How Much Does a New Detached ADU Cost in Kendall, FL?
A new detached ADU in Kendall typically runs $90,000-$220,000 and takes 4-7 months from permit to final inspection, depending on whether you choose prefab delivery or stick-built construction. Call (844) 665-0162 and we’ll walk your property, check your setbacks against Miami-Dade’s ADU ordinance, and give you a written estimate with real numbers.
We built our first Kendall ADU in 2019, a 520-square-foot studio behind a pre-Andrew home near SW 117th Avenue. The homeowner had inherited the property from her parents, and the original 1978 concrete-block house sat on a slab with no room to expand. What she didn’t know, and what we discovered during our first site visit, was that the 1992 hurricane repairs had left the main roof’s tie-down hardware non-compliant with current HVHZ standards. That hidden condition didn’t change her ADU project, but it changed how we sequenced the work. We pulled the ADU permit first, then addressed the main house roof as a separate phase so her insurance wouldn’t flag an open permit on the primary structure. This is the kind of sequencing decision that comes up regularly in Kendall’s older neighborhoods, where housing stock from the 1970s and 1980s carries invisible baggage from three decades of Florida weather and patchwork repairs.
At Groundwork Construction Co., we handle new detached ADU projects as part of a full Home Additions & ADU in Kendall program, but this page focuses specifically on the standalone structure. Whether you’re housing family, generating rental income, or adding a home office with real separation from the main residence, a detached unit in Kendall faces constraints that don’t apply to garage conversions or attached additions. Setbacks, utility trenching through limestone, and HVHZ product approvals all shape what gets built and how much it costs.
How We Build a New Detached ADU in Kendall - Start to Finish
Every new detached ADU follows five stages. Here’s what happens, how long each takes, and what you’ll need to decide.
Stage 1: Site survey and feasibility (1-2 weeks). We measure your lot, verify setbacks against Miami-Dade’s unincorporated zoning for your specific parcel, and run a utility locate. In western Kendall, we also probe for rock depth. You’ll decide: exact ADU size and whether to connect to the main house’s sewer line or install a separate septic system. If your lot sits on the Miami Limestone formation with rock at 8 inches, trenching costs jump significantly, and we’ll flag that now.
Stage 2: Design and permitting (6-10 weeks). We produce construction drawings stamped by a Florida-licensed engineer, then submit to Miami-Dade’s Building Department. Every structural component, roofing product, window, and exterior door must carry a current Miami-Dade NOA for HVHZ use. We maintain standing relationships with HVHZ-approved suppliers because inspectors reject unlisted products on the spot. You’ll decide: prefab shell versus stick-built, exterior finish materials, and window/door package. We work with prefab partners including Mighty Buildings and Boxabl for faster timelines, or we can design and build from scratch.
Stage 3: Site prep and foundation (2-3 weeks). We clear the build area, trench for utilities, and pour the foundation. In Kendall’s limestone zones, this often means bringing in a rock hammer or hydro-vac equipment. You’ll decide: slab-on-grade versus elevated stem wall, based on your flood zone designation and finished floor height preferences.
Stage 4: Structure and enclosure (4-8 weeks). For prefab units, this means crane delivery and set on the prepared foundation. For stick-built, we frame, roof, and install HVHZ-rated windows and doors from our roster of approved manufacturers. You’ll decide: interior layout finalization, electrical fixture locations, and any plumbing upgrades if you’re adding a full kitchen.
Stage 5: Interior finish and final inspection (3-4 weeks). We install flooring, cabinetry, countertops, fixtures, and appliances, then coordinate Miami-Dade’s final inspection. You’ll decide: paint colors, hardware, and whether to add Backsplash, Tile & Flooring in Kendall upgrades beyond the base spec. Many homeowners also ask us to coordinate Kitchen Design & Layout in Kendall for the ADU’s cooking space, especially for rental units where tenant appeal matters.
Our Home Additions & ADU crew manages all five stages. You don’t juggle separate contractors for framing, roofing, electrical, and finish work.
The Build Options You’ll Actually Choose Between
Every new detached ADU in Kendall forces real trade-offs. Here’s what we walk homeowners through:
- Prefab shell (Mighty Buildings, Boxabl, Plant Prefab, or Tuff Shed base structures): Faster timeline, factory-controlled quality, and often lower per-square-foot cost. The trade-off: less customization, and you’ll still need local foundation work, utility connections, and Miami-Dade’s NOA verification for any site-installed components. Best for homeowners who want a fast, predictable build and don’t need exotic layouts.
- Stick-built on site: Full design flexibility, easier to match your main house’s architectural character, and simpler to accommodate odd lot shapes or setback constraints. The trade-off: longer timeline, more weather exposure during Kendall’s wet season, and higher labor cost. Best for heritage neighborhoods or when the ADU must visually integrate with a 1980s concrete-block home.
- Utility connection strategy: Tapping the main house’s sewer and water lines avoids separate meter fees but requires trenching that may hit limestone. Separate utilities add $4,000-$8,000 but give rental-meter flexibility. You’ll decide based on your intended use and the physical path between structures.
- Impact-rated versus standard windows and doors: In Miami-Dade’s HVHZ, you need impact-rated products anyway for any new construction. The choice is really between mid-tier vinyl-impact combinations and premium aluminum or fiberglass architectural lines. The price spread is roughly $3,000-$7,000 for a typical 500-square-foot ADU.
