Junior ADU & Interior Conversion Cost - Plans, Permits & Build, One Fixed Price

How Much Does Junior ADU & Interior Conversion Cost in West Hollywood?

Our Junior ADU & Interior Conversion services in West Hollywood typically cost between $80,000 and $180,000 all-in, drawings through final inspection. That range covers the full design-build scope: permit drawings, City of West Hollywood plan check, all construction, finishes, and the documented photo record Ellery ADU Studio includes on every project. Where your number lands inside that range depends almost entirely on the existing condition of the space and how much plumbing and electrical work the conversion requires.

Junior ADU & Interior Conversion Cost Breakdown (2026)

The table below reflects current West Hollywood market pricing as of 2026. Every line item listed here is quoted in writing before a single permit application is filed – that is Haven Standard, Clause 1, and it applies to every project without exception.

A few things pull projects toward the lower end of that range: the space already has a bathroom rough-in, the electrical panel was updated within the last decade, and no load-bearing walls need to come down. Projects that approach $180,000 typically involve older West Hollywood bungalows built before 1960, where the electrical service is 100 amps and the existing slab has no plumbing stub-outs at all. In those cases, the first thing the permit drawings reveal is what is already there – and that documentation is what drives an accurate written price, not a verbal estimate on a first phone call.

It is also worth understanding what a Junior ADU is, technically. Under California Health and Safety Code Section 65852.22, a JADU must be contained entirely within the walls of the primary dwelling (including an attached garage), cap out at 500 square feet, and share at least one wall with the main house. West Hollywood enforces those parameters closely. Our drawings address the shared-corridor requirement, the separate exterior entrance, and the efficiency kitchen standards the City checks for during plan review. If you want to understand the full scope of what an interior conversion project looks like in this market, the Junior ADU & Interior Conversion in West Hollywood service page walks through each phase.

What Affects Junior ADU & Interior Conversion Pricing in West Hollywood

• Existing plumbing location. The single biggest variable in any West Hollywood JADU budget is whether the conversion space sits near an existing plumbing stack. Older properties on Havenhurst Drive, Fountain Avenue, and the blocks south of Santa Monica Boulevard were often built with garages or storage rooms far from the main water and drain lines. Running new supply and drain across 20 or 30 feet of existing slab – through concrete, not just subfloor – can add $6,000 to $10,000 to the plumbing scope alone.
• Electrical service capacity. West Hollywood’s housing stock includes a significant number of pre-1965 structures that are still running 100-amp service. A JADU with a kitchen, bathroom, and mini-split system needs dedicated circuits that a 100-amp panel simply cannot support safely. An electrical service upgrade to 200 amps runs $4,500 to $8,000 depending on LADWP service point distance and metering configuration. The permit drawings will flag this before construction begins, not during it.
• Structural conditions. Converting an attached garage or ground-floor flex room in a multi-story building often means addressing a load-bearing wall where the new exterior door will go. In older West Hollywood properties, the framing may not be documented anywhere. Our team opens the wall during pre-construction investigation – and what we find goes into the written scope before the contract is signed, not as a change order after demo.
• Title 24 energy compliance. California’s energy code requires that newly created habitable space – which a JADU is – meet current insulation, glazing, and HVAC efficiency standards. For a conversion of a space that previously had no insulation (a common situation in pre-1970 West Hollywood garages), bringing the walls, ceiling, and any new windows into compliance adds $4,000 to $9,000 to the budget. The Title 24 compliance report is part of the permit set Ellery produces.
• Exterior entrance and egress. A JADU must have its own exterior entrance separate from the main dwelling’s primary entry. If the conversion space already has a door to the exterior, this is straightforward. If a new opening needs to be cut – through stucco, framing, and potentially a retaining wall – that structural work adds cost and requires its own detail in the permit drawings. West Hollywood’s Building and Safety division reviews exterior opening locations carefully on corner lots and properties near the setback line.
• Finish level. A JADU finished with LVP flooring, stock cabinetry, and a standard prefab shower enclosure comes in materially lower than one with engineered hardwood, semi-custom cabinets, and a tile walk-in shower. The structural and MEP work is largely fixed; finishes are where the client has genuine control over cost. Ellery will show you the written price for both scenarios before you decide.

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How to Save on Junior ADU & Interior Conversion

The most reliable way to control cost on a JADU project in West Hollywood is to front-load the investigation. The permit drawings are not just a regulatory requirement – they are the document that tells you exactly what the conversion will cost before any money is spent on construction. Skipping this step, or hiring a contractor who quotes verbally and permits later, is how projects go 30% over budget. At Ellery, the drawings come first, and the written price follows from what the drawings reveal.

Here is where experienced owners typically find real savings:

• Use the existing bathroom location. If the space being converted already has a bathroom – even a half-bath – building the JADU kitchen and bath on or near that existing plumbing stack saves the most money of any single decision. Moving a kitchen 15 feet away from the drain stack to improve the layout costs more than most clients expect.
• Sequence the panel upgrade into a planned project. If your property needs a 200-amp service upgrade regardless of the JADU (and in many West Hollywood properties it does), doing it as part of the conversion rather than as a standalone project saves on mobilization and permitting overhead.
• Choose finish tiers deliberately. The structural, plumbing, and electrical work is not where you save money – the inspectors see all of it. Finishes are the lever. LVP over engineered hardwood, semi-custom over fully custom cabinetry, and a prefab shower over a fully tiled enclosure can each save $3,000 to $6,000 without affecting the long-term value of the unit meaningfully.
• Avoid scope changes after permit issuance. Every revision to permitted drawings after City of West Hollywood plan check approval triggers a correction fee and delays the inspection schedule. The way to avoid this is to make every decision – layout, fixture locations, window openings – during the design phase, before the permit application goes in. That is exactly how the Ellery process works.
• Get a second opinion on any estimate already in hand. If you have received a written estimate from another firm, Ellery will review it for free. We look at what is included, what is not, and whether the numbers reflect current West Hollywood subcontractor and permit costs. There is no obligation and no sales pressure – just a clear read on whether the number in front of you is realistic for this market.

