Detached ADU San Diego construction on sloped backyard

Detached Studio ADU in San Diego

Detached ADU San Diego: 350 sq. ft. Backyard Studio Build

We built a detached ADU in San Diego to transform an underused, steeply sloped backyard into a livable space. The homeowner wanted a flexible unit that could function as a day-to-day office and also host guests for extended visits. By adding a compact, self-contained studio, they gained both immediate usability and long-term property value.

The project site came with one of the biggest challenges we see in backyard construction across San Diego: steep grade changes combined with limited access. What would normally be a three-week phase stretched into five months, thanks in part to the rainy season arriving at the worst possible time.

Once the ground was leveled and stabilized, progress accelerated. Our team built a 350 sq. ft. studio unit with an open living area, a full kitchen, a spacious bathroom, and plenty of natural light. Despite its compact footprint, the interior feels bright and welcoming, making the most of every square foot.

Scroll down to see the full project gallery, from initial site preparation to the completed detached ADU in San Diego.

Detached ADU San Diego Floor Plan

Some of our favorite features from this detached ADU layout include:

  • 104 sq. ft. deck at the entrance, creating an inviting outdoor living space.

  • Multiple large sliding windows and an entrance French door that flood the interior with natural light.

  • Full-size bathroom with a bidet toilet and a walk-in shower.

  • Fully equipped kitchen with an oven, refrigerator and sink for complete functionality.

Floor Plan of a detached ADU in San Diego

350 sq.ft ADU Highlights

Full Project Gallery

Interior view during finishes installation phase in a backyard transformation project
lowboy dumpster hauling concrete and dirt during grading stages for ADU
backyard excavations ongoing during adu and landscaping project
exterior view of foundation forms for detached ADU
digging during prep stages for 8' retaining wall
Forms for foundation being installed during ADU Construction
Foundation forms for ADU
completed forms ready to pour foundation for a detached ADU in San Diego
retaining wall being constructed during rebar and forms stages
concrete pour for retaining wall footings on a slopped lot
foundation footing and stem walls after concrete pour
sub flooring being installed on a raised foundation
exterior view of a detached adu being framed
framing stages of a detached ADU in San Diego
Interior framing view of a studio ADU
Exterior framing view of a detached ADU
Interior framing view of a studio ADU
Fire separation wall with den-shield sheathing on a detached ADU
completed drywalled interior ready for nailing inspection
completed drywalled interior ready for nailing inspection
bathroom remodel with exposed walls during insulation and wall sheathing phase
ADU wrapped in moisture barrier prior to siding installation
ADU wrapped in moisture barrier prior to siding installation
close up view of hardy cement lap planks installed on a detached adu
close up view of hardy cement lap planks installed on a detached adu
detached backyard adu during siding after hardy cement lap planks installed
8' retaining wall with rock face concrete blocks
Interior view during finishes installation phase in a backyard transformation project
full bathroom in an ADU during final tile installation stages
Backyard overhaul during grading and earthwork phase
Photo during hardscaping & earthwork phase showing the retaining wall being prepped for below grade waterproofing
Photo during hardscaping & earth work featured wood forms where concrete stairs are going to be built
Completed Casita built in a backyard on a slopped lot in San Diego with fully equipped kitchen and bathroom
After photo of complete backyard transformation in San Diego, showcasing a finished 350 sq.ft ADU build, pavers and aluminum railings
Exterior view of a graded backyard as part of a large scale backyard transformation that included a studio adu, large 250 sq.ft trex deck and 600 sq.ft of paved patio
Fully equipped kitchen built for a detached adu in San Diego
interior view of the walk-in shower in an ADU built by YNK Construction
interior view of the walk-in shower in an ADU built by YNK Construction
interior view of the walk-in shower in an ADU built by YNK Construction
interior view of a bathroom in a studio adu
Fully equipped kitchen built for a detached adu in San Diego
Interior view from the entrance of a studio ADU built on a slopped backyard
Interior view from the open floor plan studio ADU built on a slopped backyard
Interior view from the kitchen inside a detached studio ADU built on a slopped backyard
Interior view from the kitchen inside a detached studio ADU built on a slopped backyard
After photo of complete backyard transformation in San Diego, showcasing a finished 350 sq.ft ADU build, pavers and aluminum railings
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Ready to Build Your Own ADU?

This project proves that even a property with steep slopes, tricky grading, or limited access can become one of the most functional and valuable parts of your home. With the right planning, crew, and attention to detail, a challenging lot can be transformed into a high-quality living space.

If you’ve been picturing a detached ADU in San Diego like this in your own backyard, now’s the time to start mapping it out. Our ADU construction services cover everything from grading tricky slopes to handling permits, so your project runs smoothly from start to finish.

For a better idea of what to expect, check out our guide on how long it takes to build an ADU in San Diego