How do I know if I’m allowed to build an ADU on my property? How big can it be?

ADU requirements vary by city and jurisdiction. Your property’s zoning, lot size, setbacks, and other local regulations can determine whether an ADU is allowed and what size it can be. Maximum ADU size requirements also vary by location. We can help you understand the regulations that apply to your property and determine what may be possible before moving forward with design and permitting.

How many rounds of revisions are included in the conceptual phase until I am satisfied with the design?

The number of revisions included during the conceptual design phase depends on the scope of your ADU project and the design package. We work closely with you to refine the design and make sure the layout, features, and overall concept align with your goals and property. Any revision limits or additional design services will be discussed with you upfront before moving forward.

Detached ADU and Backyard Cottage Builder in Tampa Bay

A well-finished 750 sq ft one-bedroom detached ADU in St. Petersburg or South Tampa currently rents for $1,400–$1,900 per month on a 12-month lease. Smaller 500 sq ft studios rent for $1,100–$1,500. Larger 900 sq ft two-bedroom units can clear $2,100 in strong submarkets like Old Northeast, Hyde Park, and Seminole Heights.

Against a $165,000 all-in build for a 750 sq ft unit at $1,600/month average rent: gross annual rent $19,200, operating costs $3,800, net operating income $15,400, cash-on-cash return 9.3%, estimated property value lift $80,000–$130,000, years to full ROI on rent only 10.7, years to full ROI on rent plus value lift 3–5.

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Detached vs. Garage Conversion vs. Attached: Which Is the Right Rental?

At 700 sq ft: Detached ADU costs $130,000–$180,000, rents $1,500–$1,900/month, highest tenant privacy, highest appraisal impact, 9–13 month timeline. Garage conversion costs $80,000–$140,000, rents $1,200–$1,600/month, medium privacy, 5–8 month timeline. Attached ADU costs $100,000–$150,000, rents $1,300–$1,700/month, lowest privacy, 7–11 month timeline. For a pure investment-return thesis, detached tends to win on lifetime rent collected, appraisal impact, and privacy — which is what lets you charge the upper end of market. Garage conversion wins on cash-on-cash return for the first few years because the initial basis is lower.

Florida's Rental Rules That Actually Affect Your ADU

A granny flat in Tampa Bay is almost always one of three forms: 1. Detached backyard granny flat: Its own small building in the back or side yard. Most privacy, highest cost, tends to appraise best. Typical size 500–950 sq ft. 2. Garage conversion granny flat: Your existing attached or detached garage reframed as a living unit. Lower cost, faster permit, but requires code-compliant egress, kitchen, bathroom, and HVAC. 3. Attached granny flat (addition): New square footage added to the main home with its own entrance, kitchen, and bathroom. Shares a wall with the primary. Often the best answer when the lot is tight. Every one of these has to meet Florida Building Code, 2023 Edition (8th). That means hurricane-rated openings, wind-uplift connectors, and a roof system rated for the wind zone your address sits in. In most of Pinellas County, that is Exposure C or D and a 140–150 mph ultimate design wind speed.

Design Decisions That Drive Rent in Tampa Bay

Three factors separate a top-of-market detached ADU from a bottom-of-market one in the same neighborhood:

1. Natural light and ceilings: 9 ft ceilings rent for more than 8 ft. Window area above 15% of floor area noticeably improves tour-to-application conversion.

2. Private outdoor space: A small patio or fenced entry court is worth $100–$200 per month over an ADU with no private outdoor area. For tenants, the difference between a small apartment and a home is often a single door out to their own patch of grass.

3. Full kitchen, not kitchenette: Tenants pay market rent for a 30-inch range; they pay below-market for a two-burner cooktop. The incremental cost of a full kitchen vs. a kitchenette is $3,000–$6,000 at build and adds $150–$250 to achievable monthly rent.

Frequently asked questions

Garage Conversion

Detached ADU

ADU Permitting

Granny Flat

Mother-in-law suite

ADU Feasibility Study

ADU size requirements vary by city and jurisdiction. The minimum or maximum size may depend on factors such as your property’s zoning, lot size, setbacks, and local regulations. Beyond what is allowed, the ideal ADU size depends on how you plan to use the space and the needs of your household. We can help you understand the applicable requirements and determine a practical size for your ADU before moving forward with design and permitting.