Updated February 2026

The "Backyard Bonus" ADU Protocol: High-Yield Garage Conversion Checklist

Zoning & Feasibility Scouting

Verify your "hidden" equity before breaking ground to ensure compliance and profitability.

  • Confirm setback requirements (typical: 4ft from side/rear property lines)
  • Verify easement clearances (sewer, electrical, utility poles)
  • Check local lot coverage ratio limits (e.g., maximum 45% coverage)
  • Analyze parking replacement requirements (some cities waive this for ADUs)
  • Review Owner-Occupancy deed restrictions for rental permits
  • Inspect existing foundation slab integrity for garage conversions
  • Calculate height restrictions (usually limited to 16ft for single story)
  • Determine fire separation distance requirements from main dwelling
  • Check HOA bylaws for restrictions on detached structures
Pro Tip: ROI Tip: Look for 'Transit-Oriented Communities' (TOC) zones. Many municipalities waive parking requirements and density limits if you are within 0.5 miles of a major transit stop.

Structural & Shell Fortification

Turning a simple storage shell into a permitted habitable dwelling class.

  • Retrofit garage door opening with framed shear wall and window package
  • Install moisture barrier under framing if existing slab lacks vapor barrier
  • Upgrade wall framing to 2x6 where possible for higher R-value insulation
  • Level floors with self-leveling concrete compound (vital for LVP)
  • Install fire-rated drywall (Type X, 5/8") on walls facing property lines
  • Ventilation: Ridge vent or solar-powered attic fan installation
  • Vault ceilings if structural tie-beams allow to increase visual volume
  • Reinforce door headers to accommodate security-grade entry doors
  • Seal all rim joists and sill plates with expanding spray foam
Pro Tip: Construction Hack: If vaulting the ceiling isn't possible, use 'Solar Tubes' instead of traditional skylights. They fit between standard trusses, require no framing changes, and bring in massive natural light for under $400/tube.

Compact Utility Infrastructure

Routing independent systems to handle load without upgrading the main house.

  • Install independent sub-panel (60-100 Amp) directly from the drop
  • Select tankless water heater (exterior mount) to save interior square footage
  • Route sewer line tie-in: Confirm slope grade meets code (1/4 inch per foot)
  • Install mini-split HVAC system (12k BTU typical for <400 sq ft)
  • Add separate water meter or dedicated sub-meter for bill-back capability
  • Use PEX plumbing for flexibility in tight retrofit walls
  • Pre-wire CAT6 ethernet backhaul to main house router location
  • Install EV charging rough-in (NEMA 14-50) near designated parking
  • Dedicate circuits for heavy appliances (Induction cooktop, Dryer)
Pro Tip: Utility Script: Ask your plumber for an 'ejector pump' quote immediately if gravity slope is questionable. Knowing this cost upfront prevents a $4,000 surprise mid-project.

Micro-Kitchen & Cooking Efficiency

Delivering full-service culinary capability in less than 8 linear feet.

  • Utilize 24-inch 'Apartment Size' refrigerator and range
  • Install single-bowl deep sink (maximize counter space over double bowl)
  • Choose microwave-hood combination to vent cooking fumes
  • Use open shelving above sink to reduce visual bulk/cabinet weight
  • Implement pull-out pantry tower (9-inch width) for dry storage
  • Select 18-inch dishwasher (or dishwasher drawer) for efficiency
  • Install continuous countertop material (Quartz) into window sill
  • Add magnetic knife strip to replace counter block
  • Recessed toe-kick drawers for storing flat pans or overflow items
Pro Tip: Design Trick: Use an induction cooktop inset into the counter instead of a standalone range. When not in use, it doubles as extra counter workspace, which is gold in an ADU.

Wet-Room Bathroom Architecture

Creating a spa-like experience within a tight footprint.

