Trusted Junior ADU & Interior Conversion for Long Beach Homeowners
A junior ADU or interior conversion in Long Beach typically runs $85,000-$175,000 all-in, from measured drawings through final inspection, depending on whether you’re converting existing square footage or adding attached space. See our guide on how much Junior ADU & Interior Conversion costs for a detailed breakdown. Ellery ADU Studio has designed, permitted, and built over 900 ADUs since 2015, the year California’s statewide ADU laws began reshaping how cities like Long Beach process these permits. Every project starts with a written price before any work begins, per Haven Standard Clause 1, and our live person answers calls 24/7 at (562) 414-4842.
Long Beach homeowners in neighborhoods like Belmont Heights, Bixby Knolls, and the Craftsman Village district face a specific constraint: lot sizes here often run 5,000-6,000 square feet, which makes a detached ADU tight on setbacks but leaves plenty of interior and attached-addition opportunities. Our design-build studio handles our Junior ADU & Interior Conversion in Long Beach, from the permit set and construction documents through the build itself, under one contract at one written price. That eliminates the designer-versus-builder blame gap that derails most ADU projects in Southern California.
We’ve worked with Long Beach’s Development Services on JADU permits since the city adopted its local ADU ordinance in 2017, and we understand how the Coastal Zone overlay affects certain blocks near Ocean Boulevard and Belmont Shore. Our permit sets are built to pass the first time, not to generate change orders later.
What Our Junior ADU & Interior Conversion Service Includes
Basement ADU
A basement ADU converts below-grade space into a self-contained dwelling unit with its own kitchen, bathroom, sleeping area, and separate exterior entrance. In Long Beach, this works particularly well for homes in the Bluff Heights and Alamitos Heights areas, where older properties often have full basements with 7.5- to 8-foot ceiling heights that meet code with minimal excavation. At Ellery ADU Studio Long Beach, we start with a geotechnical assessment and moisture intrusion survey, then design the egress window placement and ventilation system to satisfy Long Beach’s specific interpretation of the California Residential Code’s light and air requirements for basement dwellings.
Above-Garage ADU
An above-garage ADU, sometimes called a carriage house conversion, adds living space on top of an existing or rebuilt garage structure. This is common in Long Beach’s Rose Park and California Heights neighborhoods, where 1920s and 1930s garages are often freestanding at the rear of deep lots. We evaluate the existing foundation’s load capacity, design a structural upgrade if needed, and coordinate the fire separation between garage and living space per Long Beach Fire Department requirements. Our permit set includes the structural calculations, MEP plans, and energy compliance documentation that the city requires before they’ll issue the building permit.
Room-to-ADU Conversion
A room-to-ADU conversion transforms an existing bedroom, den, or accessory space within the primary residence into a Carson Junior ADU & Interior Conversion-style junior accessory dwelling unit with its own entrance, kitchenette, and bathroom facilities. This is the lowest-cost path for Long Beach homeowners who need rental income or multigenerational space without exterior construction. We verify that the proposed JADU meets the 500-square-foot maximum and that the owner-occupancy requirement can be documented per California Government Code Section 65852.22. Our drawings show exactly how the kitchenette fits, where the separate entrance goes, and how the utilities are metered or submetered.
Attached Addition ADU
An attached addition ADU extends the primary residence with new construction that creates a separate dwelling unit sharing at least one wall. In Long Beach’s Plaza and Wrigley areas, where lots are narrower but R-1-R-2 zoning allows greater density, this often means building outward into the side yard or rear yard within setback limits. We handle the site plan showing compliance with Long Beach’s 4-foot side and 10-foot rear setbacks, design the fire-rated wall assembly between units, and specify the independent utility connections or shared-meter agreement that the city will accept.
Interior JADU
An interior JADU is the specific California classification for Junior ADU & Interior Conversion in San Pedro and similar junior accessory dwelling units created entirely within the walls of an existing single-family home, with no exterior footprint change. Long Beach processes these as ministerial permits without discretionary review, which means faster approval if the permit set is complete. We produce the floor plan showing the 150-square-foot minimum and 500-square-foot maximum, the elevation showing the separate exterior door, and the electrical plan showing how the JADU connects to existing or new service. Our construction team then builds to those drawings, with a documented photo record on every visit.
What happens when you call
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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.
Brands We Service for Junior ADU & Interior Conversion
Ellery ADU Studio specifies and coordinates prefab and modular systems from Plant Prefab, Tuff Shed, and James Hardie within our single-contract design-build model. With Plant Prefab, we’ve integrated their LivingHome modules into attached-addition ADUs where the factory-built unit ties into site-built structure at the property line in Long Beach’s Zaferia district. Our permit sets show the exact connection details, the crane placement for delivery, and the utility tie-in points that Plant Prefab’s engineering requires for local approval.
We’ve used Tuff Shed’s installed structures as the shell for above-garage ADUs and interior-adjacent conversions in Belmont Shore, upgrading their standard framing to meet residential energy code and adding the insulation, MEP, and finish systems in our construction phase. James Hardie siding and trim products are our default specification for any exterior work on attached additions or above-garage units in Long Beach’s coastal climate, where salt air degrades lesser materials within five years. Whether your project involves these brands or conventional stick-built construction, we design, permit, and build under one written price.
