The cost to build a 400 sq ft accessory dwelling unit like the Elm typically ranges from $140,000 to $240,000 in San Diego. Pricing depends on your lot conditions, chosen finishes, and whether it’s a detached new build or garage conversion connected to your primary residence. Despite its compact square footage, the Elm delivers a fully functional single bedroom layout with an efficient living space that feels open and versatile. We provide detailed, itemized estimates to ensure transparency—helping you unlock endless possibilities for your property while making smart, informed decisions.

When building a 400 sq ft accessory dwelling unit (ADU) like the Elm in San Diego, it’s essential to follow local zoning regulations and building codes. Detached ADUs must have minimum 4-foot side and rear setbacks, and adhere to height and maximum size guidelines. ADUs under 750 square feet are exempt from costly impact fees, making them attractive for adding additional living space. Owner-occupancy is waived through December 31, 2024 (except JADUs, which always require it). Parking is typically waived if your property is near public transit or involves a garage conversion. Our team ensures your project is compliant, maximizing your lot’s potential with confidence.

Absolutely! The Elm offers excellent rental opportunities for homeowners looking to maximize their residential properties. With an ideal size of 400 sq ft, this ADU type includes a full kitchen, bathroom, and private entrance—providing tenants complete independence and comfort. Its ADU size suits properties with space or property constraints, offering additional functionality without overwhelming your lot. It’s ideal for long-term tenants (30 days or longer), making the Elm a smart choice to create passive income while enhancing your property’s overall value.

Yes! Despite common property constraints, the Elm’s smart design makes full-time living completely comfortable. Its balanced layout includes a private bedroom for residents, a functional kitchen with modern appliances, in-unit laundry, and a spacious living area that feels open and inviting. Whether for singles, couples, or aging family members, the Elm delivers everything needed for independent living in a compact, efficient footprint.

Pre-designed plans can speed up the permitting process, but they often lack the flexibility needed to fully maximize your property's potential. A custom plan like the Elm is the ideal option for homeowners who want a design tailored to their specific lot, lifestyle, and goals. Custom ADUs can better adapt to building codes, allow for additional features like enhanced storage or upgraded kitchens, and deliver long-term cost savings by avoiding costly modifications later. An additional side benefit of choosing a custom plan is that it ensures a more functional, beautiful living space that fits perfectly with your property’s character and needs.

Building a 400–650 sq ft, 1-bedroom ADU like the Elm typically takes about 9 to 12 months from initial feasibility study through completion. The timeline varies based on factors like zoning laws, architectural drawings approval, and site-specific conditions. With our streamlined, in-house process—including additional services such as permitting management and material selections—we help minimize delays and keep your project on track. By carefully planning around construction costs, we ensure your ADU is delivered efficiently without sacrificing quality or design.

Yes! The Elm is an excellent choice for multigenerational living, whether you're housing aging parents, adult kids, or an adult daughter seeking independent space close to family. Its smart design offers a balance of style and privacy, with thoughtful touches like built-in storage solutions, a bathroom ADU design optimized for comfort and accessibility, and additional safety features if needed. With a blend of functionality and modern aesthetics, the Elm provides adequate space for independent living while keeping loved ones connected. It's a perfect example of maximizing ADU benefits for family flexibility and long-term planning.

The Elm stands out among bedroom dwelling units with its smart, minimalist approach to modern living. Designed within a compact 400 sq ft footprint, it features clearly defined living spaces—including a separate bedroom, private kitchen, dedicated dining area, and open living zone—without sacrificing comfort or style. The Elm also blends seamlessly with a variety of architectural styles, making it an ideal choice for homeowners looking for versatility. Whether you're planning a long-term rental or a guest suite, the Elm delivers a sophisticated, space-efficient solution few 1-bedroom ADUs can match.

Definitely. The Elm’s compact 20′ × 20′ footprint makes it an excellent candidate for garage conversions. We’ll evaluate your existing structure during the feasibility phase to determine what’s possible.

Yes—significantly. A well-designed, permitted ADU increases your home’s resale value, attracts more buyers, and can offer immediate rental income. It’s one of the smartest investments a homeowner can make today.

Yes, a 400-square-foot space is typically considered a tiny house by most building departments and federal government agencies. However, when designed with a smart layout and open-concept design, it can feel far larger than its actual footprint. Many accessory dwelling unit designs—like compact granny flats and backyard cottages—make 400 square feet a comfortable living environment with room for a queen-size bed, full kitchen space, and functional living space. With creative smart storage solutions, additional storage, and a thoughtfully balanced floor layout, a 400-square-foot ADU can feel surprisingly spacious and livable.

A 400-square-foot ADU often resembles a modern studio apartment or a compact one-bedroom design. It typically includes a bedroom for guests or a small master suite, a combined dining nook and living area, a private kitchen, and a full bathroom. Thanks to open-concept layouts and smart space efficiency, these homes often include clever additional space like bedroom wardrobes, ample cabinet space, and even a Bedroom With Deck for outdoor living. Many pre-made plans showcase sleek, modern design and cute curb appeal, blending seamlessly into existing properties while respecting property lines and space constraints.

In a 400-square-foot ADU, the most practical occupancy is one or two people, especially when aiming for a comfortable living environment. With space constraints in mind, designs often feature a spacious bedroom with enough room for a queen-size bed, small seating area, and a functional kitchen space. Studio spaces and compact bedroom dwelling units are best suited for singles, couples, or even aging parents. Some layouts, like the 400-650 SqFt 1 Bedroom designs, maximize livability with balanced functionality and clever efficient storage—proving that even tight spaces can feel welcoming with the right design approach.

Absolutely! A well-designed 400-square-foot ADU is not only livable but highly functional. Thanks to modern design innovations and functional floor plans, these units offer adequate living space for singles or couples. Elements like spacious bedrooms, combined living and dining areas, functional kitchen spaces, and built-in storage solutions create a comfortable living environment even with limited availability of space. Plus, the reduced cost of building and maintaining a smaller unit makes it one of the most budget-friendly options for homeowners seeking additional space or extra living space for family members or tenants.

Homeowners build 400-square-foot ADUs for a variety of smart, practical reasons. These bedroom accessory dwelling units offer affordable options to add additional living space to their primary house without major expansion costs. Many use them as beautiful rental units to generate passive income, as law suites for aging relatives, or as private backyard offices. Thanks to the seamless transition between indoor and outdoor spaces and thoughtful detailed drawings during the construction process, 400-sq-ft ADUs provide a winning mix of impactful construction group planning, cost savings, and enhanced property value. Plus, with our Cost Calculator, homeowners can easily estimate cost factors like permit fees, amounts on design fees, and final build costs—making it easier than ever to turn compact spaces into high-functioning living areas.