Home Additions in Miami, FL — Full Room Additions, Second-Story Additions, and Garage Conversions

We build full home additions only — three project types under one Florida CGC license, one team, end to end.

We do build:

• Room additions — single-room or multi-room horizontal additions on a new foundation, tied into the existing exterior wall
• Second-story additions — full or partial second floors over an existing single-story home, including the structural retrofit work
• Garage conversions — attached or detached garage to conditioned living space, full envelope upgrade
• Combined additions — addition scope paired with whole-home renovation when the project warrants both running together

We do not take on:

• Accessory Dwelling Units (ADUs) or detached guest houses (Florida 2024–2025 ADU legislation has jurisdiction-specific rules that warrant a dedicated project setup, not a line-item)
• Pool houses, cabanas, or sheds as standalone scope
• Decks, patios, or pergolas as standalone scope
• Screen enclosures or sunroom kits
• Driveway expansions, fence work, or landscape additions
• Any addition where the homeowner does not own the property or have a clear path to title

The scope gate exists because a home addition is a 4–15 month project depending on type, with engineering, permitting, and inspections that need a single licensed GC running the sequence. Anything smaller is the wrong fit.

Most homeowners come to us when one of five situations applies. The right project depends on which one — and on whether the math actually works on your specific property.

The family outgrew the floor plan. A new child, an aging parent moving in, a long-term remote work arrangement, a teenager who needs their own space — the most common driver. The decision is rarely "how much square footage" — it's whether the addition gets you the right rooms in the right adjacencies. A 200-square-foot primary suite expansion does not solve the same problem as an 800-square-foot second-story buildout with two bedrooms and a bath.

The lot can't hold a horizontal addition. Setbacks, lot coverage limits, zoning floor-area-ratio limits, an existing pool, or mature trees often rule out a single-story addition footprint. When the only buildable direction is up, a second story addition Miami homeowners consider becomes the default option — but the structural retrofit on the existing first floor is the real cost driver.

The garage isn't pulling its weight. A two-car attached garage that holds storage and one car is a strong candidate for a garage conversion Miami project — 400–500 square feet of conditioned space without buying new foundation or framing. The infill of the overhead door opening with a HVHZ-rated wall assembly is the technical work.

You're considering moving but the neighborhood holds you. When the cost-per-square-foot math compares the addition to the cost of moving — agent commissions, closing costs, moving costs, the higher tax basis on a new homestead — the addition often wins, even when the contract price looks high in isolation.

You're already remodeling and the scope is creeping outward. A kitchen remodel that wants to break through an exterior wall, a primary bath that wants to expand into the side yard, a whole-home renovation that needs one more bedroom — these are addition projects wearing remodel clothes. We surface this during scope conversations because adding 200 square feet under a separate addition permit is a different project than calling it "an extension of the kitchen remodel" and trying to push it under a renovation permit.

When the right answer is something else — a full kitchen or bathroom remodel rather than an addition — we tell you. If your scope is really a bathroom remodeling miami project that doesn't expand the footprint, the bathroom tentpole page is the better starting point.

Adding conditioned square footage to an existing home is structurally and procedurally different from remodeling the kitchen or building a new house from dirt up. The new portion has to meet current Florida Building Code 8th Edition requirements, including HVHZ envelope on every new exterior opening in Miami-Dade and most of Broward: impact glazing, NOA-rated assemblies, hurricane strapping, the full envelope spec. The existing portion of the home stays under whichever code cycle it was built to, except where the addition forces it forward.

That last clause is the entire complexity of an addition. The new portion is a code-current new build. The existing portion is grandfathered. The seam between them is where the work is: where the new framing ties into the existing roof, where the new electrical home-run lands at the existing panel, where the new water service ties into the existing supply, where the new slab meets the existing foundation. A contractor who treats an addition as "kitchen remodel plus new walls" gets the seam wrong, and the inspector finds it.

The three addition types we build sit on a spectrum of how much new structure is involved.

The FEMA 50% rule, the single highest-stakes question on a coastal addition.

If your home is in a FEMA Special Flood Hazard Area, and a meaningful portion of single-family stock in Miami-Dade and coastal Broward is, there is a regulation that can change the project entirely. It is called the substantial improvement rule. The rule, in plain language: if the cost of any improvement to the home (an addition counts) exceeds 50% of the home's pre-improvement market value, the entire structure must be brought into compliance with current flood code. That typically means raising the entire finished-floor elevation to current Base Flood Elevation plus the local freeboard requirement, often four to six feet of elevation gain on a slab-on-grade home built to a pre-current flood code.

The math gets ugly fast. A homeowner planning a $400,000 second-story addition on a $500,000 coastal home in a flood zone hits the 50% threshold by a wide margin. Rather than an addition, the project becomes "addition plus raise the existing house plus replace the foundation system." Add $200,000–$400,000 to the scope and turn a 9-month addition into a 14-month near-rebuild. Sometimes the project still pencils. Sometimes the right answer is a smaller addition that stays under the 50% threshold. Sometimes the right answer is to tear down and start over under a clean new-construction permit.

We check this on every addition project in a flood zone before we quote. The answer determines what project you are actually buying.

Most of the homeowners who land here split into four buckets. The right answer depends on which bucket fits.

You need new conditioned square footage. Bedroom, primary suite, home office, in-law suite, expanded living area. This is the core home additions Miami scope, and it's what most of this page covers.

