Do I Need a Permit to Build an ADU in Miami, FL?

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Conditions

Full permit conditions

All 9 conditions for Miami adu permits.

Miami does not present ADUs as a simple citywide by-right permit type. In practice, the project must first fit the property's Miami 21 transect-zone rules and allowed-use framework, then move through the City's building-permit process as habitable residential construction.
Use the City of Miami GIS zoning tool first. Miami 21 treats parcel zoning, allowed uses, density/intensity, parking, and setbacks as address-specific questions rather than a single universal ADU rule sheet.
A detached backyard unit, garage conversion, or internal accessory apartment that functions as a second dwelling will require a building permit through the City's digital permitting system; this is not comparable to a permit-exempt shed.
Miami's setback, height, and lot-coverage rules depend on the property's Miami 21 transect zone. The City's zoning FAQ points applicants to Miami 21 Article 4 Tables 2–4 and the GIS tool for those parcel-level standards.
Parking requirements in Miami are zoning-dependent. The City directs applicants to Miami 21 Article 4 Table 4 for new development parking obligations rather than promising a blanket ADU parking waiver.
Miami-Dade is in the High Velocity Hurricane Zone (HVHZ). New detached ADU construction or major exterior additions must be designed for South Florida wind loads and product-approval requirements, which is a major cost driver compared with non-HVHZ markets.
Because an ADU is habitable space, separate trade permits and inspections are required for electrical, plumbing, mechanical, and utility work. Utility-connection details are project-specific and reviewed during permitting.
Properties in historic districts or on designated historic sites can trigger additional review through the City's historic-preservation process before construction starts.
Florida's 2024 HB 1339 ADU bill is relevant policy context, but local Miami zoning and permitting still control the real permit path for a City of Miami parcel.

Fees

Estimated city fees

Baseline for a simple permitted adu: $2,500–$10,000+ is a realistic Miami planning range for a compliant ADU once zoning, building review, trade permits, and HVHZ-related design costs are included

Fee	Amount	Notes
Upfront building-permit intake / review fees	$500–$2,500+ (estimated range)	Miami states that an upfront fee may apply before documents and drawings are fully submitted. Final pricing depends on valuation and the departments reviewing the project.
Residential building permit + plan review	$2,000–$9,000+ (estimated range)	A habitable detached ADU or substantial conversion is reviewed as real residential construction, not as a minor accessory structure. HVHZ structural review increases soft costs.
Trade permits (electrical, plumbing, mechanical)	$250–$1,500+ each depending on scope	Each trade requires separate permit handling and inspections through the City's digital permitting system.
Historic, county-agency, or utility-related review	Varies by parcel and scope	Historic review, Miami-Dade external agency coordination, impact fees, or utility upgrades can materially increase carrying cost.

Documents

Required documents

City of Miami building permit application through iBuild, with the project routed through the correct digital permitting workflow.
Scaled site plan showing lot lines, principal residence, proposed ADU location, setbacks, easements, and enough detail to confirm Miami 21 zoning compliance.
Architectural floor plans and elevations for the new or converted habitable unit.
Structural plans signed and sealed as required for Florida residential construction, including HVHZ wind-load and anchorage details for detached or heavily altered structures.
Mechanical, electrical, plumbing, and utility plans for the habitable dwelling unit.
Miami 21 zoning support materials demonstrating the parcel's transect zone, applicable development standards, and any parking analysis required by Article 4 Table 4.
Historic-preservation approvals if the parcel is historically designated or located in a regulated district.
County-agency forms or approvals if the project also triggers Miami-Dade external review through DERM, WAS-D, or impact-fee processing.

Timeline

Typical timing

Plan review: 14 business days for a straightforward building review; around 35 business days when the project functions like a special permit or needs broader planning/zoning handling
Total cycle: 4–9 months for many Miami ADU projects from zoning confirmation through final inspection

Miami itself warns that first review cycles are roughly 14 business days for building permits and about 35 business days for special permits. HVHZ engineering, historic review, and county-agency coordination stretch the schedule.

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Process

How the permit process works

Interrogate the parcel in Miami 21 first Use the City GIS zoning tool to identify the transect zone, historic overlays, and parcel conditions. Miami's ADU answer is address-specific, not one-size-fits-all.
Confirm the use and site-development path Check whether the proposed accessory dwelling arrangement is allowed by right, needs a waiver, or triggers another zoning action under Miami 21. Do not assume a backyard unit is automatically allowed just because the lot is residential.
Design for HVHZ and habitability Prepare a real residential plan set. In Miami, new ADU construction must satisfy South Florida wind design, product approval, and life-safety standards that meaningfully affect cost and detailing.
Submit through iBuild / ePlan Create the building-permit application in iBuild, pay any required upfront fees, and upload plans and documents through the City's digital permitting workflow.
Resolve zoning and plan-review comments Expect coordination across building, planning, zoning, and trades. Miami's permit guide notes that special-permit applications can take materially longer than basic building reviews.
Pull trade permits and record any required notices Once the permit is approved, pay final fees, handle required county coordination, and record a Notice of Commencement when applicable before work starts.
Build, inspect, and close out Schedule in-progress and final inspections through the City's digital systems. Keep the full permit paper trail because unpermitted second-dwelling work is costly to unwind in South Florida.

Code basis

What Miami reviews against

City of Miami Miami 21 zoning framework as surfaced through the City's Miami 21 code portal, zoning FAQ guidance, GIS zoning tool, and permit guide; City of Miami digital permitting procedures; Florida residential building-permit requirements with Miami-Dade HVHZ structural context.

Residential permit page Miami permit portal

If you skip the permit

What can go wrong

Miami can stop work and force after-the-fact permitting if you create habitable accessory dwelling space without approval.
If the parcel's Miami 21 zoning does not support the use or site layout, the project can fail after you already spent on design.
Skipping HVHZ engineering or product-approval discipline in Miami-Dade is a structural-risk mistake, not a paperwork detail.
Unpermitted electrical, plumbing, or sewer work on a second dwelling unit creates safety, insurability, and resale problems quickly.
Historic-district work without the required approvals can trigger separate enforcement and redesign obligations.
South Florida buyers, insurers, and lenders care about clean permit history; an unapproved ADU is expensive to legalize later.

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