Define Intended Use
How you plan to use your ADU should drive every design decision—from layout and finishes to utility planning and privacy features. Get clear on your primary use case now to avoid expensive changes later.
Quick Summary
Time to decide
1-2 weeks
Most common use
Rental income
Key consideration
Future flexibility
Common ADU Use Cases
ADUs serve many purposes, and your use case significantly impacts design priorities:
Long-Term Rental Income
The most popular use case. Generate $1,200-3,000+/month depending on your market, size, and finishes. Pays off mortgage or funds retirement.
Design priorities:
- • Separate entrance and maximum privacy
- • Durable, easy-clean finishes
- • Full kitchen with standard appliances
- • Good storage (renters accumulate stuff)
- • Laundry (in-unit or hookups)
- • Parking consideration
Aging Parent (In-Law Suite)
Keep parents close while maintaining independence. Growing rapidly as population ages. Often called "aging in place" design.
Design priorities:
- • Single-level, no stairs (ADA-friendly)
- • Wide doorways (32"+ clear width)
- • Walk-in shower with seat, grab bars
- • Lever door handles, rocker switches
- • Internal connection option to main house
- • Emergency alert system wiring
- • Good lighting, non-slip floors
Adult Child Housing
Young adults saving for homes, boomerang kids, or recently graduated children. Provides independence while staying connected.
Design priorities:
- • Strong privacy and separate entrance
- • Full kitchen for independence
- • Work-from-home space consideration
- • Modern finishes and amenities
- • Good internet infrastructure
- • May convert to rental later
Home Office / Studio
Dedicated workspace separate from main house. Popular for remote workers, therapists, artists, or anyone needing professional space.
Design priorities:
- • May not need full kitchen (kitchenette OK)
- • Excellent internet/tech infrastructure
- • Sound insulation if client-facing
- • Professional entrance for visitors
- • Half bath may suffice (check if full required)
- • Can convert to rental if work needs change
Guest Suite
Comfortable space for visiting family and friends. May also serve as short-term rental (Airbnb) when not hosting guests.
Design priorities:
- • Hotel-like amenities and finishes
- • Kitchenette may be sufficient
- • Quality bed and linens storage
- • Good bathroom with tub/shower option
- • Easy-to-use climate control
- • Proximity to main house for family visits
Short-Term Rental (Airbnb/VRBO)
Higher income potential than long-term rental in tourist areas, but requires more management. Check local regulations—many cities restrict or ban STRs.
Design priorities:
- • Instagram-worthy aesthetic
- • Smart locks for keyless entry
- • Easy cleaning between guests
- • Full kitchen (guests expect it)
- • Outdoor space if possible
- • Sound separation from main house
- • Storage for linens and supplies
Planning for Multiple Uses
Life changes. The smartest ADU designs accommodate multiple potential uses:
Future-Proof Design Strategies
Include full kitchen
Even if you don't need it now—converting later is expensive
Build accessibility features now
Wide doors, reinforced bathroom walls for grab bars, single-level if possible
Maximize privacy
Separate entrance and sound insulation work for any use
Run extra wiring
Network cables, extra outlets, EV charger prep—cheap now, expensive later
Consider separate utilities
Separate meters make rental management much easier
Common progression: Many homeowners start with ADU as home office or family housing, then convert to rental once circumstances change. Design for this flexibility from the start.
Regulatory Considerations by Use
Short-Term Rental Restrictions
Many cities limit or prohibit short-term rentals. Some require owner occupancy, cap rental nights per year, or ban STRs in ADUs entirely. Research before designing specifically for Airbnb.
Owner Occupancy Requirements
Some jurisdictions require the property owner to live in either the main house or the ADU. This affects your options—you can rent the ADU OR the main house, but not both simultaneously.
Home Business Regulations
If using ADU for business (therapy practice, etc.), check home occupation permits. Client visits, signage, and parking may trigger additional requirements.
Use Case Decision Worksheet
Primary intended use:
Secondary/future use (if primary changes):
Must-have features for your use:
Frequently Asked Questions
Can I change the use after building?
Yes, ADUs can change uses without new permits in most cases. The physical space is flexible—what changes is how you use it. The key is building in flexibility from the start (full kitchen, accessibility, privacy).
What if I'm unsure about the primary use?
Design for rental, which has the most demanding requirements (full kitchen, separate entrance, laundry, privacy). This configuration works for virtually any other use too, so you maintain maximum flexibility.
Do I need to tell the city what I'll use it for?
Generally no—you're permitting a dwelling unit. Some cities ask about intended use for data collection, and some have restrictions (owner occupancy, STR limits) that affect how you can use it. But the permit is for the structure, not the use.
Should I involve future occupants in design?
If building for a specific person (aging parent, adult child), absolutely involve them. Their input on layout, accessibility, and finishes ensures the space works for their needs. Generic rental units need market-appeal design instead.
Ready for the Next Step?
With your ADU type, size, and use defined, it's time to move into the Design Phase. You'll start by hiring an architect who specializes in ADU projects.