To get a written price on your specific project, call (213) 329-7167. A live person answers – not a voicemail queue. The estimate is free, it is written, and it covers the full scope from permit drawings through final inspection.

FAQs – Junior ADU & Interior Conversion Cost in West Hollywood

How much does a Junior ADU conversion cost in West Hollywood in 2026?

A Junior ADU conversion in West Hollywood typically costs $80,000 to $180,000 all-in, including architectural drawings, City permit fees, all construction, and finishes. The lower end of that range applies to spaces with existing plumbing rough-ins and updated electrical service. Projects in older pre-1965 structures with 100-amp panels and no existing plumbing in the conversion space land closer to $150,000 to $180,000. Every project Ellery undertakes is quoted at a single written price before work begins, per Haven Standard Clause 1 – so the number you are given is the number you pay, not a starting bid. Call (213) 329-7167 for a written estimate on your property.

What is the difference between a Junior ADU and a full ADU in terms of cost?

A Junior ADU is consistently less expensive than a full detached or attached ADU, primarily because it is contained within the existing footprint of the primary dwelling – no new foundation, no new roof, no exterior framing. In the West Hollywood market, a full detached ADU typically runs $250,000 to $420,000 all-in. A JADU in the same market runs $80,000 to $180,000. The trade-off is size: JADUs cap at 500 square feet under California law, while a full ADU can reach 1,200 square feet. For homeowners who have an underused attached garage or ground-floor room, the JADU path delivers a rentable or multigenerational unit at roughly half the cost of new construction. Call (213) 329-7167 to discuss which path makes financial sense for your property.

How long does a Junior ADU conversion take in West Hollywood?

From signed contract to final inspection, a Junior ADU conversion in West Hollywood takes approximately 6 to 10 months. The City of West Hollywood plan check currently runs 8 to 14 weeks for standard JADU submittals, depending on the complexity of the structural work and whether corrections are required. Construction, once permitted, takes 10 to 16 weeks depending on the scope. The design and permit drawing phase, which must happen before any application is filed, runs 4 to 6 weeks. Projects that involve complex structural work – load-bearing wall removal, slab plumbing, or new exterior openings – run toward the longer end of that construction window. Call (213) 329-7167 and we can give you a timeline estimate specific to your property type.

Do I need a separate meter for a Junior ADU in West Hollywood?

No – California law specifically allows a JADU to share utilities with the primary dwelling, which is one of the cost advantages of the JADU path. A separate electrical meter, water meter, and gas meter are not required. That said, the electrical panel in the primary dwelling must have enough capacity to support the added load from the JADU’s kitchen, bathroom, and HVAC system. In practice, roughly 60% of West Hollywood properties Ellery evaluates need at minimum a sub-panel addition to the JADU space, and a meaningful number need a full service upgrade from 100 amps to 200 amps. The permit drawings will document exactly what is required before construction begins. Call (213) 329-7167 for a written price that includes the electrical scope.

Is a Junior ADU worth it financially in West Hollywood?

At current West Hollywood rental rates – studios and one-bedroom units in the 90046 and 90069 zip codes are renting at $2,200 to $3,400 per month as of early 2026 – a JADU that costs $120,000 to build generates a gross annual rent of $26,400 to $40,800. That is a gross yield of 22% to 34% on construction cost before expenses, in a market where appreciation adds further value to the underlying property. The financial case is strong for most West Hollywood properties, particularly for homeowners who have a usable attached garage or ground-floor flex room sitting unused. The more useful question is whether the specific space on your property is convertible at a cost that makes the math work – and that is exactly what the permit drawings and written price reveal. Call (213) 329-7167 to start with a free, written estimate.

Key Takeaways

• Junior ADU conversions in West Hollywood run $80,000 to $180,000 all-in, drawings through final inspection.
• The biggest cost variables are existing plumbing proximity and electrical service capacity – both of which the permit drawings document before construction begins.
• Ellery provides a written price before any work starts on every project, per Haven Standard Clause 1. No verbal estimates, no post-demo surprises.
• The 365-Day Done Right Promise means if the finished JADU is not built to the permitted drawings, Ellery makes it right – in writing, before the project starts.
• City of West Hollywood plan check currently runs 8 to 14 weeks; total project timeline is 6 to 10 months from contract to final inspection.
• Free second opinion available on any written estimate already in hand – call (213) 329-7167.
• West Hollywood’s JADU rental market supports $2,200 to $3,400 per month, making the construction cost recoverable within 4 to 7 years at current rates.

Nadia Ellery and the Ellery ADU Studio team have been producing permit-ready JADU drawings and design-build contracts for West Hollywood homeowners since 2015 – across properties from the flat lots north of Melrose to the steeper topography near Laurel Canyon. The permit set is the core product. The written price and the 365-Day Done Right Promise are what make it possible to quote honestly in a market where construction costs shift quarter to quarter. If you have a written estimate from another firm, bring it – the second opinion is free and we will tell you directly whether the numbers hold up. To get a written price on your Junior ADU project, visit our home page or call (213) 329-7167 today.

Pricing reflects the West Hollywood market as of 2026. Ellery ADU Studio West Hollywood offers free estimates – call (213) 329-7167.

Written by Nadia Ellery, Owner at Ellery ADU Studio West Hollywood, serving West Hollywood since 2015.