Junior ADU & Interior Conversion in Lantana, FL - Scope, Timeline & Cost
Junior ADU & Interior Conversion in Lantana typically runs $45,000-$130,000 and takes 8-14 weeks from permit to final inspection, depending on whether you’re reconfiguring an existing interior footprint or adding conditioned space within the envelope. Most Lantana homeowners call us at (844) 665-0162 after realizing their 1960s concrete block home has underutilized square footage that could become a self-contained living unit with its own kitchenette, bath, and separate entrance. The job isn’t a full addition; it’s surgical - reworking plumbing, electrical, and structure inside the existing walls while meeting Palm Beach County’s strict wind and flood codes.
How We Approach Junior ADU & Interior Conversion Step by Step
Every junior ADU & interior conversion we handle in Lantana follows a five-stage sequence. Homeowners who understand the rhythm make better decisions faster, which keeps the schedule intact.
Stage 1: Feasibility and Flood-Code Review (1-2 weeks)
Before we touch a wall, we pull the FEMA flood map for your parcel and cross-check Palm Beach County’s property appraiser records. Lantana’s low-lying position on the Intracoastal Waterway means many homes sit in AE flood zones, and if your project crosses the 50% “substantial improvement” threshold, the permit transforms into a flood-elevation compliance event. We’ve seen a straightforward interior conversion near Hypoluxo Island suddenly require slab elevation because the combined assessed value and renovation cost triggered the threshold. We price this possibility into our initial estimate so you’re not facing a five-figure surprise mid-project.
Stage 2: Design and Material Selection (2-3 weeks)
This is where you decide what the unit actually becomes. We measure every existing condition - ceiling height, electrical panel capacity, plumbing stack locations, window sizes - and present options that fit within the constraints. You’ll choose between compact kitchenette layouts (two-burner cooktop versus full range), wet-bath versus full shower stall, and whether to add a separate HVAC mini-split or extend the existing system. We also spec impact-rated windows and exterior doors at this stage; Palm Beach County requires them on all substantial renovations, and Lantana’s salt air demands stainless or hot-dipped galvanized hardware to prevent fastener corrosion.
Stage 3: Permits and Pre-Construction (2-4 weeks)
We submit to Palm Beach County’s building department with structural drawings, MEP plans, and flood-compliance documentation if triggered. Inspection scheduling in this county runs tighter than some South Florida municipalities, but we’ve worked the rhythm long enough to avoid common submission errors that cost weeks. While permits process, we order long-lead items: impact windows, pre-hung exterior doors, and any custom cabinetry.
Stage 4: Demolition and Rough Construction (3-5 weeks)
The existing interior comes out - sometimes down to block walls, sometimes preserving select partitions depending on the layout. We re-route plumbing and electrical, install new framing where needed, and rough in the kitchenette and bath. This is the noisiest, dustiest phase, and we sequence it to minimize disruption if you’re living in the main house during construction.
Stage 5: Finishes, Fixtures, and Final Inspection (2-3 weeks)
Cabinets, countertops, flooring, tile, paint, and final electrical and plumbing fixtures go in. We use a punch-list walkthrough with you before calling for the county’s final inspection. Typical hold items at this stage in Lantana: verifying hurricane strap connections on any modified roof-to-wall junctions, and confirming exterior door impact ratings match the permit submittal.
The Spec Choices That Shape Your Junior ADU & Interior Conversion
Every junior ADU & interior conversion in Lantana forces trade-offs between budget, durability, and daily usability. Here’s what you’ll actually decide:
- Kitchenette footprint: A 24-inch two-burner cooktop with under-counter fridge and microwave drawer runs lean and keeps electrical demand modest - smart for older panels. A full 30-inch range with dishwasher and standard refrigerator needs a 200-amp service upgrade more often than not, adding $3,500-$6,000 but delivering real cooking capacity.
- Countertop material: Laminate survives budget-focused rentals but shows wear fast in Lantana’s humidity. Silestone and Caesarstone engineered quartz resist moisture and salt-air corrosion without the sealing demands of natural stone; we spec these for owners planning long-term use or short-term rental income.
- Bath configuration: A wet bath (shower over toilet, wall-hung sink) fits in 35 square feet and keeps plumbing relocation minimal. A separate shower stall with vanity needs more space and more pipe runs, but it’s what most tenants and adult family members expect.
- Flooring: Luxury vinyl plank handles moisture and installs fast over concrete slab, which is what most Lantana homes sit on. Tile lasts longer but feels cold and raises floor height, which can create threshold issues with existing doors.
- HVAC: A dedicated mini-split gives the unit independent climate control and avoids overloading the main house’s aging system. Extending existing ductwork is cheaper upfront but often means the junior ADU & interior conversion never quite heats or cools evenly.
- Exterior door and hardware: Impact-rated fiberglass or steel with stainless hinges and multi-point locking. In Lantana, we won’t install anything less; the wind code requires it, and the salt air destroys standard hardware in three years.
