Free written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
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AfterTrusted Home Additions & ADU for Miami Homeowners
Most Miami homeowners who call us bought their place between 2015 and 2022, paid more than they expected, and now need space that matches what they paid for. A growing family, aging parents moving in, or a home office that does not double as a laundry room - these are the reasons we build Home Additions & ADU - Miami across the area, from Coral Gables to Miami Shores. We’ve delivered over 4,000 projects since 2007, every one with a written price before work started and a documented photo record when the crew left. Call (786) 321-4970 to schedule your free estimate.
What Our Home Additions & ADU Service Includes
ADU Design & Permitting
An accessory dwelling unit, or ADU, is a self-contained living space on the same lot as an existing home - it needs its own kitchen, bathroom, sleeping area, and a separate entrance. In Miami, the design and permitting phase is where most projects stall: Miami-Dade County has specific setback requirements, parking provisions, and owner-occupancy rules that differ by zoning district. We prepare architectural drawings, structural plans, and energy calculations in-house, then shepherd the package through Miami-Dade’s Building Department and any relevant homeowners association review. Our permit approval rate on first submission runs above 90% because we verify zoning before we draw a line.
Garage Conversion ADU
A garage conversion ADU transforms an existing garage into a habitable unit, which typically costs less than new construction because the roof and slab are already in place. In Miami, this works best for attached two-car garages with ceiling height above 7 feet 6 inches and a slab that meets current flood-elevation requirements - many homes in Westchester and Olympia Heights were built at grades that need addressing. We assess the existing slab for moisture intrusion, upgrade insulation to meet Florida’s energy code, and run new electrical and plumbing lines so the unit functions independently. Every garage conversion we quote includes a written line-item breakdown for the slab assessment, any flood-ventilation upgrades, and the finished living space.
New Detached ADU
A new detached ADU is a standalone structure, typically 400 to 1,200 square feet, built from foundation to finish on the same lot as the primary residence. In Miami’s coastal neighborhoods like Key Biscayne and Miami Beach, this means designing for wind-borne debris zones, salt-air corrosion on exterior hardware, and floodplain elevation requirements that can add $8,000-$15,000 to foundation costs compared to inland sites. We pour elevated stem-wall or slab-on-grade foundations with proper tie-downs, frame with pressure-treated lumber rated for ground contact, and specify impact-rated windows and doors where the code requires them. The written quote separates foundation, shell, and finish costs so you see where the money goes.
Junior ADU & Interior Conversion
A junior ADU, or JADU, is created within the existing footprint of a single-family home - typically by converting a bedroom or attached storage area into a small independent unit with its own entrance and efficiency kitchen. This works well in Miami’s older neighborhoods like Miami Springs and South Miami, where lot coverage limits make detached construction difficult and the original 1950s-1970s floor plans include generous secondary bedrooms. We add a separate exterior door where possible, install a wet bar or compact kitchen with a 120-volt cooktop, and run a dedicated electrical sub-panel so the unit meters separately if the owner chooses. The key constraint is the JADU must share a bathroom with the main house or add one within the existing walls, which we assess during the first site visit.
ADU Site Prep & Utilities
Site preparation for an ADU in Miami often involves more than clearing grass - many lots in Hialeah and North Miami have fill soil, shallow bedrock, or utility easements that constrain where and how you build. We locate water, sewer, and electrical mains with certified utility locates, then trench new service lines or upgrade existing capacity to handle the additional load. For properties on septic, we evaluate whether the existing drain field can absorb a second dwelling or if a new system is required, which in Miami-Dade typically runs $7,500-$14,000 depending on soil percolation. The site prep quote includes dewatering if we hit the seasonal high water table, which is common in low-lying areas near the Miami River and its tributaries.
Room Additions
A room addition extends the footprint of the existing house - a master suite, family room, or expanded kitchen - and must tie into the existing roofline, foundation, and structural system without creating leaks or settlement cracks. In Miami’s hurricane-prone climate, this means matching or upgrading the existing wind-load connections, installing continuous insulation to prevent thermal bridging, and detailing the junction between old and new to shed water in driving rain. We typically see room addition requests in Coral Gables and Pinecrest, where homeowners want to stay in established neighborhoods rather than absorb the transaction costs of selling and buying. Our process includes a structural assessment of the existing house to confirm it can support the new load, with engineering stamped and delivered as part of the permit package.
