An accessory dwelling unit — an ADU, or what most people here still call an in-law suite, granny flat, or backyard cottage — is a second, self-contained home on a lot that already has one. Florida law defines it as “an ancillary or secondary living unit, that has a separate kitchen, bathroom, and sleeping area, existing either within the same structure, or on the same lot, as the primary dwelling unit” (s. 163.31771, F.S.).
The question everyone actually asks is whether they can build one and rent it out. In Central Florida the answer changes depending on which side of a city line your house sits on — and the differences are not small. Here is what all five publish, read out of their own codes.
First: Florida Does Not Require Anyone to Allow ADUs
You will read that Florida now requires local governments to permit ADUs by right, with a compliance deadline. Treat that carefully. The operative statute is permissive: a local government “may” adopt an ordinance to allow ADUs in any area zoned for single-family residential use. It sets no deadline, it does not override local zoning, and it does not prevent a county from requiring you to live on the property.
Bills that would mandate ADUs by right have been filed in recent legislative sessions. A filed bill is not law. We track them; we would not design your project around one. What governs your project today is your local code.
The Short Version
Five jurisdictions, read out of their own codes. Note that they do not even agree on what to call one: Osceola's code says “Accessory Living Unit” (ALU) or “Guest Home,” not ADU.
| Jurisdiction | Owner must live on site? | Homestead? | Size cap | Min. rental term | Variance available? |
|---|---|---|---|---|---|
| City of Orlando | No | Not stated | 500–1,000 sq ft by lot size; 700 in Historic Districts | Under 30 days restricted | Not stated |
| Unincorp. Orange | Yes | Yes — to permit at all | Not published; set at zoning review | Not published | Not stated |
| Unincorp. Seminole | Yes | Not stated | 35% of main residence or 1,000 sq ft, whichever is less (A-3/A-5/A-10) | 30 days | No — not even considered |
| Unincorp. Osceola (“ALU”) | Not stated as such | Yes — to rent it out | Lot <1 ac: lesser of 60% or 1,000 sq ft A/C. Lot ≥1 ac: 60%, no sq ft cap | Long-term only; no short-term | Yes — Board of Adjustment |
| Unincorp. Lake | Yes — recorded restriction | Not stated | 1,200 sq ft or 70% of principal's A/C area, whichever is greater | Not stated | Not stated |
Every cell is drawn from that government's own published text. “Not stated” means the rule is not published where the others publish theirs — it does not mean the answer is no. Read the size column carefully: Osceola takes the lesser of its two figures and Lake takes the greater, which is why Lake is the most permissive on size in the metro and Osceola among the tightest on a small lot. Confirm with the jurisdiction before you design.
City of Orlando: The One That Allows a Rental ADU
Orlando is the outlier here, in the direction most homeowners hope for. Its ADU page says the same person or entity must own both the main house and the ADU, but that “either unit may be owner-occupied or rented long-term”. You do not have to live there.
Eligibility starts with zoning: “If your zoning category starts with R-1, R-2, R-3, MXD, O-1, O-2 or PD, you may be eligible.” Size runs 500 to 1,000 square feet depending on whether your lot meets the minimum for the larger unit — in R-1 that is 6,000 sq ft for a 500 sq ft ADU and 9,000 sq ft for a 1,000 sq ft one. Historic Districts cap it at 700 square feet, and in every case the ADU must be smaller than the main dwelling. The main house needs one parking space behind the front-yard setback, and an ADU over 500 square feet needs one more. Short-term rentals under 30 days require separate registration and are not allowed in all situations.
Unincorporated Orange County: Homestead Only
This is the one that surprises people, because so many “Orlando” addresses are actually here. Orange County's ADU permit page states that ADUs “may only be permitted on properties that qualify as homestead property” and are “not permitted on non-homestead properties”. The primary dwelling and the ADU “must remain under the same ownership at all times,” and “the property owner must occupy either the primary dwelling or the ADU at all times.”
