ARCADIA · SAN GABRIEL VALLEY · GREATER LOS ANGELES
ADU Builder in Arcadia, CA
Detached ADUs, garage conversions and junior ADUs — coordinated, permitted and built by one team, with drawings and engineering by licensed design professionals and factory-direct cabinetry and materials.
ADU OPTIONS
Four ways to add a legal second unit.
Detached ADU
A standalone backyard home, typically 600–1,200 sq ft. Maximum privacy and flexibility for rental income, guests or a home office.
Garage Conversion ADU
Turn an underused garage into a studio or one-bedroom unit. Usually the most cost-effective route because the shell already exists. Whether it needs a permit depends on what the space becomes — do you need a permit to convert a garage.
garage conversion costs and permit rules →Arcadia residence whole-home proposal →
Junior ADU (JADU)
Up to 500 sq ft created within the existing home footprint — efficient for multi-generational living and subject to the applicable review process.
Attached ADU
An addition sharing a wall with the main house, integrated with the existing architecture and systems.
BUDGET
What an ADU costs in Arcadia.
Garage conversion
A reliable budget starts with the property and a defined scope. Existing structure, site access, utility capacity, floor area and premium finishes all affect the total. Compare itemized estimates for the same scope rather than a single cost-per-square-foot figure.
Detached ADU (600–1,200 sq ft)
Include new foundation and framing, site work and the full route of utility connections.
Permits, plan check and fees
Budget separately for design, engineering, permit review and utility work. City charges and connection requirements depend on the address and scope; confirm them before approving the construction budget.
Interior package
Cabinetry, countertops, flooring and fixtures are the most variable line — and the one where factory-direct supply changes the number.
Budget guidance is organized by scope rather than an advertised price. A project-specific written estimate should separate construction, design and engineering, permit fees, utility work, interior selections and contingency.
PERMITS & TIMELINE
How the Arcadia ADU process runs.
01 · Feasibility review
We look at lot dimensions, setbacks, existing structures, utility capacity and any unpermitted work already on the property — before you spend money on design.
02 · Design and engineering
Floor plan, elevations, structural calculations and Title 24 energy compliance, prepared for submittal.
03 · Permit submittal
We prepare and submit the application to the City of Arcadia Building and Planning Departments (Arcadia City Hall, 240 W Huntington Dr, Arcadia, CA 91007; Planning Division (626) 574-5423) and carry corrections through to an issued permit. California law requires a city to approve or deny a complete ADU application within 60 days; correction cycles vary by jurisdiction.
04 · Construction and inspection
Foundation, framing, trades, utility connections and finishes, scheduled with the required inspections and a final sign-off.
WHY US
Built for Arcadia’s housing stock.
Older homes, handled honestly
Older Arcadia homes can have several generations of alterations. Additions from that era often lack permits — we assess what is actually there and explain what legalising or removing it involves.
Factory-direct materials
Cabinetry, doors, wall panels and finishes come from our own production factory, so the interior package is specified and made together rather than sourced piecemeal.
One accountable team
Feasibility, permits, construction and the interior package run under one coordinated scope. Drawings and any structural calculations are prepared and stamped by licensed design professionals — we manage them, submit them and build to them, so there are no gaps between designer, contractor and supplier. The three companies behind that scope are described on the About page.
KWA Home · B General Contractor · #1145730
Coordinated interiors
The ADU is finished in the same material language as the main house, not treated as a separate afterthought.
WHO DOES WHAT
Design, permits and construction: who is responsible for what.
This is the part that most often gets muddled, so we state it plainly. KWA Home is not an architecture or design firm. We do not offer architectural design to the public, we do not stamp drawings, and we do not perform structural engineering. What we do is coordinate that work and build it.
Drawings and engineering
Prepared and stamped by licensed design professionals — a California-licensed architect for the plans, and a licensed structural engineer where structure, openings or load paths change. We supply the existing-condition information they depend on and coordinate the revisions the city asks for.
Permits
The building permit is submitted through the city portal and tracked to issuance, including plan review comments and the energy documentation that comes with the scope.
Construction
Our scope, under CSLB #1145730 — foundation, framing, wiring, plumbing, heating and cooling, insulation, drywall, finishes, inspection at each hold point, and handover.
Materials and cabinetry
Cabinetry, doors, wall panels and coordinated furnishings supplied factory-direct and installed after the walls are finished — specification decided early, measurement taken late.
FAQ
ADU questions we hear most.
How much does an ADU cost in Arcadia?
Confirm the dimensions, existing conditions and selected finishes in an itemized scope.
How long does an ADU permit take in Arcadia?
California law requires a city to approve or deny a complete ADU application within 60 days. In practice, correction cycles add time, so we plan the submittal to minimise rounds and tell you what to expect for your jurisdiction.
How big can my ADU be?
California sets statewide baselines (commonly up to 850 sq ft for a one-bedroom unit and 1,000 sq ft for two or more bedrooms; junior ADUs up to 500 sq ft), with local rules on height, setbacks and lot coverage. We confirm the exact envelope for your parcel during feasibility.
Do I need to add parking?
California law limits the parking a city can require for an ADU, and in many situations no replacement parking is needed — especially near transit. We verify this for your specific address.
Can I convert my existing garage?
Usually yes, and it is often the most cost-effective ADU route because the shell already exists. We check structure, slab condition, ceiling height and how utilities can be connected.
Can I rent the ADU out?
ADUs are commonly built for rental income, multi-generational living or a home office. Any rental use should follow current California and City of Arcadia rules, which we flag during planning.
Do you handle design, permits and construction?
We handle permits and construction, and we coordinate design and engineering. The drawings and any structural calculations are prepared and stamped by licensed design professionals — a California-licensed architect, and a licensed structural engineer where the scope needs one. That is what makes the submittal a stamped set rather than a sketch. See our six-stage process.
Can you supply cabinetry and materials as well?
Yes. Our own production factory supplies cabinetry, doors, wall panels and coordinated furnishings for the ADU. See building materials and custom furnishings.
How do I start?
Send us the address, what you want to build and any photos you have. We review feasibility first, then give a written scope. Request an ADU consultation.
One connected team.
Premium materials. Precise craftsmanship.
KWA Home
Coordinates residential construction.
CSLB #1145730
MIT Construction
Handles residential remodeling.
CSLB #964155
Winrun
Manufactures custom cabinetry and interior products.
Our specifications focus exclusively on premium materials and craftsmanship. The responsible contracting entity and scope are identified in your agreement.