You're combining an addition with kitchen or bath scope. A primary suite addition that includes a new primary bath, or a rear addition that opens up an existing kitchen — both are common. The addition runs as the master scope; the kitchen and bath portions run inside it. If the kitchen scope is the larger project and the addition is the smaller piece, the kitchen remodeling miami tentpole is your better starting point and we'll loop in the addition scope from there.

You need a bathroom but the existing footprint can hold it. Then you don't need a home addition — you need bathroom remodeling contractors miami homeowners trust for full bath scope. Our bathroom tentpole covers the four pricing tiers, fixture and finish detail, and the FAQ depth on lead times.

You're considering full whole-home work. A home addition + whole-home gut renovation is one of the most common multi-service Gaven projects. The structural engineering for the addition gets coordinated with the full-house electrical, plumbing, and HVAC redesign. See our home renovation tentpole for the whole-home scope, and we'll integrate the addition into a single project schedule.

We do not build accessory dwelling units (ADUs), detached guest houses, or pool houses on this scope. ADUs are a separate conversation — Florida's 2024–2025 ADU legislation introduced jurisdiction-specific rules around addressing, utility connections, and owner-occupancy that warrant a dedicated project setup, not a line-item add to a home addition.

Pricing on additions varies more than on kitchens or bathrooms because the cost driver mix is different across the three project types. The honest framing is per square foot of new conditioned space, with type-segmented narrative around it.

$300–$550 per square foot of new conditioned space is the working range for room additions and second-story additions in Miami-Dade and Broward in 2026, with finish level driving most of the variance and HVHZ envelope cost driving the rest. Garage conversions sit lower per square foot because slab and envelope already exist; the cost is concentrated in MEP buildout and code-classification work.

Translated to total project bands, with the understanding that scope and finish level move these meaningfully:

There are dozens of remodeling contractors marketing additions across Miami-Dade and Broward, and another set of high end home remodeling South Florida builders pitching custom additions at the upper price band. The shortlist worth interviewing shares five operational traits.

Verifiable license and permit history. Florida Certified General Contractor — the CGC tier — is the only license class authorized for unlimited residential structural scope including additions. A Certified Residential Contractor (CRC) is limited to two-story scope; a Certified Building Contractor (CBC) to three. Pull any contractor's permit history at BuildZoom before signing. Gaven holds CGC license GCG1524886 with 37+ BuildZoom-verified permits in the public registry.

FEMA Substantial Improvement screening before quoting. A contractor who hasn't checked your home's pre-improvement market value, your 12-month permit history, and your specific flood zone before pricing your addition is not running the screening that protects your project from a $200K–$400K scope expansion mid-build. Every Gaven site visit covers FEMA SI math first.

Structural engineer relationships, not "we'll find one." Second-story additions and load-bearing wall removals require a stamped structural engineer's set. We work with licensed Florida structural engineers we've used across multiple projects — not a vendor we Google after contract signing.

In-house crews, single point of accountability. The framing crew, finish crew, and project manager that show up on day one are the same names on day 365. We don't outsource project supervision to general subcontracted trades and bill it as "GC services."

Written warranty and lien releases standard, not on request. Every project carries a written 1–2 year labor warranty. Sworn partial payment affidavits at every draw. Final Contractor's Affidavit and lien releases at completion. Florida's Construction Lien Law gives every supplier and subcontractor a lien right against your property — the affidavits are how you stay protected from double-payment exposure.

The five traits above don't disqualify other contractors. They give you the operational vocabulary to compare additions builders on what actually matters during a 4–15 month project, rather than on which firm has the smoother sales pitch.

Most home addition clients live in the home during construction. That is doable, and the discipline that makes it doable is a real cost driver worth naming.

We build a temporary partition wall between the existing conditioned space and the new construction zone before any envelope of the existing house is opened. Dust control runs on negative-pressure air scrubbers in the work zone. MEP shutdowns get scheduled in advance with you, not announced the morning of: water main off, panel de-energized, HVAC shut down for tie-ins. Crews enter and exit through a designated path that doesn't run through your living space. Work hours follow whichever jurisdiction's permitted window applies, which in most Miami-Dade and Broward residential zones is roughly 7 AM to 7 PM Monday through Saturday.

Two project moments are hard to stay through: the day the new construction ties into the existing structure (the day the existing exterior wall becomes interior, or the existing roof opens for a second-story tie-in), and final HVAC commissioning when both systems run together for balance. On second-story additions, two to four nights elsewhere during the roof tear-off is common. The rest of the project is livable with planning.

Home additions across Miami-Dade County (full county), Broward County (full county), and Palm Beach County (full county). HVHZ jurisdictions in Miami-Dade and most of Broward shape the envelope spec on the new portion. Coastal flood-zone work in any of the three counties brings the FEMA 50% rule into play. Inland work in Palm Beach County, parts of west Broward, and parts of west Miami-Dade runs without the flood-zone layer and with a different envelope spec.

We do not build outside this footprint.

Most of our addition projects include a kitchen or bathroom built into the new square footage. Those are the projects that define the firm.

If your addition's centerpiece is a new kitchen, the kitchen page goes deeper, with full pricing tiers, cabinetry and stone references, and a 15-question FAQ.

If it's a new bathroom or primary suite, the bathroom page goes deeper, with full pricing tiers, fixture references, waterproofing standards, and a 15-question FAQ.

If your project is multi-room renovation without footprint expansion, the home remodeling page covers whole-home and multi-room scope inside the existing envelope.