Free written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
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AfterFast, Reliable Home Additions & ADU Across Miami
A home addition or ADU in Miami runs $53,100 to $153,400 on average, with detached ADUs starting around $106,200 and garage conversions landing between $35,400 and $94,400. Those are real numbers for this market, not national averages. Every Miami job we take lives inside the High-Velocity Hurricane Zone, which means the way we frame, anchor, flash, and finish is different from anywhere else in Florida. Call (877) 610-1318 and we’ll walk your property with you, line by line, before a single number is quoted.
Why Barrett & Sons Construction Is Miami’s Preferred Home Additions & ADU Company
Tom Barrett puts his name on the truck. He’s been running crews since 1998, and his sons are on most Miami job sites with their teams. When you call, a live person answers. When you ask for a price, you get it in writing. When the scope changes, you get a change order in writing before we touch anything. That’s not marketing language. That’s how we’ve kept Miami homeowners from getting burned twice.
Our Home Additions & ADU work across Miami-Dade carries the same 90-Day Done Right Promise that’s written on every contract we sign. If something isn’t done right, one call brings Tom back. He lives twenty minutes from most Miami neighborhoods. If there’s a problem, he wants to know about it faster than you do.
Miami presents a particular set of challenges: CBS block construction, HVHZ wind-load codes, salt air, and a water table that sits close enough to kiss your slab. We’ve opened enough walls in Allapattah, Brownsville, Gladeview, and West Little River to know exactly what’s hiding behind the stucco. That local knowledge is why homeowners push our name across the fence line and why our reputation in Miami is built on inspection sign-offs, not Instagram photos.
Our Home Additions & ADU Services in Miami
We handle the full range of room additions and ADU work in Miami, from permitting through final inspection. Here’s how we approach the four services Miami homeowners ask about most.
ADU Design & Permitting
Before we draft anything, we pull the Miami-Dade product approval lists and check your lot’s zoning envelope and flood zone. In Miami, an ADU that isn’t permitted and NOA-compliant can become an uninsurable liability the day after you finish it. We design to HVHZ uplift loads from the first page, and we file the permit with the county. You never chase paperwork. The permit inspector works for you, not for me, which is exactly why we want him on site before drywall goes up.
Garage Conversion ADU
Converting a detached garage in Miami means working with what’s already there: typically a CBS shell that was built as a garage, not a dwelling. That means adding insulation, upgrading electrical from a single branch circuit to a real subpanel, cutting new window openings through block, and often lifting or redoing the slab to meet finished-floor elevation. When the garage sits in a flood-prone western ZIP code, the slab work gets more involved. We’ll tell you on the first walk whether your garage is a clean conversion or a teardown with extra steps.
New Detached ADU
A new detached ADU in Miami is effectively a small house built to the same code as a big one. Foundation design matters more here than in most markets because Miami limestone and the high water table don’t forgive mistakes. We use shallow foundation systems or pilings where the soils call for them, and we build with NOA-rated products end to end. You’re not getting a prefab shed on blocks. You’re getting a structure that will still be standing after a Category 4 makes landfall closer than anyone wants to think about.
Junior ADU & Interior Conversion
A junior ADU converts existing interior square footage into an independent living space with its own entrance, kitchenette, and bath. In Miami’s 1950s and 1960s CBS homes, this usually means opening interior block walls and working around cast-iron plumbing that’s been there since Eisenhower was in office. We inspect first, then price. If we find corroded drain lines or wiring that won’t carry the load, you’ll see it in writing before we ask for another dollar.
What happens when you call
- 1
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.
Trusted Brands We Service in Miami
We build with materials you can look up, from Techo-Bloc pavers on ADU entries and walkways to Cambridge Pavers on patios and Oldcastle retaining systems where grade changes need holding. When a Miami job calls for Quikrete products for footings, anchors, or slab work, we spec what the structural drawings require rather than whatever is left in the van. Sourcing from established manufacturers matters more in Miami than most places because HVHZ wind load ratings are tied to specific tested assemblies, not generic substitutions. If the inspector asks for the NOA number, we hand it to him.
