Guide to Building an ADU in Maplewood, NJ
What is an ADU?
An Accessory Dwelling Unit (ADU) is a self-contained living space located on the same property as a primary single-family home. While definitions vary by municipality, Maplewood defines an ADU as an "entirely self-contained portion of a principal, one-family dwelling, or located in an accessory building on the same lot."
Why ADUs?
ADUs have gained popularity as a solution to housing challenges, offering:
Increased housing supply
More affordable housing options
Additional income for homeowners
In late 2020, Maplewood amended its zoning code to permit ADUs in several single-family residential zones: R-1-4, R-1-5, R-1-7, and R-2-4.
ADU Requirements
Definition Criteria
An ADU must:
Be a self-contained living space without shared rooms (except for vestibules, entrances, porches, garages, laundry, and mechanical rooms)
Be owned by the principal home's owner and cannot be sold separately
Contain complete housekeeping facilities for only one family
Size Restrictions
Minimum size: 300 square feet
Maximum size: 800 square feet
Maximum bedrooms: Two
Cannot exceed 40% of the principal house's size
Height Limitations
Maximum height: 16 feet
Typically limited to one story due to height and space constraints
Location Guidelines
Must be above grade (not in basement or cellar)
Can be freestanding or connected to the principal home
Freestanding ADUs enjoy more flexible setback requirements:
As close as 4 feet from the rear property line
Side yard setbacks vary by district (4-9 feet)
Must be at least 10 feet from the principal home to be considered an accessory structure
Design Requirements
Exterior must match the principal home's materials and colors
No street-facing separate entrance
Must include:
Entrance
Kitchen
Bathroom
Bedroom
Closet(s)
Living Area
Garage to ADU Conversion
Converting an existing garage can be a cost-effective ADU solution. In Maplewood, garages are not required, making conversion feasible. Considerations include:
Extending plumbing and electrical services
Maintaining existing zoning non-conformities
Respecting the 800 square foot size limit
Ownership and Occupancy
The homeowner must live on the property (either in the main house or ADU)
Cannot sell the ADU separately from the principal home
Cost Considerations
Construction Costs
Estimated budget: $425 per square foot
An 800 square foot ADU could cost approximately $340,000
Recommend using finishes that match the principal home
For rental purposes, choose low-maintenance materials like quartz and porcelain tile
Potential Income
Rental income varies by neighborhood
Research local rental rates for similar units
Ongoing Expenses
Routine maintenance: $2,000 - $5,000 annually
Increased property taxes (typically lower per square foot than the principal home). Speak with the Maplewood Tax Accessor to confirm the estimated increase.
Updated home insurance to cover rental liabilities. Speak with your insurance provider to confirm if the ADU would be covered under the existing policy.
Evaluating Investment Potential
Calculate the ADU's viability by comparing:
Upfront construction costs
Potential rental income
Ongoing operating expenses
An ADU can be a financially attractive option, especially since the land is already owned, eliminating a significant development cost.
Conclusion
ADUs offer a flexible housing solution with potential financial benefits. Careful planning with a licensed architect, understanding local regulations, and thorough financial analysis are key to a successful ADU project.