Cost to ADU / In-Law Suite Construction in Miami, FL

$64,800–$270,000 in Miami

8% above the national average · 1.08x cost multiplier

Homeowners in Miami typically spend $64,800–$270,000 on a adu / in-law suite construction, about 8% above the national average. Labor rates and contractor availability in the Southeast region drive much of the price difference. Permit requirements and material delivery costs also play a role. See the full tier-by-tier breakdown below before requesting bids.

Cost Breakdown in Miami

Line Item	Low	Mid	High
Cost per sq ft	$162	$270	$432
Materials	$30,240	$70,200	$129,600
Labor	$34,560	$75,600	$118,800
Permits	$4,320	$8,640	$16,200
Design	$5,400	$10,800	$21,600
Total	$74,520+8% vs. national avg	$165,240+8% vs. national avg	$286,200+8% vs. national avg

Budget

Garage conversion ADU (400 sq ft) - kitchen, bathroom, bedroom, electrical upgrade, no exterior changes. Most affordable ADU type.

Mid-Range

Detached backyard ADU (600 sq ft) - new construction on concrete foundation, full kitchen, bathroom, bedroom, separate utilities, standard finishes

Premium

Custom detached ADU (800+ sq ft) with high-end finishes, vaulted ceilings, full kitchen, 1.5 bathrooms, separate utilities and address, premium landscaping

Material Options

Material prices below are national averages; availability in Miami may shift costs slightly.

Material	Cost/Unit	Pros	Cons	Best For
Garage Conversion ADU	$80 - $200 per sq ft	Lowest cost, structure exists, fastest permitting in many states, minimal site work	Requires losing garage parking, typically smallest footprint, attached to main house	Homeowners with detached garages who want the lowest-cost path to rental income or multi-generational livingLowest cost, structure exists, fastest permitting in many states, minimal site work
Basement Conversion ADU	$100 - $225 per sq ft	Uses existing space, natural privacy from main house, lower cost than new construction	Requires egress windows, can feel cave-like without proper light, limited if basement has low ceilings	Homes with full-height unfinished basements in markets where ADUs are in demandUses existing space, natural privacy from main house, lower cost than new construction
Above-Garage Addition ADU	$175 - $325 per sq ft	Separate from main house living area, good privacy, no lot coverage increase	Requires structural assessment of existing garage, staircase required, more complex than conversion	Properties where lot coverage is maxed out or where separation from the main house is a prioritySeparate from main house living area, good privacy, no lot coverage increase
Prefab / Modular ADU	$150 - $300 per sq ft (including site work)	Faster construction, predictable pricing, some high-quality options, off-site quality control	Still requires permits and full site work, delivery and placement costs add up, limited customization	Markets where prefab ADU companies operate and homeowners who want faster construction timelinesFaster construction, predictable pricing, some high-quality options, off-site quality control
Custom Stick-Built Detached ADU	$200 - $400+ per sq ft	Fully customizable, can match main house architecture perfectly, highest long-term value	Most expensive option, longest timeline, most complex permitting	Homeowners who want a long-term investment that looks like a natural part of the propertyFully customizable, can match main house architecture perfectly, highest long-term value

Other Projects in Miami

Full Kitchen Remodel

Full Bathroom Remodel

Roof Replacement (Asphalt Shingles)

Back to national average for ADU / In-Law Suite Construction

Miami Estimate

Typical Range

$64,800–$270,000

vs. National Average

8% above national

Cost Multiplier

1.08x

Cost Per sq ft

$162–$432

Estimates apply Miami's 1.08x regional cost multiplier to national averages. Actual bids vary by contractor, project scope, and timing.

See national average costs →