Common Home Additions & ADU Problems We See in Miami Homes
- CBS block surprises behind the stucco. Miami’s housing stock is overwhelmingly concrete block, not wood frame. Cutting a new opening without an engineer’s load path review can crack walls and compromise roof ties. We bring the engineer before we bring the saw.
- Old flat roofs hiding rotted sheathing. Much of Miami’s 1950s and 1960s housing has built-up flat roofs that are decades overdue. Opening one for a second-story addition regularly reveals failed waterproofing and soft substrate. We pre-inspect so the quote reflects what’s actually up there.
- Salt-air corrosion on anchors and hardware. Coastal air in Miami eats standard fasteners. We use stainless or hot-dipped galvanized hardware as a baseline on structural work, not as an upsell. It’s code-expected, and it’s the only thing that lasts.
- Shallow water table flooding excavations. There are no basements in Miami because the aquifer is right below your feet. Contractors who don’t plan for dewatering flooded holes end up pouring slabs that crack. We plan for the water before we break ground.
Pricing for Home Additions & ADU in Miami, FL
Here’s what Miami homeowners should expect to pay for the core services on this page. These ranges reflect actual build scopes in this market, with HVHZ product requirements and CBS construction realities baked in.
| Service | Typical Miami Price Range |
|---|---|
| Home Addition | $53,100 - $153,400 |
| ADU Construction | $106,200 - $259,600 |
| Garage Conversion | $35,400 - $94,400 |
What moves the number on a Miami home addition? The condition of what’s already behind the walls, the structural upgrades HVHZ triggers, the foundation system your soils demand, and the finishes you choose. Allowances are written into every contract, and every change arrives as a written change order before work proceeds. An allowance that isn’t on paper is a surprise waiting for a date. Call (877) 610-1318 for a free estimate on your specific property.
We Also Serve Cities Near Miami
Barrett & Sons Construction runs crews from our South Florida office into Allapattah, Brownsville, Gladeview, and West Little River, keeping the same permits-pulled, inspections-signed standard across every Miami-Dade ZIP we cover. If you’re in one of these neighborhoods and planning a room addition or ADU, you’ll get the same written pricing and the same face on the job site.
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.
FAQs - Home Additions & ADU in Miami
Miami-Dade County sits inside the High-Velocity Hurricane Zone, the strictest wind-load code in the continental United States. Your addition must use Miami-Dade NOA-approved products and meet HVHZ uplift standards that don’t apply in Broward or Palm Beach. What passes inspection in Fort Lauderdale won’t pass in Miami. Call (877) 610-1318 and we’ll explain exactly which upgrades your specific project triggers before you sign anything.
Sometimes, but not always. A Flagami garage built in the 1960s often sits below the flood elevation FEMA now requires for habitable space. If we have to lift the slab, that’s a line item in writing before it happens. If the soil and elevation work in your favor, we’ll tell you that too. Call (877) 610-1318 for a property-specific answer.
Because the roof is where decades of Miami’s rain and sun have done their work. Before we frame a second story over a 1960s built-up flat roof, we open it and inspect the sheathing and substrate. In Flagami and Little Havana, we routinely find rotted decking from failed waterproofing. You learn about it at the inspection stage, not after we’ve framed on top of it. Call (877) 610-1318 to schedule a pre-construction inspection.
By designing for the water table from day one. In western Miami ZIP codes, the aquifer can sit less than two feet below grade, and there are no basements in Miami for exactly that reason. We use shallow foundation systems or pilings where the soil demands it, and we handle dewatering during excavation. Contractors who ignore Miami’s hydrology pour slabs that fail. We don’t. Call (877) 610-1318 with your address and we’ll tell you what your lot is dealing with.
It means when we open a wall on your 1960s CBS home in Miami and find corroded anchors or undersized rebar, you get a written change order with the exact scope and price before we touch anything. You approve it in writing or we don’t do the work. No surprise invoices at the end. Every allowance is in your contract from the start, and every adjustment follows the same paper trail. That’s the Barrett & Sons standard on every Miami job. Call (877) 610-1318 and ask Tom to walk you through a sample contract.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving Miami and South Florida since 1998.