ADU questions, answered

An accessory dwelling unit (ADU) is a small, independent living space on your property — with its own kitchen, bath and entrance. Homeowners build them for rental income, multigenerational living, a home office or an in-law suite, and a well-built ADU can add real long-term value to the property.

Garage conversions typically run $90,000-$150,000 ($150-$300 per sq ft); new detached ADUs $200,000-$450,000+ ($300-$450 per sq ft); attached units sit between. The site decides where you land in the range — access, utility runs, foundation and finishes — so we price from your real property conditions, not a brochure number. See the full cost guide.

Yes. A garage conversion is often a lower-cost path because the foundation, walls and roof may already exist. We inspect the shell first — slab, framing, ceiling height, drainage, fire separation and the utility route — then confirm whether converting is the best option before committing to it.

Yes. For our design-build ADUs we prepare the plan set, coordinate structural engineering and Title 24 energy compliance, submit to the city or county, respond to plan-check comments and schedule inspections during construction. The exact review path depends on your jurisdiction — we confirm the reviewing agency first instead of treating every city the same.

Timing has two parts: design and permitting, then construction. State law gives agencies review deadlines for complete applications, but the real calendar depends on submittal quality, correction rounds and city workload. We manage the process and keep you updated rather than promising a date the city controls. Construction itself moves on a fixed schedule once permits are issued.

Yes. We design and build ADUs, garage conversions and home additions across Orange County and Los Angeles — keeping architecture, permits and construction in-house so there is one team and one point of accountability.

With design-build, one licensed team owns the whole job — architecture, structural engineering, permitting and construction under one contract. That removes the gap between a separate architect and builder, keeps the budget and schedule accountable, and means your project moves from first sketch to final inspection without finger-pointing.

L Square Design & Build manages the full ADU process in Orange County as one in-house design-build team — architecture, structural engineering, permits and construction under a single contract (CSLB #1095476, 200+ ADUs completed across OC and LA). One contract means one point of accountability from first sketch to final inspection.

Turnkey means one team handles everything — and that is exactly the L Square model: feasibility, custom design, engineering, Title-24, the city submittal, construction by our own crews, and final inspections, all under one contract. You make the decisions; we run the project end to end. Start with a free on-site assessment: (949) 374-7980.

Judge any builder on four things: a verifiable CSLB license, completed detached-ADU volume, in-house design-plus-construction, and honest fixed quotes after seeing the lot. L Square holds CSLB #1095476 with 200+ completed units across OC and LA, and detached backyard homes are the core of our work — see the detached ADU guide.

Typically $90,000-$150,000 in Orange County and Los Angeles. The big movers are the slab (older garage slabs often need work), the electrical panel, and the sewer distance — not the finishes. Full line-item breakdown on the garage conversion page.

A junior accessory dwelling unit (JADU) is a unit of 500 sq ft or less created within the walls of an existing single-family home, with its own entrance and at least an efficiency kitchen. It is usually the lowest-cost path to a legal second unit, with one catch: state law requires owner-occupancy on the property. Details in the JADU guide.

Casita is simply the everyday Spanish-derived name for a small guest house — legally, a permitted casita in California IS an ADU and follows the same state rules: ministerial approval, size minimums and rentability. The word changes; the permit does not. More in our casita vs ADU comparison.

Verify the CSLB license number on the state website, ask for completed ADU addresses (not renderings), confirm design and construction sit under one contract, and distrust any firm quoting a firm price before walking your lot. We wrote a full checklist: how to hire an ADU contractor.

If your property has a single-family home in California, almost certainly yes — state law makes a code-compliant ADU approvable by right, with at least 800 sq ft allowed and 4-ft side and rear setbacks. What varies by lot is which type fits best: garage conversion, attached or detached. A free assessment answers it for your address — see the granny flat guide.

Affordable is a path, not a company: converting existing space costs least — a garage conversion ($90K-$150K) or a JADU within the home — because the structure already exists. Any builder promising detached-ADU prices far below the $200K+ market range is cutting something you will pay for later. We price both affordable paths against your lot honestly.

Yes, with a path choice: an attached ADU (including above-garage) is allowed up to 25 feet by right — the reliable two-story route — while a detached two-story depends on your city allowing height beyond the state 16-18 ft minimums. We check your city ordinance before design. Full rules in the two-story ADU guide.

Yes — the estimate is free and there is no pressure. Share your address, intended use and rough target size (photos of the yard, garage, electrical panel and access path help a lot), and we will walk you through what your property allows and a realistic budget before any commitment.