An accessory dwelling unit (ADU) is a second, smaller home built on the same lot as an existing single-family house. In Florida, ADUs are now one of the fastest legal paths to add housing, generate rental income, or house family without buying another piece of land. Here's how they work, what they cost, and where the law is heading.
An accessory dwelling unit — also called a backyard cottage, granny flat, guest house, in-law suite, or casita — is a fully independent home that sits on the same parcel as a primary residence. It has its own kitchen, bathroom, and entrance. It can be detached (a standalone structure in the backyard), attached (an addition), or converted (a garage or basement). Tooly builds a detached prefab ADU: a 264 sq ft hurricane-rated cottage, delivered and installed in about 15 weeks.
The honest answer most builders give is "$115,000 to $300,000+, depending on size, finishes, site work, and contractor." Tooly's answer is different: $85,000, fixed, furnished, finished. One price, no surprises. Full breakdown on the ADU cost page.
Most homeowners use a HELOC, cash-out refinance, or construction-to-perm loan. Some Florida credit unions and specialty lenders offer ADU-specific products that underwrite against future rental income rather than current equity. We track the active lenders on our financing page.
Probably yes, but it depends on your city and county. Florida cities like Miami, Orlando, Tampa, and St. Petersburg have already opted in under Statute 163.31771. HB 313 would make ADUs by-right statewide if it passes. The Florida ADU laws page tracks the current rules and the moving legislation.
In most Florida jurisdictions, yes — long-term rentals are typically permitted, short-term (Airbnb-style) rentals are sometimes restricted. A Tooly rents in most metros for $1,200–$1,800/month. Math on the rental-income page.
$1,200–$1,800/month in most Florida metros. A $85,000 unit producing $15,000/year in rent yields roughly 15% before financing costs — well above most rental-property cap rates.
See the rent math →Adult children priced out of the for-sale market. Aging parents who need proximity but not a shared roof. Independence on the same lot.
Talk to us →A finished, permitted ADU typically adds 25–35% to a Florida single-family property's appraised value — often more in supply-constrained metros.
See the numbers →Every Florida city sets its own rules within the state framework — max ADU size, setback requirements, owner-occupancy rules, parking minimums. Click into your metro for the specifics:
One of the most ADU-friendly cities in the state. The Miami 21 code permits accessory dwelling units on most T3 (single-family) lots.
Miami ADU rules →The largest ADU-active metro by permit volume. Tampa allows ADUs on most residential lots, with size and setback limits.
Tampa ADU rules →Orlando permits ADUs citywide under its 2023 ADU ordinance, with streamlined permitting for compliant designs.
Orlando ADU rules →Florida's largest city by area. ADUs are permitted in many residential zones, with rules that vary by district.
Jacksonville ADU rules →St. Pete updated its ADU ordinance in 2023 to broaden where ADUs are permitted as-of-right.
St. Petersburg ADU rules →Palm Beach County and several of its municipalities permit ADUs under the Workforce Housing program.
Palm Beach ADU rules →Florida is moving toward making ADUs by-right on most single-family lots — meaning local zoning boards could not block them. HB 313 is the bill to watch. The mandate is targeted for December 1, 2026.
If it passes as written, three things happen:
For homeowners thinking about a Tooly, the practical implication: reserve and permit now so your unit is in the ground when the demand wave hits. Full timeline on the Florida ADU laws page.
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