Accessory Dwelling Units are one of the fastest ways to add housing and long-term value in Los Angeles. Choosing how you deliver the project is just as important as selecting the footprint.
The two most common paths are Design-Build and the traditional Architect plus General Contractor model. Each can produce a great ADU.
They differ in how budgets are set, how decisions are made, and who bears the risk when surprises arise.
Discover innovative design ideas for room additions in Sherman Oaks that increase square footage and lifestyle flexibility.
The Design-Build approach: Integrated team, single contract
What it is
Design-Build combines design and construction under one roof, with a single contract for the homeowner. The builder leads the process, pairing designers, engineers, estimators, and permit specialists from day one. You receive one point of contact, one consolidated scope, and one full-project number to track.
Where Design-Build shines for ADUs in Los Angeles
- Complex back-of-lot logistics. ADUs often sit behind the main house with tight access, utility upgrades, and neighbor protections. Early builder input on trench routes, crane access, and staging avoids redesigns.
- Cost visibility before you fall in love with drawings. Pricing is developed in parallel with design. As soon as massing and systems are sketched, the team reconciles cost to target, then locks the scope before permit.
- Streamlined approvals. An integrated team can tailor drawings to city submittal checklists, manage corrections quickly, and align structural, energy, and green code details from the start. If you choose a pre-approved or standard plan variant, plan check often moves faster because fewer details need re-review.
- Speed to site. With one contract, procurement can start earlier. Long-lead items, such as panels, windows, or heat pumps, are queued while the last minor plan comments are being resolved.
- Fewer change orders. Because constructability is vetted during design, surprises that cause rework tend to be minimized. When conditions shift, the team problem-solves internally rather than negotiating across separate firms.
Actionable tips if you choose Design-Build
- Request a concept-to-permit schedule that illustrates the overlap between design, estimating, and submittal phases.
- Require a pre-construction deliverables list that includes utility load calculations, a preliminary site logistics plan, and a value-engineering log for review.
- Align on a target price with allowances for finishes and site work. Confirm how allowances are reconciled at buyout.
- Request sample submittal packages from recent LA ADUs to see drawing quality and correction turnaround.
Potential drawbacks to plan for
- Design options can feel more limited if you do not request alternative schemes. Insist on at least two plan iterations at the concept stage.
- Pricing transparency varies by firm. Request an open-book cost report with trade-level breakdowns and a transparent fee structure outlined in the contract.
Architect + GC model: Separate specialists, two contracts
What it is
The traditional path involves retaining an architect to create and coordinate the plans, then bidding the completed set to one or more licensed general contractors. The owner holds one contract with the architect and a separate agreement with the builder.
Where Architect + GC works well for ADUs
- Design-driven or site-sensitive cases. If your property requires a unique solution, a design-first process can explore more options before cost becomes a factor.
- Competitive bid preferences. Owners who want multiple price proposals on a fully detailed set may prefer to bid at 100 percent drawings.
- Existing designer relationship. If you already trust an architect who knows your property and block, the continuity can be valuable.
Actionable tips if you choose Architect + GC
- Hire an architect with a clear scope that includes zoning analysis, engineering coordination, energy documentation, and permit corrections.
- Add a pre-bid cost check at 50 percent drawings to catch budget creep early.
- When bidding, issue a bid instructions sheet that standardizes alternates and exclusions, allowing you to compare bids apples to apples.
- Plan for architect site observation during construction to resolve details quickly and document conformance.
Risks to manage
- Split accountability. If something is missing or unclear, responsibility can become a matter of ping-ponging between the designer and the builder. Avoid this by defining an RFI response time and change order protocol in both contracts.
- Longer preconstruction. Design is often completed before contractor input, which can extend the calendar if re-design is needed after bids arrive.
Cost comparison: How each method impacts your budget
Fee structure and markups
- Design-Build. Typical pricing bundles preconstruction, design, and construction services with a single fee and markup. You gain early cost certainty, but you must ensure pricing is competitive. Ask for two rounds of independent cost checks or a second internal estimate.
- Architect + GC. You pay the architect separately for design, engineering coordination, and permit support, and then pay the builder’s price after the bid is awarded. You may gain bid competition but risk redesign costs if bids exceed the target.
Where costs commonly move on LA ADUs
- Utilities. Electrical service upgrades, sewer connections at the alley or street, trenching around mature trees, and stormwater compliance are frequent budget movers.