  • Install pocket door entry to save 9 sq ft of swing clearance
  • Use curbless shower design with linear drain to expand visual floor area
  • Mount vanity on wall (floating) to reveal flooring underneath
  • Install recessed medicine cabinet (mirrored inside and out)
  • Place toilet tank inside wall cavity (wall-hung) if space is critical
  • Vent fan timer switch implementation (prevent mold liability)
  • Large format tile (12x24 minimum) to minimize grout lines
  • Install backlit mirror to eliminate need for bulky sconces
  • Add niche shelving inside shower framing (no protruding caddies)
Pro Tip: Layout Tip: Align the bathroom plumbing wall with the kitchen plumbing wall ('wet wall'). Sharing one stack significantly reduces plumbing rough-in labor and materials.

Dual-Purpose Sleeping & Living

Furniture that works overtime to define separate zones.

  • Source specialized 'Murphy Desk' (wall bed with integrated workspace)
  • Use acoustical slat wood wall panels for headboard sound dampening
  • Install blackout cellular shades (top-down/bottom-up variety)
  • Position TV mount on full-motion arm for view from bed or sofa
  • Select sofa with chaise storage for linens and seasonal gear
  • Use rigid core luxury vinyl plank (LVP) throughout (no carpet transitions)
  • Install dimmer switches on all zones for evening ambiance
  • Add floating nightstands to facilitate floor cleaning
  • Secure tall wardrobes to studs for safety and built-in look
Pro Tip: Buying Advice: For rentals, avoid 'mechanical' furniture with complex moving parts that tenants can break. Stick to a static platform bed with hydraulic lift storage underneath rather than a complex wall-bed if possible.

Private Entry & Security Layering

Ensuring the ADU feels like a standalone home, not a guest room.

  • Establish designated lighted pathway separated from main house patio
  • Install keyless smart lock (Z-Wave/Zigbee) integrated with property management
  • Mount video doorbell specifically for the unit address (Unit B)
  • Plant privacy hedging (Clumping Bamboo or Ficus) between units
  • Install motion-sensor floodlights on corners away from windows
  • Number the unit clearly with 4-inch reflective house numbers
  • Add locking mailbox cluster at street level
  • Gate security: Self-closing spring hinge on side access gate
  • Create dedicated refuse bin storage area hidden from view
Pro Tip: Postal Standard: Ensure you officially register the address as 'Unit B' or '1/2' with the USPS early. A tenant being unable to receive mail is a top reason for turnover in ADUs.

Final Finishes & Value Add

The cosmetic touches that justify top-tier rental rates.

  • Paint walls in 'Greige' or warm white (e.g., SW Alabaster) to reflect light
  • Install heavy-duty coat hooks (4+) near entry (no space for closet)
  • Add full-length mirror on back of bathroom door
  • Upgrade to solid-core interior doors for sound isolation
  • Install washer/dryer unit (stackable) in a vented closet
  • Place focused task lighting under kitchen cabinets
  • Provide starter 'welcome kit' consumables for first week
  • Ensure all window screens are heavy-duty pet resistant mesh
  • Install smart thermostat capable of remote landlord lockout settings
Pro Tip: Market Value: An in-unit washer/dryer in an ADU allows you to charge premium rent (often +$150/month). Never skip laundry in a standalone unit.

Frequently Asked Questions

How much does it cost to convert a garage into an ADU?

While costs vary by location, a typical 400 sq. ft. garage conversion generally lands between $45,000 and $90,000 depending on utility access and finish quality. Ground-up detached construction typically starts closer to $150,000 due to foundation and framing costs.

Does adding an ADU trigger a property tax reassessment?

In most jurisdictions (including California), building an ADU adds a 'blended value' assessment rather than triggering a full property reassessment. You will pay additional tax only on the value added by the new construction, not on your existing home.

Is separate metering for utilities required for ADUs?

Separate metering is usually optional but highly recommended for long-term rentals to minimize disputes. A cheaper alternative is installing 'sub-meters' which allow you to track usage internally without paying the utility company for a brand new commercial service drop.