Building an accessory dwelling unit involves more than choosing a floor plan. The strongest projects begin by understanding the property, local rules, project goals, utilities, budget, and construction requirements before committing to a design.
1. Decide what the ADU needs to accomplish
Start with the reason you want an ADU. The intended use influences almost every decision that follows, including size, bedroom count, accessibility, privacy, parking, storage, and layout.
Long-term rental income
Housing for aging parents
Guest accommodations
Independent living for family
Downsizing
Home office or flexible living space
2. Understand your property
A great ADU plan on the wrong property is still the wrong plan. Before narrowing designs, understand the physical constraints of the parcel.
Lot dimensions
Existing house location
Available backyard or side-yard space
Setbacks
Easements
Driveway access
Topography
Septic or sewer availability
Water service
Utility locations
3. Check state and local ADU rules
ADU requirements can vary significantly between states, cities, counties, zoning districts, and individual properties.
Before purchasing plans, verify that an ADU is allowed and identify any known limits involving size, height, location, parking, bedrooms, lot coverage, owner occupancy, or utility connections.
4. Establish your buildable footprint
Once you understand the property and applicable zoning standards, estimate the area where an ADU could realistically fit.
This helps prevent falling in love with a 28-foot-wide plan when the site only has room for a 20-foot-wide structure.
5. Choose the right plan
Now you can compare plans based on more than appearance. Look at width, depth, square footage, stories, bedroom count, accessibility, structure type, and how the layout supports your intended use.
6. Decide whether modifications are needed
Stock plans are a strong starting point, but the site or lifestyle may require changes. Common modifications include moving windows, resizing rooms, adjusting dimensions, changing exterior details, or improving accessibility.
7. Confirm local construction requirements
Stock architectural plans may still require local engineering, site plans, energy documentation, septic approvals, utility coordination, or jurisdiction-specific revisions before permits can be issued.
8. Move into permitting and construction
Once the design, property, and local requirements align, the project can move into permitting, contractor pricing, site preparation, and construction.
Project requirements vary.
Best ADU Plans provides general educational information. Zoning, building codes, engineering, permitting, utilities, and property conditions should be verified for the specific project and jurisdiction.