Read together, that closes the investment case: you may build an ADU and put a tenant, a parent, or an adult child in one of the units, but you have to live in the other. The County recognizes three configurations — an attached ADU (an addition to the primary unit), an alteration ADU (converting existing space, which is the garage-conversion path and usually the cheapest), and a detached ADU. Plans go through the County's Fast Track online portal, zoning has to approve the use before permitting, and “a licensed contractor will be required to accept permit issuance,” though an owner-builder may act as contractor under the exemption in F.S. 489.103(7)(a).
Unincorporated Seminole County: The Most Detailed Code
Seminole publishes the most specific ADU rules of the three, in Sec. 30.6.1.3 of its Land Development Code, and three of them are worth knowing before you spend anything on design.
- Owner-occupancy and a 30-day floor. “Either the principal dwelling or the ADU shall be occupied by the owner,” the two cannot be subdivided into separate ownership, and ADUs “shall be rented or leased for a minimum period of thirty (30) days.” No short-term rental, at all.
- No variances. “The Board of Adjustment shall not consider variances related to ADU size, or minimum area and width of any lot where an ADU is proposed.” If the lot does not qualify, there is no appeal — so measure first.
- Impact fees turn on an affidavit. If the ADU is used for affordable rental purposes, impact fees are waived or reduced, but the permit application must include an affidavit attesting the unit will be rented at an affordable rate, and the County “will require deed restrictions or other agreements.” Without that affidavit, impact fees are assessed at the normal schedule.
The size rule is the one most often quoted wrong, because it is really two rules. In the A-3, A-5, and A-10 districts ADUs are permitted by right, capped at “thirty-five (35) percent of the gross floor area of the main residence; or one thousand (1,000) square feet, whichever is less.” In R-1 districts, RC-1, and A-1 they need administrative approval from the Planning Manager; in PD districts that approval also requires a lot of at least 5,000 square feet and 50 feet wide. An existing structure converted to an ADU may be no larger than 1,000 square feet. There is also one off-street parking space required, which may not sit in a required buffer or setback or to the rear of the unit, an architectural compatibility standard with elevations reviewed before permits, and per-district impervious coverage caps ranging from 30% to 65%.
Unincorporated Osceola County: It Is Not Called an ADU
If you search Osceola's code for “accessory dwelling unit” you will come up empty. Its term, at Sec. 3.6.1(A) of the Land Development Code, is Accessory Living Unit (ALU), grouped with “Guest Home.” That matters when you call the county or search the code yourself.
Osceola takes a different angle on the homestead question than Orange does. Orange makes homestead a condition of permitting the unit at all. Osceola makes it a condition of renting it: ALUs “are permitted to be rented out only if the primary structure has a homestead exemption and, in this instance, shall only be rented out for long-term (not intended for short-term rentals) time periods.” You may build one either way; whether you can put a paying tenant in it is the part that turns on homestead.
Size is the lesser of two numbers, per Table 3.6.1a. On a lot under one acre, the ALU's air-conditioned area may not exceed 60% of the primary structure's air-conditioned footage or 1,000 square feet, whichever is smaller. On a lot of one acre or more the 60% still applies but the square-foot cap drops away. Unlike Seminole, that cap is not absolute — the table is expressly subject to a variance approved by the Board of Adjustment.
Two more things to plan for. Only one ALU or guest home is permitted per conforming lot, and the application is heavier than most: architectural drawings, photographs showing the complete front façade of the existing home, and a property survey by a Florida registered land surveyor showing lot area and all existing and proposed structures. One piece of good news is that ALUs meeting the code's standards are not counted toward density, so the unit does not eat into what the parcel is allowed.
Unincorporated Lake County: The Most Room, and a Recorded Restriction
Lake County (Appendix E, LDR Ch. X, Sec. 10.01.03) is the most generous of the five on size and the most demanding on paperwork. Its ADU may not exceed 1,200 square feet or 70% of the principal dwelling's air-conditioned enclosed living area, “whichever is greater.” Read that operator twice — it is the opposite of Osceola's, and it means a large principal home in Lake can support a genuinely large ADU.