- Kitchen scope: Wet bar with mini-fridge and microwave, or full cooking kitchen with range and dishwasher? This single decision can swing your finish budget by $8,000-$15,000 and determines whether you need a grease trap or can use standard plumbing.
What New Detached ADU Costs in Kendall, FL
| Component | Typical Range |
|---|---|
| Base ADU construction (stick-built, 400-600 sq ft) | $90,000-$150,000 |
| Premium finishes + full kitchen | $140,000-$220,000 |
| Prefab shell + local foundation/site work | $75,000-$130,000 |
| Rock excavation (western Kendall lots) | $3,000-$8,000 additional |
| Separate utility meter installation | $4,000-$8,000 additional |
Five variables push your number up or down. First, size: every 100 square feet adds roughly $15,000-$25,000 in Kendall’s current market. Second, rock conditions on your specific parcel, which we can’t predict without probing. Third, kitchen and bathroom scope - a wet bar and half-bath versus full cooking and bathing facilities. Fourth, exterior finish matching: stucco to blend with your main house costs more than basic siding. Fifth, prefab versus stick-built, with prefab generally 15-25% faster but not always cheaper once foundation and site work are included.
A written estimate from Groundwork includes all permits, HVHZ-compliant materials, labor, and final inspection coordination. It does not include your appliance package, window treatments, or landscaping restoration beyond basic grade and seed. We’ll tell you exactly what’s in and what’s out before you sign.
What Kendall Homes Specifically Do to This Job
Kendall’s housing stock shapes every new detached ADU we build here. The 1970s-early 1990s concrete-block homes that dominate neighborhoods from Kendale Lakes to the Hammocks weren’t designed with accessory structures in mind. Setbacks in unincorporated Miami-Dade often leave less room than homeowners expect, especially on 7,500-square-foot lots common in pre-1990 subdivisions.
The HVHZ permitting reality is non-negotiable. Pulling a construction permit in unincorporated Kendall means every structural component and roofing product must have an active Miami-Dade NOA number on file. Inspectors here will reject unlisted products on the spot. Local crews maintain standing relationships with HVHZ-approved suppliers rather than sourcing from big-box stores the way contractors in Orlando or Tampa routinely do. This isn’t bureaucracy for its own sake - Hurricane Andrew proved what happens when wind-borne debris meets substandard construction, and Kendall was ground-zero for that 1992 landfall.
We also see the legacy of hasty post-Andrew repairs. Pre-1993 homes that survived often carry mixed-quality roofing assemblies and non-compliant tie-down hardware that was never fully brought to current code. When we build your ADU, we don’t touch your main house structure, but we do coordinate our work so your existing roof condition doesn’t create insurance or inspection conflicts. The June-October wet season adds scheduling pressure too - outdoor concrete pours and roofing work need tight windows between afternoon thunderstorms, and experienced Kendall crews price that contingency into their bids.
We cover Kendall and surrounding communities including Pinecrest, Glenvar Heights, South Miami, and Cutler with the same HVHZ-compliant approach.
Serving Kendall, FL - Our Local Coverage Area
We’re based in the Kendall area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
Frequently Asked - New Detached ADU in Kendall
From permit submission to final inspection, expect 4-7 months. Prefab units on simple lots can hit the shorter end; stick-built projects with rock excavation or complex utility work run longer. Miami-Dade’s permit review typically takes 6-10 weeks for ADUs, which we build into our schedule. Call (844) 665-0162 and we’ll give you a realistic timeline for your specific lot.
Yes, absolutely. Unincorporated Kendall falls under Miami-Dade County building jurisdiction, and every new detached ADU requires a full building permit with structural, electrical, plumbing, and mechanical inspections. The structure must also meet current Florida Building Code and HVHZ wind-load requirements. We handle the entire permit process as part of our standard scope.
Often yes, but it depends on your main service capacity and the ADU’s demand. A studio with a mini-split and tankless water heater usually taps existing lines without issue. A two-bedroom with full electric range, dryer, and central AC may require a service upgrade. We assess this during our initial site survey and include any necessary electrical work in our estimate.
A Tuff Shed-style utility structure converted to basic living space with minimal kitchen and bath runs toward the lower end of our range, typically $75,000-$95,000 all-in. The trade-off is limited insulation, basic finishes, and no ability to match your main house’s architecture. For rental income or long-term family use, we generally recommend investing in proper construction that won’t cost more to retrofit later.
Groundwork provides a workmanship warranty on all construction, and every product we install carries its manufacturer’s warranty - from roofing materials to windows to appliances you select. Because we work with 50+ recognized brands across every category, you’re not locked into a single vendor’s warranty terms. We document all warranty registrations and pass the paperwork to you at final walkthrough.
Ready to Talk Through Your Kendall ADU?
Call (844) 665-0162 for a free on-site estimate. Raymond Estevez or a senior project manager will walk your property, check setbacks and rock conditions, explain your prefab versus stick-built options, and deliver a written estimate with real numbers within 48 hours. No deposit required to start the conversation.
Written by Raymond Estevez, Owner at Groundwork Construction Co., serving Kendall and South Florida.