- Foundation and grading. Rear yard soil conditions, retaining needs, and drainage swales can add concrete and earthwork.
- Envelope and MEP. Fire-rating at the ADU-to-property line, acoustic targets near neighbors, and all-electric systems with heat pump water heaters and mini-splits can shift allowances.
- Finish scopes. Small footprints magnify finish choices. Cabinetry, tile, and glazing selections can quickly add up the dollars.
Actionable cost controls in either model
- Set a target range on day one and show how size and spec decisions lead up to it.
- Use an allowance matrix that tracks owner-selected items against the target as you shop.
- Lock the site plan early to freeze utility routes and grading quantities.
- Confirm fees and impact charges early. Fee caps and exemptions often apply to smaller ADUs, but you still need to account for plan check, school district, and utility fees that are not impact fees.
- Buy early, store smart. Long-lead equipment and windows should be procured as soon as plans are approvable to protect the schedule and pricing.
Speed of completion: What changes your timeline in Los Angeles
What accelerates the front end
- Pre-approved or standard plans. Selecting a plan that has been pre-vetted for code compliance can shorten the plan check process and reduce the number of rounds of corrections.
- Complete submittals. Zoning diagrams, energy forms, structural calcs, and clear site utilities reduce resubmittals.
- Early utility coordination. LADWP power upgrades, gas capping if going all-electric, and sewer tie-in approvals should be triggered as drawings reach permit-ready.
Design-Build vs Architect + GC on time
- Design-Build tends to move faster from concept to permit because design and estimating run in parallel, and constructability is resolved as drawings evolve. The same team that draws the details builds them, which cuts down on clarification time during construction.
- Architect + GC typically places most of the effort before bidding. If bids land over budget, redesign may add weeks. During construction, design clarifications may require additional architect involvement to maintain pace.
The owner moves that protect the schedule.
- Approve plan decisions in batches at defined checkpoints to avoid drip changes.
- Choose readily available products or confirm lead times before approving premium selections.
- Assign a single owner representative to respond to RFIs and selections on a set cadence.
Risk assessment: Who carries what, and how to protect yourself
Contract structure and accountability
- Design-Build. One entity is accountable for both design and construction. When field conditions differ from assumptions, the integrated team has a built-in mechanism to resolve the issue—your risk shifts to choosing the right team up front.
- Architect + GC. The owner manages two relationships: explicit scopes and timely decisions control risk. Add meeting notes and submittal logs to maintain a clean paper trail.
Permitting and compliance risk
- LA ADUs are reviewed ministerially when plans meet the rules. That is a benefit, not a guarantee of zero corrections. Standardized submittals, code expertise, and quick responses reduce correction cycles.
- If you are near a coastal zone, hillside, or special overlay area, add lead time and obtain planning input before finalizing the site plan.
Construction risk
- Preconstruction site walks should verify access, setbacks, trees, drainage paths, and utility routes to ensure compliance with local regulations.
- Require a QA checklist for waterproofing, fire-rated assemblies, and inspections at slab, framing, rough MEP, and finals.
- Verify license, insurance, and bonding for the builder and key subs. Request additional insured endorsements and verify workers’ compensation coverage.
Actionable protections regardless of method
- Write a tight scope exhibit. Include unit size, ceiling heights, window schedule, equipment model numbers, and sitework quantities.
- Define change management. Approvals must be in writing, including pricing and time impacts, before work proceeds.
- Hold a contingency. Carry a sensible owner contingency for unforeseen conditions.
- Set response times. RFIs, submittals, and correction responses should have clear turnaround times.
- Close out cleanly. Withhold a portion of payment until you receive final inspections, manuals, warranties, and as-built PDFs.
How to choose between the two for your property
- Select Design-Build if your priority is speed to permit and construction, you want a single accountable team, and you value early cost certainty with fewer handoffs. This is especially strong for garage conversions, tight access sites, and repeatable layouts.
- Pick Architect + GC if you have a unique design vision, want competitive bidding on a fully detailed set, or already have a trusted architect. Build in time for iterative design and a pre-bid cost check to protect the budget.
Los Angeles rewards a disciplined, well-coordinated ADU process. Design-Build concentrates responsibility and often moves fastest when the scope is precise and repeatable. Architect plus GC offers design freedom and bid competition but demands tighter owner management. Select the method that aligns with your goals for cost, schedule, and risk. If you need help evaluating which path is best for your site, FTR Renovation & Build can model both timelines and budgets, allowing you to make an informed decision with confidence.