The tradeoff is at the permit counter. The lot “shall be occupied by the owner of the premises,” who may live in either unit — and before the building permit issues, the owner must execute a legal document, recorded in Lake County's public records at the owner's expense, requiring the two dwellings to remain in the same ownership and limiting occupancy of one of them to the owner. Proof of recording is required before the occupancy permit. This is a title-level encumbrance on your property, not a form, and it is the single biggest practical difference between building in Lake and building next door.
Lake also publishes the clearest test for when extra living space legally becomes an ADU: a separate utility meter, a separate address, a connection to the main house by a breezeway or walkway “regardless of whether it is enclosed or open,” or qualifying as a separate dwelling under the Florida Building Code. Homeowners routinely assume a breezeway keeps an addition from counting. In Lake, it does the opposite.
One number worth designing around: impact fees are payable unless the unit qualifies for an exemption, and Lake's deferral at Sec. 22-11 of the County Code applies only to educational impact fees and only where the ADU is 800 square feet or less. The deferral runs until the property is sold or conveyed and is secured by a 30-year mortgage to Lake County recorded against the property. So Lake will let you build an ADU far larger than 800 square feet — it just will not defer the school impact fees on it.
The HOA Gate Nobody Plans For
Zoning approval is not the last word. Seminole County's code says outright that its ADU provisions “do not authorize persons to violate applicable restrictive covenants or homeowner association rules and regulations,” that the County “does not police or enforce” them, and that owners are “solely responsible for compliance.” Across Central Florida's newer subdivisions that architectural-review approval is frequently the real constraint, and it sits ahead of the permit rather than being covered by it. Check your covenants before you check your zoning — it is the cheaper of the two disappointments.
What They Cost to Build
Rules aside, an ADU is a complete small house — its own kitchen rough-in, its own bathroom, its own HVAC — and it prices like one. In this market a full ADU runs $275–$475 per square foot, the same tier as an in-law suite and the most expensive per-foot category we build. Converting existing space is the budget path, because it avoids a new foundation and roof. Plan 16–32 weeks of construction for a detached unit plus the design-and-permitting runway in front of it. Our cost calculator gives you the tier in seconds, and the Orlando home addition cost guide breaks the numbers down.
Where to Start
Confirm the jurisdiction first. Look up whether your parcel is inside city limits or in the unincorporated county — that single fact decides whether a rental ADU is even on the table. Then confirm your zoning district and your lot dimensions, because in Seminole those are not appealable and in Orlando they set your size cap. Only then is it worth drawing anything.
This is general information for the Orlando metro, not legal or zoning advice for your parcel. Rules change, and the other municipalities in our service area — Winter Garden, Ocoee, Apopka, Kissimmee, Clermont, Sanford — each set their own, and an incorporated city's rules replace the county rules above rather than adding to them. The five sets of rules here are the unincorporated counties plus the City of Orlando. Verify with your jurisdiction before committing to a design.
Not Sure Which Jurisdiction You're In?
Call (407) 634-4099 for a free phone consultation. We will tell you which rules apply to your parcel and whether the ADU you have in mind is buildable there before you spend anything on drawings.
Frequently Asked Questions
Can I build an ADU in Central Florida?
In much of it, yes — but the rules are set locally, not by the state, and they differ sharply between neighboring jurisdictions. The City of Orlando and unincorporated Orange, Seminole, Osceola and Lake counties all allow them in single-family areas, and each attaches different conditions — and Osceola does not even use the term, calling them accessory living units. The first question to answer is not "does Florida allow this" but "which jurisdiction is my parcel actually in" — an Orlando mailing address is often unincorporated Orange County, whose rules are considerably stricter than the City's.
Does Florida require cities to allow ADUs by right?
