Backyard homes are now a mainstream option for adding living space, generating rental income, and increasing property value across Los Angeles County. In Pasadena and the City of Los Angeles, homeowners can choose between standard ADU plans and custom ADU designs, each offering distinct trade-offs in terms of cost, speed, and flexibility.
This guide explains how these options work locally and how to choose the right path for your lot, budget, and timeline.
Understanding Accessory Dwelling Units (ADUs) in Pasadena
Accessory Dwelling Units are independent residential structures on a lot with a primary home. California’s streamlining reforms require ministerial approvals on a predictable schedule, and they limit local barriers, such as significant setbacks and specific fees. Pasadena updated its ADU regulations in 2024 and offers a city-run Standard Plans program that pre-reviews a selection of ADU designs.
Los Angeles also operates a Standard Plan program through its building department, in conjunction with a countywide program for unincorporated areas.
What this means for you in Pasadena:
- You can pursue a pre-reviewed Standard Plan that has already been checked for building code compliance, then supply a site plan that shows how the ADU fits your lot.
- You can also pursue a custom design to match unique site constraints, aesthetics, or program needs.
- Junior ADUs and interior conversions remain options for smaller budgets or when the yard area is limited.
Actionable steps to start right:
- Pull a recent copy of your parcel survey, title report, and any easements.
- Measure side and rear yards and sketch candidate ADU footprints at least four feet off the side and rear lot lines, unless your site requires different standards.
- Identify utility tie-in points and clearances on your site sketch.
- Decide early whether you want a rental unit, a family suite, or aging-in-place features; this choice determines the size, layout, and mechanical needs.
The Advantages of Standard ADU Plans
Standard plans are pre-reviewed architectural sets offered by the city or approved designers. They are designed to cut plan-check time and reduce soft costs.
Why homeowners pick Standard Plans:
- Faster approvals: Since building and green code compliance is pre-checked, plan review primarily focuses on site-specific items, such as foundation, grading, utilities, fire setbacks, and any special hazards.
- Lower design fees: You avoid a full custom architectural scope.
- Predictability: Floor plans, structural systems, and energy compliance are set, which reduces redesign cycles.
Limitations to weigh:
- No or minimal modifications: Standard plans are typically “as-is.” If you want to move windows, adjust the roof form, or change structural spans, you will likely leave the standard path.
- Site conditions still matter: Hillside lots, mature trees, flood or fire zones, and unusual utility runs can require additional engineering, even with a standard plan.
- Curb appeal tradeoffs: Standard elevations may look clean, but they may not align with homes in Pasadena’s neighborhoods or preservation areas without careful site planning and finish choices.
Pro tip: Before you commit, request a site-fit check from your builder or design team. They will overlay the selected standard plan on your survey to confirm clearances, trench paths, utility loads, and accessible routes.
The Benefits of Custom ADU Designs for Unique Needs
Custom design unlocks layout control, premium finishes, and detailed coordination with your existing house and landscape.
When custom shines:
- Tight or irregular lots: Non-rectangular parcels, corner conditions, or slopes benefit from custom footprints and stepped foundations.
- Architectural alignment: If you want a craftsman-inspired façade, with matching roof pitches, batten patterns, or wood details, custom design allows it without compromise.
- Programmed spaces, such as offices, music rooms, caregiver suites, or accessibility features like no-threshold showers, more expansive halls, and integrated ramps, are easier to incorporate from the first sketch.
- Value engineering: You can tailor structural spans, window sizes, and systems to hit a target price per square foot without overbuilding.
Actionable design moves that add value:
- Keep the structure’s width efficient for standard lumber lengths and common truss packages.
- Group plumbing in short runs to limit slab penetrations and trench lengths.
- Use a simple roof form that meets energy goals without excessive framing complexity.
- Pre-plan storage walls that double as shear walls so you pay once for structure and function.
Cost Comparisons: Standard Plans vs Custom Designs in Los Angeles
Actual costs vary by lot, size, and finish level, but local ranges help with early budgeting.
Typical hard-cost and soft-cost patterns:
- Garage conversions are often the lowest total cost because you reuse the existing shell and slab.