Before
AfterSigns You Need Junior ADU & Interior Conversion Right Now
- Your mortgage payment has risen faster than your income. Long Beach homeowners who bought between 2019 and 2022 are seeing payment increases of $800-$1,400 monthly on reassessed or refinanced loans. A permitted JADU renting at $1,400-$1,900 in neighborhoods like Bixby Knolls or Stearns Park covers that gap with a tenant who has their own entrance and kitchenette.
- An aging parent needs proximity, not a facility. The median monthly cost of assisted living in Los Angeles County exceeds $5,000. Converting a ground-floor room or basement to a JADU keeps family close for a fraction of that, with the equity staying in your Long Beach property instead of going to a facility operator.
- Your adult child has moved back but needs independence. The “boomerang” generation is real in Long Beach, where median rents for a one-bedroom apartment now exceed $2,100. A room-to-ADU conversion gives them separate space without the friction of shared bathrooms and kitchens, and your property value increases with the permitted square footage.
- You’re sitting on unfinished basement or garage space that’s costing you money. Unconditioned square footage in Long Beach’s older homes drives up insurance premiums, attracts moisture and pests, and depreciates your assessed value. Converting it to permitted living space turns a liability into an income-producing asset with a documented permit history.
- Long Beach’s ADU ordinance is tightening, not loosening. The city has already reduced parking requirements and adopted the statewide 60-day ministerial review, but coastal zone properties and historic districts face additional scrutiny. Starting your permit set now locks in current rules before local amendments add cost or delay.
Our Junior ADU & Interior Conversion Process - Step by Step
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Site Measure and Feasibility Study - We visit your Long Beach property with a laser measure, moisture meter, and structural assessment checklist. Within 48 hours, you receive a written feasibility report showing what conversion type fits your zoning, your existing structure’s condition, and your budget range. This report includes a preliminary floor plan and a written price before any work begins, per Haven Standard Clause 1.
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Permit Set Development - Our in-house designers produce the full construction document set: architectural plans, structural calculations, MEP plans, Title 24 energy compliance, and Long Beach-specific forms. We submit to Development Services and handle all plan-check corrections. The permit set is the core product, not an afterthought, and we don’t start construction until it’s approved.
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Pre-Construction Walkthrough and Scope Lock - With permit in hand, we walk the site with you, mark the exact construction boundaries, and lock the scope in writing. Under Haven Standard Clause 5 (No Surprises), the price is fixed at signing. No door-side upsells, no scope creep, no “we found something unexpected” add-ons that weren’t in the original drawings.
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Construction with Documented Photo Record - Our background-checked, uniformed crews build to the permitted drawings. You receive a documented photo record on every visit showing what was found, what was done, and what comes next. This isn’t a summary of how it felt; it’s evidence of the work, stored in your client portal for review at any time.
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Final Inspection and 365-Day Done Right Promise - We schedule Long Beach building, fire, and utility inspections, correct any punch-list items, and deliver your final permit card and certificate of occupancy. Then our 365-Day Done Right Promise takes effect: if the finished ADU is not built to the permitted drawings, Ellery makes it right, in writing, before the project starts. That’s Haven Standard Clause 7, and it’s in every contract we sign.
How Much Does Junior ADU & Interior Conversion Cost in Long Beach?
A typical interior JADU conversion in Long Beach runs $85,000-$125,000 all-in, from measured drawings through final inspection. Room-to-ADU conversions at the simpler end, with existing plumbing nearby and no structural changes, tend toward the lower bound. Basement ADUs with moisture remediation, egress window cutting, and full MEP runs push toward $140,000-$175,000. Above-garage ADUs fall in the middle at $110,000-$155,000, depending on whether the existing garage structure can carry the load or needs rebuilding.
Attached addition ADUs, which involve new foundation work and roof ties, typically range $130,000-$190,000 in Long Beach’s market, where labor rates and material costs track slightly above the state median. These figures include the permit set, all city fees, construction, and our project management. They do not include optional upgrades like high-end finishes or solar arrays, which we quote as separate line items under Haven Standard Clause 1.
Several factors move the price within these ranges. The age of your Long Beach home matters: pre-1940s properties in Bluff Park or Belmont Heights often need electrical service upgrades, asbestos surveys, or lead-safe work practices that add $8,000-$15,000. Proximity to utilities affects plumbing and HVAC costs; a room at the far end of a long ranch house costs more to serve than one above the garage. And coastal zone properties may require additional corrosion-resistant materials or California Coastal Commission review, which we identify in the feasibility study before you commit.
To avoid overpaying, get the permit set right the first time. A rejected plan set at Long Beach Development Services costs four to eight weeks, and every week of delay carries holding costs. We build our permit sets to pass because we’ve processed over 900 ADUs since 2015 and we know what this city expects. Our free estimate includes a written scope, a written price, and a clear statement of what’s excluded, so you can compare apples-to-apples with any other bid. We also offer a Free Second Opinion on any written estimate already in hand.
