Thinking about adding an accessory dwelling unit to your property? You are not alone. ADUs have become the golden ticket for homeowners seeking to enhance property value, generate rental income, or accommodate family members. But between navigating zoning laws and passing that final inspection, the journey can feel overwhelming. We’re breaking down every step to make your ADU dreams a reality.
Understanding ADU Basics
ADUs aren’t just fancy sheds in your backyard. These independent living spaces come in multiple flavors—detached garages transformed into cozy apartments, basement conversions with separate entrances, attic renovations, or brand-new coach houses. The beauty of adu construction lies in its flexibility. Want a rental unit with full kitchen and bathroom? That’s one route. Prefer a home office or studio without the plumbing complexity? That works too.
Every ADU must have its own separate entrance, even when attached to your main home.
Navigating Zoning Regulations
Before you sketch floor plans or contact contractors, zoning is your first checkpoint. Here’s what matters:
- Check local ordinances – Many cities have lifted historical ADU bans, but regulations vary wildly
- Size restrictions – Maximum square footage often caps at a percentage of your primary residence
- Parking requirements – Some pilot programs waive new parking mandates
- Permit limits – Certain blocks may restrict the number of ADU permits issued annually
Height restrictions matter too. Coach houses typically max out around 22 feet above grade.
Renovation vs. New Construction
Got an existing structure? Converting a garage or basement usually costs less than building from scratch—assuming the bones are good. Crumbling foundations or extensive structural issues might flip that equation.
New construction demands careful integration with your existing home’s electrical, plumbing, foundation, and roofing systems. The complexity increases, but so does your design freedom.
Cost Breakdown
Let’s talk numbers. ADU construction costs vary dramatically based on your starting point:
- Basic conversions (garage/basement with good bones): $50,000-$120,000
- Full-service ADUs (with kitchen and bathroom): $150,000-$250,000
- New detached construction: $200,000-$350,000+
Factors affecting cost include existing infrastructure proximity, site preparation, architectural design fees, and finish quality. Units without kitchens or bathrooms cost significantly less since plumbing represents a major expense.
