Quick answer: A guest house is permitted only where zoning allows it and a permit supports it. In unincorporated St. Lucie County, the Land Development Code allows one guest house per single-family dwelling in certain districts, on a building permit and a notarized statement, and the county's affidavit says it may not be used for seasonal or annual rental. In Port St. Lucie, I could not confirm the current zoning text, and a third-party summary suggests a guest house may need a special exception. Florida's vacation rental rules limit local bans on short-term rentals, but they do not by themselves make a guest house rentable under zoning.
Guest houses, in-law suites and accessory dwelling units use overlapping names, and the names do not decide the legal question. What decides it is the local zoning code, the permit record, the lender's rules and any HOA documents. This article covers the Florida law that applies, the St. Lucie County and Port St. Lucie rules I could confirm, and the limits of what I found.
What state law says
Florida law defines an accessory dwelling unit as a living unit with a separate kitchen, bathroom and sleeping area (s. 163.31771(2)(a)). A local government "may adopt an ordinance to allow" such units in areas zoned for single-family use, and nothing in the statute requires a city or county to allow them (s. 163.31771(3)). I found no amendment to that section in the 2026 statute text. Whether a guest house is an accessory unit under local code is a separate question.
Florida's vacation rental statute provides that local governments may not prohibit vacation rentals or regulate how long or how often they are rented, except for ordinances adopted on or before June 1, 2011 (s. 509.032(7)(b)). The statute defines a transient public lodging establishment as a property rented to guests more than three times a year for periods under 30 consecutive days, or advertised as regularly rented for such periods (s. 509.013(4)(a)1). Those rules address short-term rental operations. They do not override a zoning limit on the use of a particular structure, and whether a zoning bar on an accessory unit is preempted is a legal question I did not resolve.
City of Port St. Lucie
I could not retrieve the city's zoning text, so I cannot give you the current rule from primary code. The city's special exception application, revised in January 2026, says the City Council approves special exceptions under Sec. 158.260, and that an approval expires after one year unless a site plan or permits are obtained. A third-party zoning summary says accessory dwelling units are not a listed use in the RE or RS-1 to RS-3 districts, that guest houses are allowed in RE only by special exception on lots over one acre, and that a guest house cannot be rented or used as a separate dwelling. That summary is not the city code, and I have not verified it. Another third-party site quotes a city planning FAQ as saying there is no blanket citywide ADU allowance. Ask the city in writing before you assume a guest house is permitted.
Unincorporated St. Lucie County
The county's Land Development Code Section 7.10.04 covers guest homes. According to the county's guest house affidavit, revised in 2024, guest homes are allowed in the AG-1, AG-2.5, AG-5, R/C, AR-1, RE-1 and RE-2 districts. The Growth Management Director may authorize one guest house per single-family dwelling, on a building permit and a notarized statement. The affidavit says: "Under no circumstances shall the guest house be used for rental purposes seasonal or annual." The excerpt I read does not state the size or setback rules, and I did not retrieve the full code or confirm whether the section applies only to unincorporated areas.
Permits matter for the sale and the insurance
Under s. 553.79(1)(a), it is unlawful to construct, alter or repair a building in Florida without first obtaining a permit. If a guest house was built or converted without one, ask the seller for the permit history and any final inspection records. A 2021 secondary article warns that unpermitted work can complicate an insurance claim, but I did not find a Florida or Office of Insurance Regulation source confirming that. Ask your insurance agent how the structure is classified and covered.
Lending
Fannie Mae's guidance on accessory units says an ADU should always be considered legal if it is allowed under the current zoning code. If zoning does not allow it, a property may still qualify if the lender confirms that the existence of the unit will not jeopardize a future property insurance claim (Selling Guide B2-3-04). Ask your lender how the specific structure will be treated.
HOA rental rules
If the property is in an association, Florida's statute lets associations bar rentals for periods under six months and bar more than three rentals a year (s. 720.306(1)(h)). For restrictions adopted after July 1, 2021, the limit applies to owners who acquire title after the restriction is adopted. The governing documents, not the statute alone, will decide whether a guest house may be rented in that community.
Advertising and fair housing
Do not call a guest house "legal," "rentable" or an "ADU" unless the code and the permits support the description. Florida's real estate advertising rules prohibit false or misleading statements (Fla. Admin. Code 61J2-10.025(1)). Rental copy also may not exclude families with children. Florida's Fair Housing Act covers familial status (s. 760.23), and the federal Fair Housing Act does too (42 U.S.C. 3604). A "no children" limit in an ad is not acceptable.
What to bring to the professionals
Zoning, HOA, insurance, lending and tax questions need the right professional. The planning department can confirm zoning in writing. An attorney can read the HOA documents and the rental terms. Your insurer can confirm coverage, and a CPA can explain tax treatment if the guest house produces income.
Questions buyers ask about guest houses
Can I build a guest house on a Port St. Lucie lot?
I could not confirm the city's current rule from primary code. A third-party summary says guest houses may require a special exception on larger RE lots. Ask the Planning and Zoning Division in writing before you rely on it.
Can I rent a guest house?
In unincorporated St. Lucie County, the guest home affidavit says it may not be used for seasonal or annual rental. In Port St. Lucie, a third-party summary says it cannot be rented as a separate dwelling. Whether state vacation rental rules affect a local zoning bar is a legal question for an attorney.
Must cities allow ADUs?
No. Section 163.31771(3) is permissive, so whether a city allows an accessory dwelling unit is a local decision.
Does an unpermitted guest house affect insurance or a sale?
For insurance, I did not find a Florida source confirming a denial rule, though a secondary article warns of one. For a sale, a lender may review an accessory unit that zoning does not allow, under Fannie Mae's guidance. Ask both the insurer and the lender.
Can an HOA ban rentals or guest houses?
The governing documents control. Section 720.306 limits how rental restrictions can be adopted and enforced, including the minimum rental period and the number of rentals per year.
Talk with William. Buying or building with a guest house in mind? Send me the address. I will help you list the zoning, permit and HOA questions to put in writing before you commit, and connect you with the right professional for each one. Call or text (772) 800-2274 or send a message.
General information, not zoning, legal, insurance, lending or tax advice. Zoning, permit and rental rules are local and change. Confirm them in writing with the city or county planning department, and confirm HOA rental limits with an attorney. Statute and code references are as reviewed on October 20, 2026. William Merchant, REALTOR®, RE/MAX Gold. Each RE/MAX office is independently owned and operated. Equal Housing Opportunity.
Sources
- Florida Statutes 163.31771, Accessory dwelling units (2026)
- Florida Statutes 509.032, Preemption of vacation rental regulation (2026)
- Florida Statutes 509.013, Definitions for public lodging establishments (2025)
- Florida Statutes 553.79, Permits (2025)
- Florida Statutes 720.306, Rental restrictions in homeowners' associations (2025)
- Fannie Mae Selling Guide B2-3-04: Special property eligibility considerations
- RISMedia: How making home improvements without a permit can affect your homeowners insurance (2021, secondary)
- City of Port St. Lucie: Special exception use application (revised January 2026)
- Building Club: Port St. Lucie ADU rules (third-party, secondary)
- CityRuleLookup: Port St. Lucie ADU rules (third-party, secondary)
- St. Lucie County: Guest house affidavit (revised 2024), LDC Section 7.10.04
- Florida Statutes 760.23, Discrimination in housing (2025)
- 42 U.S.C. 3604, Discrimination in the sale or rental of housing
- Fla. Admin. Code 61J2-10.025, Advertising rules for real estate licensees