What Junior ADU & Interior Conversion Costs in Lantana, FL
Junior ADU & interior conversion in Lantana typically costs $45,000-$130,000. Here’s what pushes a project toward the low or high end of that range:
| Cost Driver | Low-End Impact | High-End Impact |
|---|---|---|
| Square footage converted | 300-400 sq ft, existing plumbing nearby | 600+ sq ft, extensive reconfiguration |
| Electrical panel | 100-amp panel with spare capacity | Upgrade to 200-amp service required |
| Plumbing relocation | Kitchenette and bath on existing wet wall | Moving drain lines through concrete slab |
| Material grade | Stock cabinetry, laminate counters, vinyl plank | Custom cabinets, quartz counters, tile, impact upgrades |
| Flood-code trigger | Below 50% threshold, standard permit | Full flood-elevation compliance, engineering, potential slab work |
A written estimate from us includes demolition, rough and finish carpentry, plumbing and electrical rough-in and trim, impact-rated windows and exterior door, kitchenette and bath fixtures, flooring, paint, and permit fees. It does not include furniture, window coverings, or landscaping repair from equipment access. If flood-code compliance triggers, elevation and engineered foundation work price separately after we confirm the threshold calculation with the county.
Call (844) 665-0162 for a free on-site estimate - we’ll bring the flood map and assessed-value data so you know where you stand before any contract.
Why Lantana’s Homes and Codes Make This Job Different
Lantana’s housing stock shapes every junior ADU & interior conversion we bid. The town is almost entirely built out with post-WWII concrete block stucco homes from the 1950s through 1970s - flat or low-slope built-up roofs, original jalousie windows, and electrical panels that predate modern hurricane and energy codes. These aren’t obstacles; they’re parameters we design around.
The flood-code reality is what separates Lantana from inland Palm Beach County towns. That 1962 CBS home near the Intracoastal might have a property appraiser value of $280,000, meaning any renovation exceeding $140,000 triggers full flood-elevation compliance. A junior ADU & interior conversion with kitchen, bath, electrical upgrade, and impact windows can easily approach that figure. We pull the map and the number before we quote, not after.
Salt-laden air less than a mile from the Atlantic corrodes exposed metal faster than homeowners expect. We specify stainless or hot-dipped galvanized hurricane strapping, fasteners, and flashing on every project - not as an upgrade, but as baseline. And Palm Beach County’s post-Andrew wind code means every substantial renovation must verify roof-to-wall connections and install impact-rated openings. The compliance cost is real, but it’s priced in from day one, not discovered at inspection.
Many Lantana properties also carry HOA deed restrictions from original 1960s subdivisions. We review these during feasibility; some associations still prohibit separate entrances or exterior door modifications that a true junior ADU requires.
Serving Lantana, FL - Our Local Coverage Area
We’re based in the Lantana 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 - Junior ADU & Interior Conversion in Lantana
Most projects finish in 8-14 weeks, with permit approval adding 2-4 weeks upfront. Flood-code triggers or HOA architectural review can extend that by several weeks. Call (844) 665-0162 and we’ll check your specific parcel timeline.
Yes - Palm Beach County requires building permits for any structural, plumbing, or electrical modification, and a certificate of occupancy for the new unit. We handle the submittal and inspection scheduling as part of our scope. Call (844) 665-0162 for a free estimate that includes permit fees.
Sometimes, if the existing layout already clusters a bathroom and kitchenette against a wet wall. Most Lantana homes from the 1960s and 70s don’t offer that convenience, so expect at least partial relocation. We design to minimize concrete slab cutting, which is the cost driver. Call (844) 665-0162 and we’ll show you what’s possible in your specific floor plan.
A wet-bar-style kitchenette with mini-fridge, microwave, and two-burner cooktop runs $4,500-$8,000 installed, versus $12,000-$18,000 for a full appliance package with range, dishwasher, and standard refrigerator. The trade-off is cooking capacity and whether your electrical panel can handle the load. Call (844) 665-0162 for an exact quote based on your panel and layout.
We warranty our workmanship for one year and pass through all manufacturer warranties on materials - typically 10 years on cabinets, lifetime on quartz countertops like Silestone and Caesarstone, and limited lifetime on impact windows and doors. Call (844) 665-0162 for written warranty details with your estimate.
Start With a Free On-Site Estimate in Lantana
Junior ADU & interior conversion in Lantana isn’t a cookie-cutter job - the flood codes, the salt air, and the 1960s housing stock demand a contractor who knows the local territory. We’ll walk your property, check the FEMA map and assessed value, and give you a written estimate with real numbers. Call (844) 665-0162 to schedule. Raymond Estevez and our team serve Lantana and nearby Palm Beach County communities.
Homeowners exploring a full Home Additions & ADU in Lantana often start with a junior unit to test the concept before committing to a larger Home Additions & ADU project. Many also pair their conversion with Kitchen Design & Layout in Lantana or Small & Partial Kitchen Remodels in Lantana to refresh the main house while the ADU takes shape.
Written by Raymond Estevez, Owner at Groundwork Construction Co., serving Lantana since our founding.