Junior ADU & Interior Conversion Near Long Beach - Our Service Area
Ellery ADU Studio Long Beach serves homeowners throughout the greater Long Beach metro, including Junior ADU & Interior Conversion in Lakewood, Junior ADU & Interior Conversion in Carson, and projects in Cerritos, Cypress, Compton, Norwalk, Downey, Buena Park, San Pedro, Westminster, and Torrance. Typical permitting timelines run 8-14 weeks in Long Beach proper, slightly longer in coastal zone subareas, and 6-10 weeks in neighboring cities with less backlog. We maintain active permit relationships with each jurisdiction, so we know which plan checker is handling ADUs this month and what they’re flagging.
Our crews are based in Long Beach and don’t commute from outside the county, which means site visits happen on schedule and superintendent availability tracks with your project phase, not someone else’s across town. Whether you’re in the Craftsman Village district considering a basement ADU or in Lakewood Village weighing a room conversion, we measure, design, permit, and build under one contract at one written price.
Serving Long Beach, CA - Our Local Coverage Area
We’re based in the Long Beach 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 Questions - Junior ADU & Interior Conversion in Long Beach
A Junior ADU (JADU) is a specific California classification: a dwelling unit of 150-500 square feet created entirely within an existing single-family home, with a separate entrance, kitchenette, and either its own bathroom or shared bathroom access. An interior conversion can also refer to larger attached ADUs or basement conversions that don’t meet the JADU size cap. The key difference from a detached ADU is that a JADU requires owner occupancy of either the primary residence or the JADU itself, and it’s processed as a ministerial permit without discretionary review in Long Beach. Call (562) 414-4842 to discuss which classification fits your property.
From signed contract to certificate of occupancy, a typical interior JADU in Long Beach takes 4-6 months: 6-10 weeks for permit set development and approval, 8-12 weeks for construction, and 2-3 weeks for inspections and final corrections. Basement and above-garage conversions run 5-7 months due to structural and MEP complexity. These timelines assume a complete permit set submitted correctly the first time, which is why we treat the drawings as the core product, not an afterthought. Call (562) 414-4842 for a timeline specific to your property.
Interior JADU conversions in Long Beach typically cost $85,000-$125,000 all-in; basement ADUs run $140,000-$175,000; above-garage ADUs fall at $110,000-$155,000; and attached additions range $130,000-$190,000. Every project is quoted with a written price before any work begins, per Haven Standard Clause 1, with no “call for a quote” vagueness. The exact figure depends on your home’s age, utility locations, and finish selections, which we document in the feasibility study. Call (562) 414-4842 for your written estimate.
We specify and coordinate Plant Prefab and Tuff Shed systems where they fit the project, though interior conversions and JADUs are typically site-built due to the tight spatial constraints and existing-structure integration required. For attached addition ADUs and above-garage units with sufficient delivery access, we’ve integrated Plant Prefab modules and used Tuff Shed shells as the structural base. James Hardie products are our standard specification for any exterior finish work. Call (562) 414-4842 to discuss whether prefab or stick-built suits your specific Long Beach property.
Junior ADU and interior conversion work is planned construction, not emergency repair, so we don’t frame it as same-day dispatch. However, a live person answers our phones 24/7, and we can schedule a site visit within 48 hours for urgent situations like water intrusion in a basement conversion or structural concerns in an above-garage project. For true emergencies affecting occupant safety, we coordinate with licensed trades we trust and document everything for the permit record. Call (562) 414-4842 and a live person will pick up.
Every project includes our 365-Day Done Right Promise: if the finished ADU is not built to the permitted drawings, Ellery makes it right, backed in writing before construction starts under Haven Standard Clause 7. This covers workmanship, material installation, and compliance with the approved permit set. Beyond our promise, manufacturer’s warranties apply to specific products like James Hardie siding or Tuff Shed structural components. We deliver all warranty documentation at project closeout, not upon request months later. Call (562) 414-4842 for the full Haven Standard terms.
Gather your property’s assessor parcel number, any existing survey or plot plan, and your rough budget range. If you’ve received another written estimate, bring it for our Free Second Opinion. We’ll handle the zoning research, the code analysis, and the measured drawings during our site visit. There’s no obligation, no deposit required for the feasibility study, and no “call for a quote” runaround. Call (562) 414-4842 to schedule your consultation at your Long Beach property.
Schedule Your Junior ADU & Interior Conversion Service in Long Beach Today
Call (562) 414-4842 to schedule your free estimate. A live person answers 24/7, and you’ll receive a written price before any work begins, per Haven Standard Clause 1. Whether you’re converting a basement in Bluff Heights, adding above a garage in Rose Park, or carving out a JADU in Bixby Knolls, Ellery ADU Studio Long Beach designs, permits, and builds under one contract with a documented photo record on every visit and our 365-Day Done Right Promise in writing.
Written by Nadia Ellery, Owner at Ellery ADU Studio, serving Long Beach since 2015.