As housing needs evolve, Detached Accessory Dwelling Units (DADUs), also known as backyard cottages, granny flats, or laneway houses, are becoming increasingly popular. These versatile structures provide additional living space while maintaining the charm and integrity of residential neighborhoods. In this comprehensive guide, we delve into “What Is a Detached Accessory Dwelling Unit,” the essentials of DADUs, including their design, regulations, benefits, and how to get started on your project.
What Is a Detached Dwelling?

A detached dwelling is a standalone residential structure separate from the primary residence on the same property. Unlike duplexes or townhomes, detached dwellings do not share walls or structural components with other units. DADUs fall into this category as they are designed to be independent yet secondary to the main home.
Examples of detached dwellings include garden suites, carriage houses, and accessory dwelling units (ADUs) designed for residential use. These structures typically include amenities such as kitchens, bathrooms, and living spaces, making them suitable for long-term habitation.
General Standards for DADUs/ADUs
To ensure DADUs integrate seamlessly into existing neighborhoods, most jurisdictions impose specific guidelines. Common requirements include:
Primary Use
The main dwelling on the property must remain a single-family detached home.
One Per Lot
Only one DADU is allowed per residential lot.
Size Limits
DADUs are generally restricted to a maximum size:
65 square meters (700 square feet) in some municipalities.
800 square feet or 75% of the main residence’s size in others, whichever is smaller.
Owner Occupancy
Property owners are typically required to live on-site, either in the primary residence or the DADU.
Location and Placement
DADUs must adhere to specific placement rules to minimize their impact on neighboring properties and maintain aesthetic standards. These include:
Rear Yard Placement
Many municipalities only permit DADUs to be built in the rear yard of the property.
Setbacks
Side and Rear Setbacks: Minimum of 5 feet from the property lines.
Front Setback: The DADU must be at least 10 feet behind the primary home’s front façade or at least 40 feet from the front lot line.
Lot Coverage
The total coverage of the lot, including the DADU and other structures, must remain within zoning limits.
Review and Approval Processes
Before constructing a DADU, you must navigate the appropriate review and approval process. This often involves:
Type I Review
This simplified process applies to smaller DADUs (e.g., up to 600 square feet and one story). It requires staff-level approval and is generally faster and less expensive.
Type II Review
For larger or more complex DADUs, this process involves public notification, a comment period, and a decision by the Planning Director. While more detailed, it ensures all aspects of the project meet local codes and standards.
Design Standards
Design standards ensure that DADUs complement the aesthetic of the primary residence and the surrounding neighborhood. Common requirements include:
Architectural Features
A covered porch with a minimum depth of 5 feet.
A recessed entry at least 2 feet from the exterior wall.
Roof eaves projecting at least 12 inches.
Horizontal lap siding measuring 3 to 7 inches wide.
Window trim with a depth of at least 5/8 inch.
Privacy Considerations
Windows must be placed in the upper third of walls within 20 feet of adjacent properties.
Alternatively, a 6-foot visual barrier (e.g., fencing or evergreen shrubs) must be installed to maintain privacy.
Benefits of DADUs
1. Additional Living Space
DADUs offer flexible living arrangements for extended family, guests, or caregivers.
2. Rental Income
Homeowners can generate extra income by renting out a DADU.
3. Increased Property Value
A well-designed DADU can significantly boost the resale value of a property.
4. Affordable Housing Solutions
DADUs provide a cost-effective option for housing in urban areas.
Downsides of DADUs
While DADUs offer numerous benefits, there are some challenges to consider:
Costs
Building a DADU requires a significant financial investment, including construction costs, permits, and potential utility upgrades.
Space Limitations
Strict size regulations may limit design options and functionality.
Approval Delays
Navigating zoning laws and approval processes can be time-consuming.
Maintenance
Like any property, a DADU requires ongoing upkeep, which adds to the homeowner’s responsibilities.
What Does DADU Mean?
A DADU, or Detached Accessory Dwelling Unit, refers to a secondary, standalone living space located on the same lot as a single-family home. Designed to be smaller and incidental to the main house, DADUs provide flexible housing solutions for extended family, rental income, or personal use.
Maximum Size and Height Restrictions
Maximum Size
The allowable size for a DADU varies by jurisdiction. Common limits include:
700 square feet in some municipalities.
800 square feet or 75% of the primary dwelling’s size, whichever is smaller.
Building Height
DADUs are subject to height restrictions based on roof type:
Flat Roof: Measure to the top of the parapet or the highest point of the roof.
Pitched Roof: Measure to the average height of the highest gable.
Stepped or Terraced Roof: Measure to the highest segment.
Typically, DADUs are limited to 15 feet for single-story structures and 25 feet for two-story designs.
Steps for Building a DADU
If you’re ready to add a DADU to your property, here’s how to get started:
Research Local Regulations Review zoning bylaws and DADU guidelines specific to your area.
Consult with Experts Schedule a pre-application meeting with a planner to discuss your proposal.
Develop a Design Work with an architect or designer to create a compliant and functional layout.
Secure Permits Obtain all necessary building permits and approvals.
Begin Construction Hire a trusted construction company to bring your vision to life.
Conclusion
Detached Accessory Dwelling Units are a practical and stylish solution for expanding living space, accommodating family members, or generating rental income. By following local guidelines and working with experienced professionals, you can create a DADU that enhances your property’s value and functionality.
For expert guidance and top-notch Construction Services Elk Grove, contact Result Construction today. Let us help you bring your DADU vision to life with our comprehensive construction solutions tailored to your needs.
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