ADU Construction in St. Petersburg: What LanCo Construction Builds and Knows
An accessory dwelling unit — whether it's an apartment over a detached garage, a backyard cottage, or an in-law suite carved out of the main house — is a common request among homeowners in Pinellas County. LanCo Construction has worked as a builder in St. Petersburg since 1986 and has completed ADU projects in the area, including a detached garage with a full apartment above it on 29th Avenue North, and a one-bedroom garage apartment with its own kitchen, bath and entry at a custom home project in the Old Northeast on 6th Avenue NE.
Since July 2022, the City of St. Petersburg has allowed ADUs on most single-family lots, though eligibility depends on zoning. In "NT" districts, a lot must be at least 4,500 square feet. In "NS" districts, the minimum is 10,000 square feet, unless the property sits on an alley or corner. The city offers a free ADU Map Look-up tool to confirm eligibility, and LanCo Construction checks this before any design work begins. Notably, the city does not require the owner to live on the property — both the main house and the ADU can be rented out, though a Business Tax Certificate is required for rental units, and any applicable HOA rules still apply.
Size limits in St. Petersburg cap an ADU at 800 square feet or 67% of the main home's size, whichever is smaller. This applies whether the unit is detached, an attached addition, or a conversion of existing space. Every ADU must function as a complete home, with its own kitchen, bathroom, and code-compliant exit. A detached unit also has to match the architectural style, materials, roof, and windows of the main house, and one additional off-street parking space is required. Separate electric and water meters, along with a separate mailing address, are permitted.
Choosing Between a Garage Apartment, Backyard Cottage, or In-Law Suite
The right configuration often depends on the lot. A detached garage with an apartment above makes efficient use of a small footprint by combining two uses in one structure, though it's more structurally involved since the garage walls and foundation need to support a second floor. A backyard cottage is typically the more straightforward option when there's open yard space. An in-law suite — created through an addition or a conversion of existing space — is often the lower-cost route since the structural shell already exists. LanCo Construction's garage additions and conversions work covers the structural side of these projects.
Flood zone status affects design choices as well. A new detached ADU within a Special Flood Hazard Area must be built elevated, like any new structure in that zone. For conversions, the city limits remodeling work to 49% of the home's value under the FEMA substantial-improvement rule, which applies to renovations throughout Pinellas County. That threshold is frequently the deciding factor between converting existing space and building a new detached unit.
Permitting, Rental Rules, and Other Pinellas County Jurisdictions
An ADU is permitted and inspected as an independent dwelling rather than an accessory structure. New construction requires signed and sealed architectural or engineered plans with energy calculations, along with a survey or site plan. Stormwater management — gutters, rain leaders, and an underdrain directing water to the street — is also required. Plans are submitted through the city's ePlan system, with review currently quoted at 3–5 business days. Permit fees for an 800-square-foot, one-bath unit run roughly $1,000 including impact fees. A licensed residential or general contractor is required unless the homeowner qualifies as an owner-builder; LanCo Construction manages the application, plan review process, and inspections.
Short-term rental of an ADU is restricted: St. Petersburg's residential districts set a 30-day minimum rental term, with shorter stays allowed only three times per year. Outside city limits, rules vary by jurisdiction — Gulfport, Seminole, and the beach communities each set their own lot minimums, size limits, and coastal restrictions, with some beach towns applying stricter standards than St. Petersburg. For properties outside the city, LanCo Construction checks the applicable ordinance before design work begins.
Some properties may also qualify for financial assistance. Homes within the South St. Petersburg Community Redevelopment Area, where household income is under 120% of the area median, may be eligible for the city's Affordable Residential Property Improvement Grant, which can reimburse up to 40% of eligible ADU construction or conversion costs, subject to tenant income limits if the unit is rented.