No. Section 163.31771, Florida Statutes, is permissive: a local government "may adopt an ordinance to allow accessory dwelling units in any area zoned for single-family residential use." It sets no deadline, does not override local zoning, and does not stop a county from requiring the owner to live on site. Bills that would mandate ADUs by right have been filed in recent sessions, but a filed bill is not law — and you should not plan a project around one.
Can I rent out an ADU in Orange County?
Only if you live on the property. Orange County's ADU permit page states that ADUs "may only be permitted on properties that qualify as homestead property," that they are "not permitted on non-homestead properties," and that "the property owner must occupy either the primary dwelling or the ADU at all times." You can have a tenant in the other unit — what you cannot do is own the parcel as a pure investment and rent out both.
Which Central Florida jurisdiction is friendliest to a rental ADU?
Of the five verified here, the City of Orlando. Its ADU page says the same person or entity must own both the main house and the ADU, but that "either unit may be owner-occupied or rented long-term" — there is no requirement that you live there. Unincorporated Orange, Seminole, and Lake counties all require the owner to occupy one of the two units, and Lake records that restriction against your title before the permit issues. Osceola does not frame it as an occupancy rule, but it only lets you rent an accessory living unit out if the primary structure carries a homestead exemption.
How big can an ADU be in Lake County versus Osceola County?
They are close to opposites, because the two codes use the same shape of rule with the opposite operator. Lake County caps an ADU at 1,200 square feet or 70% of the principal dwelling's air-conditioned living area, "whichever is greater" — the most permissive size rule of the five. Osceola caps an accessory living unit at the lesser of 60% of the primary structure's air-conditioned footage or 1,000 square feet on a lot under one acre; at one acre or more the 60% still applies but the square-foot cap drops away. Misreading "greater" as "lesser" is the easiest mistake to make with these two.
Do I have to record anything against my property to build an ADU?
In unincorporated Lake County, yes. Before the building permit is issued, the owner must execute — and the County records, at the owner's expense — a legal document requiring the principal dwelling and the ADU to remain in the same ownership and limiting occupancy of one of them to the owner. Proof of recording is required before the occupancy permit. That is a title-level encumbrance, not a form. Seminole requires deed restrictions too, but only where you are claiming the affordable-rental impact-fee reduction.
Are there impact fees on an ADU in Central Florida?
Generally yes, with local relief. Seminole County waives or reduces them if the unit is an affordable rental and the permit application includes an affidavit attesting to that, backed by deed restrictions. Lake County charges them unless the unit qualifies for an exemption, and its deferral covers educational impact fees only, for ADUs of 800 square feet or less, deferred until the property is sold and secured by a 30-year mortgage recorded to the County. Ask about impact fees before you finalize square footage — in Lake in particular, the 800 sq ft line can be worth designing around.
How big can an ADU be in Seminole County?
It depends on the zoning district, and the two commonly-quoted numbers are not interchangeable. In the A-3, A-5, and A-10 districts, ADUs are permitted by right and total floor area "shall not exceed thirty-five (35) percent of the gross floor area of the main residence; or one thousand (1,000) square feet, whichever is less." In R-1 districts, RC-1, and A-1, an ADU needs administrative approval from the Planning Manager; in PD districts it also needs a lot of at least 5,000 square feet and 50 feet wide. An existing structure converted to an ADU may be no larger than 1,000 square feet.
Can I get a variance if my lot is too small for an ADU?
Not in unincorporated Seminole County. Its code is explicit that "the Board of Adjustment shall not consider variances related to ADU size, or minimum area and width of any lot where an ADU is proposed." If the lot does not meet the threshold, there is no appeal path — which makes confirming your lot dimensions the very first step, before any design spend.
Will my HOA stop me from building an ADU?
It can, and the county will not help you. Seminole County's code states plainly that its ADU provisions "do not authorize persons to violate applicable restrictive covenants or homeowner association rules," that the County "does not police or enforce" them, and that owners are "solely responsible for compliance." In much of Central Florida's newer housing stock that architectural-review approval is the real gate, and it sits in front of the permit rather than being satisfied by it.