Second Story Additions
A second story addition doubles or increases living space vertically, which preserves yard space but places significant new load on the existing foundation and walls. In Miami, this is common in neighborhoods like Miami Shores and North Miami, where original 1,200-square-foot ranch homes sit on generous lots. We start with a geotechnical evaluation of the existing foundation - many post-war slabs were poured without footings adequate for a second floor - and specify either underpinning or a new pier-and-beam system if needed. The structural package includes Miami-Dade’s required continuous load path from roof to foundation, with hurricane straps and hold-downs documented in the photo record at every stage.
Sunrooms & Enclosed Patios
A sunroom or enclosed patio converts an open outdoor space into conditioned or semi-conditioned living area, typically with large glazing areas and a lightweight roof system. In Miami, the critical detail is the thermal envelope - uninsulated glass walls create solar gain that overwhelms standard HVAC systems, so we specify low-E, impact-rated glazing with a solar heat gain coefficient below 0.25 and tie the new space into the home’s central air or install a dedicated mini-split. We build sunrooms with aluminum or vinyl-framed systems from manufacturers who supply Miami-Dade NOA (Notice of Acceptance) documentation, which is required for permit approval. The written quote distinguishes between three-season and four-season construction, with pricing that reflects insulation, HVAC, and flooring differences.
What happens when you call
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A real person answersNo phone trees - you reach a local pro.
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You get an upfront price rangeHonest numbers before anyone is dispatched.
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A background-checked tech heads outLicensed & insured, dispatched right away.
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You approve before work beginsNothing starts until you say go.
Brands We Service for Home Additions & ADU
We’ve installed Toto toilets and lavatories in more than 200 ADU bathrooms across Miami-Dade County, including compact wall-hung models that save space in junior ADUs without sacrificing the brand’s dual-cyclone flush performance. Toto’s Washlet compatibility is a detail we note in the written scope when a client requests it, with the electrical rough-in specified upfront so the bid is complete. We also specify Schluter waterproofing systems for tile showers and wet-area floors in nearly every ADU we build - the Kerdi membrane and prefabricated shower trays reduce installation time and eliminate the variability of traditional hot-mop or vinyl pan construction. Our crews are trained on Schluter’s specified installation sequence, and we document each layer in the photo record before tile covers it.
American Standard and Delta fixtures round out our typical ADU specifications, with American Standard’s Cadet Pro line for budget-conscious rental units and Delta’s Trinsic and Cassidy collections where the owner occupies the space. We maintain trade accounts with all four brands, which means the prices in our written quotes reflect actual material costs rather than retail markup. Whether you have a preferred brand already or want us to recommend based on your budget and use case, the quote lists every fixture by manufacturer and model number so you can compare it against any other estimate line by line. And under our Free Second Opinion offer, bring us a competitor’s written quote and we’ll review it against our numbers at no charge.
BeforeAfterSigns You Need Home Additions & ADU Right Now
- Your household has outgrown the bedrooms you have. In Miami’s market, where median home prices have more than doubled since 2015, moving to a larger house means absorbing six-figure transaction costs plus a higher mortgage rate. A room addition or ADU adds function without the friction of selling, and the cost typically amortizes favorably against Miami’s appreciation trajectory.
- You’re paying for off-site storage that exceeds $200 monthly. A 10-by-15 storage unit in Miami runs $180-$280 per month, which is $21,600-$33,600 over ten years with no equity built. Converting a garage or building a detached unit with storage on the ground floor and living above captures that outflow and adds property value.
- An aging parent needs proximity but not dependence. Miami’s multigenerational household rate is among the highest in the nation, and an ADU provides separate living quarters with the security of family nearby. The alternative - assisted living at $4,500-$7,000 monthly in Miami-Dade - makes the construction cost recoverable in under four years in many cases.
