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ADU design and construction in Pasadena and Los Angeles

Detached units, garage conversions and JADUs, permitted end to end.

ADU Construction by ArcLine Builders — Altadena and Greater Los Angeles

An accessory dwelling unit is the highest-return square footage most Los Angeles homeowners will ever build — housing for family, rental income, or a place to live on your own lot while the main house goes up. State law has made them far easier to permit than they were a decade ago. Getting one built well is still entirely down to who builds it.

1,200
max sq ft, detached
6–9
months, typical build
60
day statutory permit review
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Why us

What you get that you would not get elsewhere.

  • The rebuild play most people miss

    If you are rebuilding after the fire, an ADU can be permitted and completed first, giving you somewhere to live on your own property while the main house is under construction. It ends the rent clock early and it is a strategy we have sequenced before.

  • We know which lots work

    Setbacks, utility capacity, sewer connection, existing panel size and access for equipment decide what is buildable and what is a permit rejection. We assess all of it before you spend money on design.

  • Built like the main house

    Our ADUs get the same envelope detailing, the same finish standard and the same fire-hardened assemblies as a custom home. Nothing about them should read as an outbuilding.

Scope of work

Exactly what is included.

A real scope, not a feature list. If something you need is missing here, ask — the answer is usually yes.

Types we build

  • Detached new-construction ADUs up to 1,200 sq ft
  • Attached ADUs and additions
  • Garage conversions
  • Junior ADUs within the existing footprint
  • ADU plus main-house rebuild, sequenced together

Included

  • Feasibility and lot assessment
  • Architectural design and Title 24
  • Permit submittal and plan-check management
  • Utility separation, panel upgrade and sewer connection
  • Full construction, finishes and appliances
  • Landscape, fencing and private entry

How it works

The same six steps, every project.

Durations are honest ranges. You will always know which step you are in and what has to happen to reach the next one.

  1. 01

    Consultation

    We walk the property with you, listen to what you want and give you an honest read on feasibility and budget range. No charge, no obligation, and no pressure to sign at the kitchen table.

    Week 1

  2. 02

    Planning & Scope

    We document the real scope — for rebuilds, that means reading your insurance estimate line by line against what the work actually costs. You get a written scope and a number you can plan around.

    Weeks 2–4

  3. 03

    Design

    Architectural drawings, structural engineering and Title 24, priced as they develop so the budget conversation happens while changes are still cheap. You approve the design before it is submitted.

    2–4 months

  4. 04

    Permits

    We submit to LA County or your city, respond to every plan-check correction and pull the permit. You are not standing at a counter, and you are kept up to date on where the submittal stands.

    2–4 months

  5. 05

    Construction

    One project manager, a published schedule and regular progress updates with photos. Change orders are priced and signed before the work happens, never discovered on an invoice.

    6–18 months

  6. 06

    Completion

    Final inspections, certificate of occupancy, a punch list we finish rather than argue about, and an organised warranty and maintenance handover.

    Final 4 weeks

Questions

ADU Construction, answered.

How much does an ADU cost in Los Angeles?

A well-built detached ADU generally runs $350 to $550 per square foot all in, including design, permits and utility work. Garage conversions cost less per foot but frequently need foundation, drainage and structural upgrades that narrow the gap. Site conditions matter more than square footage.

How long does ADU approval take?

California law requires agencies to approve or deny a complete ADU application within 60 days. Design and engineering before that take one to three months, and construction six to nine. Budget roughly a year from first conversation to move-in.

Can I build an ADU while rebuilding the main house?

Yes, and it is often the smartest sequence after a fire. The ADU is smaller, permits faster and finishes first, so you can move onto your property while the main house is still framed. We coordinate both permits together.

Will an ADU add to my property value?

Generally yes, though appraisers weigh rental income and local comparables more than raw square footage. A permitted, well-finished detached unit appraises considerably better than a converted garage.

Next step

Tell us what you are rebuilding.

A free estimate with a real scope and a real number. If the project is not right for us, we will tell you that too — and point you somewhere better.

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No cost · No obligation · Straight answers

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