Junior ADU & Interior Conversion in Boulder City, NV
A Junior ADU & Interior Conversion in Boulder City turns an existing bedroom, den, or attached living space into a self-contained unit with its own kitchenette, bathroom, and separate entrance, typically running $45,000-$130,000 and taking 8-14 weeks from permit approval to final inspection. Unlike a detached ADU, this stays within your home’s footprint, which matters in Boulder City where the 1% annual growth cap makes every square foot of existing structure more valuable than new construction. Call (855) 951-4361 and we’ll walk your property, identify the best candidate space, and give you a written estimate with upfront pricing, no surprises.
How we handle a Junior ADU & Interior Conversion from first call to final walkthrough
We’ve learned that Boulder City homeowners, especially those on acreage outside the historic core, want the job done right in one trip. The permitting queue here punishes callbacks and change orders. Here’s how we sequence every Junior ADU & Interior Conversion to avoid that.
Stage 1: Feasibility and zoning check (Days 1-5)
We visit your property, measure the candidate space, and verify it meets Boulder City’s junior ADU requirements: maximum 500 square feet, attached to the primary dwelling, with its own exterior door. For homes in the 1930s historic district near Nevada Way, we also flag whether design review applies. You’ll decide at this stage whether to proceed with the full permit application or explore a simpler interior conversion without the separate entrance. We photograph existing electrical panels, plumbing stacks, and HVAC ducting so there are no surprises later.
Stage 2: Design and material selection (Days 6-14)
This is where you make the decisions that drive your final number. Kitchenette layout: linear galley against one wall, or L-shaped with a small peninsula? Bathroom: wet bath with combined shower/toilet area, or separate fixtures with a 32-inch shower stall? Flooring: luxury vinyl plank for moisture resistance, or tile for durability? We specify moisture-stabilized lumber for any exterior wall modifications, standard for Boulder City’s sub-10% humidity. Your written selections lock in before permit submission so material lead times don’t stall the job.
Stage 3: Permit submission and queue (Days 15-35)
We file with Boulder City Planning, which operates under the 1% growth cap allocation system. Junior ADU permits typically move faster than new detached units, but the queue still exists. We handle all plan sets, energy compliance documentation, and any required historic district review. If your property borders Bureau of Reclamation land, we flag early whether federal easement coordination is needed. Most of our Boulder City Junior ADU & Interior Conversion permits clear in 2-3 weeks; we stay in weekly contact with the city so you aren’t left guessing.
Stage 4: Construction (Days 36-75)
Demolition is surgical: we remove only what’s necessary to run new electrical circuits, plumbing lines, and the separate entrance door. For 1960s ranch homes in the Elks Point or Broadbent areas, we often find original aluminum wiring or galvanized plumbing that needs replacement to meet current code. We install a mini-split HVAC unit sized for 500 square feet, run 20-amp kitchenette circuits, and rough in the wet wall. Inspections happen at rough electrical, rough plumbing, and framing. We schedule them tightly to avoid the delays that kill momentum.
Stage 5: Finish and final inspection (Days 76-95)
Cabinets, countertops, fixtures, flooring, paint, and the final electrical/plumbing trim. We use flexible, UV-rated exterior sealants around the new entrance door, not standard caulk, because Boulder City’s 110°F summers destroy the cheap stuff in two seasons. Final inspection with the city, certificate of occupancy, and your walkthrough. The 730-Day Done Right Promise starts that day.
The real choices that shape your Junior ADU & Interior Conversion
Every option below is a fork in the road that changes cost, durability, and who the space works for. We don’t upsell; we explain the trade-off and let you decide.
- Kitchenette: appliance grade. A two-burner induction cooktop with a convection microwave drawer runs $2,800-$4,200 installed and suits a tenant who cooks lightly. A full 24-inch electric range with range hood bumps that to $4,500-$6,800 and opens the unit to longer-term renters or family members. The induction setup is safer, cooler in summer, and draws less amperage, which matters in older Boulder City homes with 100-amp panels.
- Bathroom: wet bath versus separate fixtures. A wet bath, where the shower floor is the bathroom floor with a curtain or glass panel, saves 15-20 square feet and $3,000-$5,000. Separate shower stall with a swing door feels conventional and resells better, but needs 32 inches clear. For the 500-square-foot maximum, the wet bath is often the smarter use of space.
- Flooring: LVP versus tile. Luxury vinyl plank at $4-$7 per square foot installed is warmer underfoot, faster to install, and handles the thermal expansion from Boulder City’s 50°F winter nights to 110°F summer days better than rigid materials. Tile at $8-$14 per square foot installed lasts longer but needs crack-isolation membrane over any slab with movement history. We see more slab-on-grade ranch homes in Boulder City than frame floors, so this matters.
- Separate entrance: retrofit existing window versus new cut. Converting a ground-floor window to a door costs $3,500-$5,500 if the wall is non-load-bearing and there’s no rebar in the block. A new cut in a concrete block wall runs $5,500-$9,000 with lintel, waterproofing, and stucco repair. We X-ray scan before quoting so you know which you’re facing.
- HVAC: mini-split versus extended ducting. A dedicated 9,000 BTU mini-split at $3,200-$4,800 installed gives the tenant independent climate control and doesn’t tax your main system. Extending existing ducting is cheaper at $1,800-$3,000 but often requires upsizing the main unit, which can trigger a full HVAC replacement in older homes. We calculate both paths during feasibility.