- Your home office is a closet or a corner of the living room. Remote work has stabilized in Miami’s professional sectors, and a dedicated workspace is now a resale consideration, not a luxury. A 120-square-foot office addition or a converted detached ADU qualifies for home-office deductions and separates work from domestic life in a way that improves both.
- The roof over your garage or patio is failing and must be addressed anyway. In Miami’s climate, a leaking flat roof over an attached garage or patio creates structural damage within two to three wet seasons. Rather than re-roofing unused space, converting it to conditioned area while the structure is open captures the repair cost as part of a value-adding project.
Our Home Additions & ADU Process - Step by Step
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Site evaluation and written scope. We visit your property, measure existing conditions, and photograph the structure, utilities, and access points. Within 48 hours, you receive a written scope of work with a flat price, a material specification list, and a projected timeline. Under Clause 1 of The Haven Standard, this price is delivered before any work starts - always.
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Zoning verification and preliminary design. We pull the property’s zoning classification, setback requirements, and flood zone designation from Miami-Dade County records, then prepare preliminary floor plans and elevations. If the site has constraints - an easement, a protected tree, or a homeowners association with design review - we identify them now and adjust the design or budget accordingly, with any changes documented in a revised written quote.
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Permit application and engineering. Our in-house drafters complete construction documents with structural, electrical, and plumbing details, then submit to Miami-Dade Building Department or the relevant municipal authority. We track the review cycle, respond to corrections, and schedule required pre-construction meetings. The permit set and approved plans become part of your project file, delivered at completion.
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Construction with documented progress. A background-checked, uniformed crew arrives on schedule, and every visit generates a dated photo record uploaded to your project portal. We hold weekly site meetings or phone calls to review progress against the written timeline, and no change to scope proceeds without a signed change order - this is the administrative discipline Haven acquired Rowan for, and it is why our projects finish within a few percent of the agreed price.
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Final inspection, walkthrough, and warranty delivery. We schedule all required inspections, correct any deficiencies before the final sign-off, and conduct a walkthrough with you using a punch list we both sign. You receive the final photo record, as-built drawings, manufacturer warranties for all specified materials, and the 365-Day Done Right Promise printed on a terms page you can reference. If anything is not done right, Rowan makes it right.
How Much Does Home Additions & ADU Cost in Miami?
A typical home addition in Miami runs $53,100-$153,400 depending on whether it is a ground-floor room addition, a second-story build, or a full detached ADU with independent utilities. ADU construction specifically ranges from $106,200-$259,600, with garage conversions at the lower end at $35,400-$94,400 because the structural shell exists. These ranges reflect Miami’s labor rates, the cost of impact-rated materials in wind-borne debris zones, and the foundation work required in flood-prone areas.
| Project Type | Typical Range in Miami |
|---|---|
| Room Addition (ground floor, 400-600 sq ft) | $53,100-$94,400 |
| Second Story Addition (800-1,200 sq ft) | $106,200-$153,400 |
| Garage Conversion ADU | $35,400-$94,400 |
| New Detached ADU (400-800 sq ft) | $106,200-$212,400 |
| Junior ADU / Interior Conversion | $23,600-$70,800 |
| Sunroom / Enclosed Patio (three-season) | $17,700-$47,200 |
| Sunroom / Enclosed Patio (four-season with HVAC) | $35,400-$82,600 |
Several factors move a project within or above these ranges. Foundation conditions are the largest variable - a slab that needs elevation or underpinning can add $15,000-$40,000. Utility upgrades, especially electrical service from 100 to 200 amps or sewer connection fees in Miami-Dade, run $3,500-$12,000. Finish selections matter: quartz countertops from Cambria or Caesarstone, custom cabinetry from KraftMaid or Wellborn, and imported tile all scale the budget predictably, and our quotes itemize these so you can adjust without guessing.
To avoid overpaying, get at least two written quotes with line-item breakdowns you can compare directly. Our Free Second Opinion service exists for this - bring any competitor’s written estimate and we’ll review it clause by clause at no charge. The estimate we deliver is a flat price with a written scope and a written warranty; “call for a quote” is not an option here.