- Small detached ADUs, 400–800 sq. ft.: Generally midrange; foundations, utilities, and site work drive variability.
- Larger detached ADUs, 800–1,200 sq. ft.: Higher totals due to bigger foundations, more conditioned space, and higher window and finish counts.
- Prefab or panelized options can shorten on-site work, although site preparation, crane logistics, and utility trenching still apply.
Where Standard Plans can save:
- Design fees and plan-check rounds: Pre-reviewed sheets reduce the need for back-and-forth comments.
- Schedule risk: Known details reduce redesign delays.
Where custom can be worth it:
- Appraisal and rent: A better-performing layout, higher-quality windows, and improved curb appeal can command stronger rent and valuation.
- Avoiding change orders: A plan tailored to your site can prevent last-minute fixes that offset any up-front design savings.
Line-item budgeting tips:
- Add allowances for trenching, panel upgrades, and service laterals.
- Set an allowance for site drainage and hardscape restoration.
- If your unit is 750 sq. ft. or smaller, confirm which local impact fees do not apply, then allocate funds you save toward finishes or solar storage.
Permitting and Approval Processes for Standard vs Custom ADUs in Pasadena
Standard Plan path:
- Select an approved plan, prepare a site plan, and submit it with the required forms through Pasadena’s online portal.
- Plan check focuses on how the pre-reviewed building aligns with your specific lot, including trees, utilities, grading, and zoning constraints.
- Because the building set is pre-reviewed, corrections often come faster and in fewer rounds.
Custom path:
- Submit a complete architectural set, structural calculations, Title 24 energy documents, and a detailed site plan.
- Expect the usual corrections for structural details, energy compliance, fire separation, and site engineering.
- In both paths, approvals are ministerial when your design complies with the standards, which means that there are no discretionary hearings in typical cases.
Pasadena-specific considerations:
- The city has continued to align its ordinance with state law while iterating its local processes. Check the current submittal checklist and any updates to plan types, fees, and tree protections.
- Pasadena’s Standard Plans generally cannot be modified. If your site or aesthetic needs require changes, switch to a custom route early rather than trying to push exceptions late in plan check.
Timeline planning checklist:
- Order a survey and utility load letter before design is locked.
- If using a Standard Plan, schedule a pre-submittal meeting to confirm site-specific requirements, such as tree protection, driveway access, and fire apparatus clearances.
- Hold a weekly standing check-in with your builder during plan check so field constraints are resolved before permits are issued.
- Ask your electrician and plumber to walk the site and sign off on trench routes and elevations before you pour any slab.
When to Choose Standard Plans Over Custom Designs and Vice Versa
Choose a Standard Plan if:
- Your lot is relatively flat and rectangular with clear side and rear yard space.
- You want a predictable floor plan, a quicker plan-check experience, and a lower design fee.
- You are comfortable selecting finishes and exterior colors within a fixed elevation.
Choose a Custom Design if:
- You need exact window placements for privacy, light, or views.
- Your site has slope, heritage trees, or utility conflicts that demand tailored foundations or footprints.
- You seek a specific architectural language that closely complements your primary home or a local historic context.
- You want advanced features such as accessible entries, decoupled sound assemblies, high-performance windows, battery storage, or radiant heating.
Multifamily owners:
Recent statewide changes increased the number of detached ADUs allowed on lots with existing multifamily buildings.
If you own a duplex or apartment property, a feasibility study can confirm how many detached ADUs fit on your site, where to place them, and how to phase construction to manage tenant impacts.
Making the Right Choice Between Standard and Custom ADU Designs in Pasadena to Meet Your Needs
Start with the site. If the footprint and utility routes are straightforward, a Standard Plan can reduce soft costs and keep your schedule tight. If the lot is complex, your program is specific, or design quality is central to rent and resale, custom is the safer path.
Either way, build a clear pre-construction playbook that covers survey, utilities, tree protections, drainage, and finishes. That plan will protect your budget and timeline far more than any single design choice.
Next step with FTR:
Transform your Malibu property with high-end custom ADU designs tailored for luxury and functionality.