What Junior ADU & Interior Conversion costs in Boulder City, NV
Most Junior ADU & Interior Conversion projects in Boulder City fall between $45,000 and $130,000. The table below breaks where a typical job lands based on scope.
| Scope Level | Price Range | Typical Configuration |
|---|---|---|
| Entry: interior conversion, no separate entrance | $45,000-$68,000 | Wet bath, LVP flooring, induction kitchenette, existing HVAC extension |
| Mid: full junior ADU with separate door | $72,000-$98,000 | Separate entrance, 32-inch shower stall, tile wet areas, mini-split, upgraded cabinets |
| High: complex layout, structural modification, historic district | $105,000-$130,000 | Load-bearing wall removal, panel upgrade, historic review compliance, premium fixtures |
Five variables push you up or down that range. First, existing condition: 1930s concrete block with lime plaster needs more prep than 1970s drywall. Second, plumbing relocation: moving a toilet drain across a slab adds $4,000-$7,500. Third, electrical service: upgrading from 100 to 200 amps runs $3,500-$6,000. Fourth, material grade: Sterling plumbing fixtures versus standard builder grade is a $1,200-$2,800 spread across the unit. Fifth, permit complexity: historic district review or Reclamation easement coordination adds 2-6 weeks and $1,500-$4,000 in professional fees.
Our written estimate includes all labor, materials, permits, and inspections. It does not include appliance packages above baseline, window treatments, or furniture. We offer 0% financing for 18 months and $1,000 off projects over $10,000, which every Junior ADU & Interior Conversion qualifies for.
Why Boulder City itself changes how we build these
Boulder City isn’t Henderson. It isn’t Las Vegas. The 1% annual growth cap means the city treats every residential permit as a scarce resource, and the planning staff know their code cold. We’ve seen out-of-town contractors walk in with standard Clark County submittals and get sent back for rework because they missed Boulder City’s specific energy compliance worksheet or their site plan didn’t account for the city’s unique setback tables. We file correctly the first time because we’ve done it before.
The housing stock splits sharply. In the historic core around Nevada Way and Adams Boulevard, we work on 1930s Mission Revival homes built for Hoover Dam workers, original concrete block with lime plaster that demands compatible repair materials, modern Portland cement will destroy it. Those jobs trigger historic district design review, adding a layer most contractors don’t anticipate. Beyond the historic district, the 1960s and 70s ranch homes in neighborhoods like Elks Point and Broadbent have their own issues: aluminum wiring, galvanized plumbing, and slab-on-grade construction with minimal insulation. The Mojave Desert climate at 2,500 feet elevation hits everything hard. UV radiation destroys standard exterior caulk in two years, not ten. Sub-10% humidity splits wood trim and checks fascia boards. We specify moisture-stabilized lumber and flexible, UV-rated sealants on every exterior modification because we’ve seen what happens when we don’t.
And then there’s the federal land issue. Properties near the city edge, especially anything with a view of Lake Mead or backing up to Bureau of Reclamation land, may need federal easement review that has nothing to do with Boulder City Planning. We’ve seen jobs stall six months because a contractor started work without checking. We check first.
Homeowners often pair a Junior ADU & Interior Conversion with Kitchen Design & Layout in Boulder City for the main house, or with Small & Partial Kitchen Remodels in Boulder City to refresh the primary kitchen while the secondary one is being built. If you’re considering this as part of a full property reconfiguration, see our broader Home Additions & ADU in Boulder City page, or explore how our Home Additions & ADU crew approaches larger-scale work across the region. We cover Boulder City from the historic core to the acreage properties on the city’s southern edge.
Serving Boulder City, NV - Our Local Coverage Area
We’re based in the Boulder City 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 Boulder City
From permit approval to final inspection, most Junior ADU & Interior Conversion projects take 8-14 weeks. The permitting queue itself adds 2-3 weeks in Boulder City due to the 1% growth cap allocation system, which is longer than Henderson or Las Vegas but manageable with proper submittals. Call (855) 951-4361 for a free estimate and we’ll give you a realistic timeline based on your specific property.
Yes, and it’s not a simple over-the-counter permit. Boulder City requires full plan review for any junior ADU, including electrical, plumbing, and energy compliance. Homes in the historic district need additional design review. We handle the entire submittal and shepherd it through the queue. The permit cost is included in our written estimate.
Sometimes, but it’s rare. Most candidate spaces, bedrooms or dens, aren’t located near existing plumbing stacks, so at minimum you’ll need a new toilet drain and vent run, typically $3,500-$6,500. Electrical almost always needs a dedicated 20-amp kitchenette circuit and GFCI protection. During our feasibility visit, we map what’s existing versus what’s required so you know before committing.
Usually, but not always. A Junior ADU & Interior Conversion avoids foundation and roofing work, which saves $8,000-$15,000. However, if your candidate space needs structural modification, like removing a load-bearing wall for flow, or if the home needs an electrical service upgrade, the gap narrows. We quote both paths when it makes sense so you can compare.
Every Junior ADU & Interior Conversion is backed by our 730-Day Done Right Promise, if it’s not done right, we make it right. That’s one of the longest workmanship guarantees in residential construction. Material warranties from manufacturers like GAF or CertainTeed run separately and vary by product. We document both at final walkthrough so you have everything in writing.
Get your free estimate for Junior ADU & Interior Conversion in Boulder City
Call (855) 951-4361 and a live person will answer, 24/7. We’ll schedule a no-pressure site visit, walk your candidate space, and deliver a written estimate with upfront pricing within 48 hours. Ask about 0% financing for 18 months and $1,000 off your project. From foundation to finish line, we build it to last and back it in writing.
Written by Todd Mervyn, Owner at Groundwork Construction Co., serving Boulder City since 2014.