Home Additions & ADU Near Miami - Our Service Area
We build across Miami-Dade County, from Home Additions & ADU in Miami proper through Home Additions & ADU in Brownsville and Home Additions & ADU in Miami Beach, with regular projects in Miami Springs, Key Biscayne, Miami Shores, South Miami, Coral Gables, Westchester, Olympia Heights, Hialeah, and North Miami. Typical lead time from signed contract to permit in hand is 4-6 weeks in Miami-Dade’s current queue, with construction duration ranging from 6 weeks for a garage conversion to 5-7 months for a detached ADU. We coordinate inspection schedules to minimize downtime, and our live-answer phone line means you reach a person, not a voicemail, when you have a question about your project’s status.
Serving Miami, FL - Our Local Coverage Area
We’re based in the Miami 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 Questions - Home Additions & ADU in Miami
A home addition expands the existing house - a new bedroom, expanded kitchen, or second story - while an ADU (accessory dwelling unit) is a separate, self-contained living space on the same lot with its own kitchen, bathroom, and entrance. In Miami, ADUs are governed by specific zoning codes that limit size, location, and sometimes owner occupancy, whereas room additions follow standard residential building codes. Call (786) 321-4970 and we’ll verify which option your property qualifies for during a free site evaluation.
A garage conversion ADU typically takes 6-10 weeks from permit to final inspection, while a new detached ADU runs 4-7 months depending on foundation complexity and Miami-Dade’s inspection availability. Room additions fall in between at 8-14 weeks for ground-floor work, and second-story additions extend to 4-6 months due to structural tie-in requirements. The permit phase adds 4-8 weeks upfront, which we manage in parallel with material procurement to compress the overall timeline.
ADU construction in Miami ranges from $106,200-$259,600 for a new detached unit, with garage conversions at $35,400-$94,400 and junior ADUs at $23,600-$70,800. The per-square-foot cost runs higher than new single-family construction because ADUs require the same systems - kitchen, bath, HVAC, electrical - compressed into a smaller footprint with more complex utility tie-ins. Call (786) 321-4970 for a written estimate specific to your property; estimates are free and include a line-item breakdown.
Yes. We specify and install Toto, American Standard, and Delta plumbing fixtures in the majority of our ADU bathrooms, and we use Schluter waterproofing systems on nearly every tile shower and wet floor we build. Our trade accounts with these brands keep material costs transparent in the written quote, and our crews are trained on manufacturer installation requirements so warranties remain valid. If you have a different preferred brand, we source it through our fifty-plus vetted supplier relationships.
We do not market emergency construction services - ADUs and additions are planned projects with engineered solutions, not urgent repairs. However, if our site evaluation uncovers unexpected structural damage - termite-compromised framing, corroded rebar, or foundation settlement - we document it with photographs, prepare a signed change order with options and pricing, and proceed only with your written authorization. The 365-Day Done Right Promise covers any defect in our workmanship discovered after completion.
Every project is backed by our 365-Day Done Right Promise: if it is not done right, Rowan makes it right, with the guarantee printed on a terms page, not an asterisk. Manufacturer warranties on Toto, American Standard, Delta, Schluter, and other specified products pass through to you at completion. Structural work carries the statutory warranty required by Florida law, and our documented photo record provides the evidence to support any claim.
Gather any existing surveys, permits, or homeowners association covenants for your property, and note any specific requirements - a target move-in date, a preference for certain brands, or a maximum budget. We handle zoning verification, utility locates, and preliminary measurements during our site visit, so you do not need engineering drawings or architectural plans to start. Call (786) 321-4970 to schedule; the estimate is a flat written price with a written scope, delivered before any work starts, always.
Schedule Your Home Additions & ADU Service in Miami Today
Call (786) 321-4970 to schedule your free estimate. You’ll receive a written price with a line-item scope before any work starts, backed by the 365-Day Done Right Promise and the documented photo record that comes standard on every Rowan project. A live person answers calls 24/7, and our Free Second Opinion service means you can bring any competitor’s written quote for a clause-by-clause review at no charge.
Written by Grant Rowan, Owner at Rowan Construction Group, serving Miami since 2007.