the easiest way to make one is to change your garage into a cute apartment. You can rent it to long-term tenants or use it for family. Many St. Pete homeowners call it a "garage-to-ADU conversion."

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Quick 2026 Cost Snapshot for St. Pete Homeowners

• Average size: 400 sq ft (two-car garage)

• Average total cost: $120,000

• Cost per square foot: $275 – $450

• Low-cost basic finish: $62,000

• High-end luxury finish: $180,000

• Average rent in St. Pete: $1,550/month

• Payback with long-term rent: 13 years

• Payback with Airbnb (30-day min): 9 years

Prices went up 4–6% from 2025 because lumber, impact-rated windows, and mini-split AC units cost more now.

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Where Your Money Goes (Simple Breakdown)

Hard Construction (76%) = $91,200

• New walls, floor, and ceiling

• Impact-rated windows and doors

• Tiny kitchen & full bath

• Mini-split AC & water heater

• Electrical panel upgrade

Design & Engineering (8%) = $9,600

• Architectural drawings

• Structural letter

• Energy calculations

Permits & City Fees (5%) = $6,000

• City of St. Pete plan review

• Water/sewer tap fee

• Fire safety check

Contingency (7%) = $8,400

• Fixes for termite damage or cracked slab

• Moving a wall 2 inches because you changed your mind

 

St. Pete Impact-Fee Waiver (Free Money!)

Pinellas County still waives transportation & school impact fees for ADUs under 750 sq ft. A normal 400 sq ft garage conversion saves you about $7,100 in 2026.

 

How Long Does It Take? (Calendar for Busy Parents)

• Pre-app consult: 2 weeks

• Plan review: 5–6 weeks

• Building the unit: 14–18 weeks

• Final inspection & CO: 1 week
  Total = 5–6.5 months from "let’s do it" to "here are your keys."

 

Financing 101 (No Selling Your Boat)

1. Fannie Mae HomeStyle® Reno Loan – 6.9% 30-year fixed; roll closing costs in.

2. HELOC – 6.7% variable; pay interest only first 10 years.

3. Cash – fastest close, biggest discount from subs.

Most St. Pete homeowners use the renovation loan because it covers both construction and finish materials.

 

Rent Money Math (Cash in Your Pocket)

Long-term tenant:
$1,550/month × 12 = $18,600 per year
$120,000 ÷ $18,600 = 13-year payback

Airbnb (30-day minimum stay rule):
$120/night × 65% occupancy × 365 = $28,470 per year
$120,000 ÷ $28,470 = 9-year payback

After the loan is paid off, that rent becomes pure passive income for retirement, college tuition, or more beach days.

 

Is My Garage Good Enough? (Quick Checklist)

✓ 20 ft wide inside (fits bed, bath, kitchen)
✓ 7.5 ft ceiling (we can raise trusses if needed)
✓ 200-amp panel space (or room for a sub-panel)
✓ Alley or side access (separate entrance = higher rent)

If you check three out of four, you’re golden. Call us and we’ll confirm for free.

 

ROI When You Sell (Appraisal Magic)

Florida Realtors say homes with legal ADUs sell for 18% more per square foot. On a $425k St. Pete bungalow, that’s about $76k extra—covering 63% of your conversion cost the day you list.

 

Frequently Asked Questions – St. Pete Garage-to-ADU 2026

Q1: Do I need a permit?
A1: Yes. St. Pete treats garage conversions as new dwellings. We draw the plans and pull the permit for you.

Q2: Will I lose my parking?
A2: City code wants one parking spot for the ADU and one for the main house. We can stripe a tandem driveway or add a paver pad for about $2,500.

Q3: Can I put a full kitchen?
A3: Absolutely. We install a mini-split, 20-amp outlets, and either a 24-inch range or two-burner cooktop.

Q4: Do I get a separate electric meter?
A4: Duke Energy adds a meter for ~$850. Water and sewer tie into your existing line—no extra tap fee thanks to the 2026 waiver.

Q5: How do I pay for this?
A5: Most owners use a renovation loan or HELOC. We give you a fixed-price scope so your lender can close quickly.

Q6: Can I Airbnb the unit?
A6: Yes—St. Pete allows short-term rentals with a 30-day minimum stay. Average $120/night, 65 % occupancy = ~$28k gross per year.

Q7: Will my taxes go up?
A7: Yes, but only on the improvement value—about $1,200–$1,800 extra per year. The rental income covers that easily.

Q8: Do I have to raise the floor?
A8: Not unless you’re in a FEMA V-zone. We use a moisture barrier and insulated sub-floor—saves you ~$8k.

Q9: How soon can you start building?
A9: Once permits are issued, 14–18 weeks. Site visit to keys = about 6 months total.

Q10: What if I change my mind mid-build?
A10: No problem. Our contingency line covers small changes; bigger ones get a written change order so you always know the number.