San Diego ADU build process showing plans, framing, construction, and finished living space.
ADU Building calendar_today May 06, 2026 schedule 11 min read

What to Expect During a San Diego ADU Build: From First Call to Final Inspection

San Diego ADU build process showing plans, framing, construction, and finished living space.

Building an ADU is exciting, but it can also feel intimidating if you have never been through a construction project before. Homeowners usually have the same questions: How does the process start? When do plans happen? What does permitting involve? How disruptive is construction? What decisions do we need to make? How do we avoid surprises?

A good builder should be able to explain the process clearly before work begins.

This guide walks through what to expect during a San Diego ADU build process, from the first conversation to final inspection. The exact timeline and scope will vary by property, but the overall path is similar: goals, feasibility, design, permits, preconstruction, construction, inspections, and turnover.

Step 1: The First Conversation

The first call is not just about square footage. It is about understanding why you want to build.

CRS Builders Inc. will want to understand:

This first conversation helps determine whether the project is likely to be a good fit and what information is needed next.

Step 2: Property Feasibility Review

Before a design is finalized, the property needs to be evaluated. ADU feasibility is one of the most important phases because it helps prevent bad assumptions.

A feasibility review may consider:

This is where the project may become more specific. A homeowner may start with a detached ADU idea, but a garage conversion or JADU may fit the property better. Another homeowner may assume the garage is the best option, but a detached ADU may provide better long-term function.

Step 3: Scope Alignment

Scope alignment means matching the homeowner’s goals to the property, design direction, and investment level.

This is where CRS Builders Inc. helps clarify what kind of project is actually being discussed. A compact JADU, a garage conversion, a custom detached ADU, and an attached ADU are not the same scope. They have different design requirements, construction needs, permit considerations, and finish expectations.

A quality builder should help you understand:

CRS currently builds in a quality-focused context where project scope can land around $400–$750 per square foot, depending on site conditions, finishes, utility work, structural complexity, and project type. The goal of scope alignment is not to chase the lowest number. It is to make sure the plan, expectations, and investment level match before construction begins.

Step 4: Design Direction and Layout

Once feasibility and scope are understood, design can move forward with more confidence.

Design decisions include:

This is the phase where the ADU starts to become real. But the best designs are still grounded in practical constraints: utilities, structure, access, setbacks, drainage, and budget.

A beautiful design that ignores construction reality is not helpful. A strong ADU design balances livability, code, buildability, and long-term value.

Step 5: Plans, Engineering, and Documentation

After the layout direction is established, the project moves into construction documents and technical coordination.

Depending on the project, this may involve:

San Diego requires Building Permits for ADUs and JADUs. If the property has special conditions such as coastal overlay, fire hazard, slope, or brush management considerations, documentation may require additional care.

This phase is not always glamorous, but it is essential. Good documentation helps the project move through permitting and gives the construction team a clearer path.

Step 6: Permit Submittal and City Review

Once the documents are ready, the project is submitted for permit review.

The City review process may involve comments, corrections, or requests for clarification. That is normal. The important thing is having a team that can respond clearly and keep the project moving.

Permit timing can vary based on:

CRS Builders Inc. helps homeowners understand that permitting is part of the project timeline. It should be planned for, not treated as a surprise.

Step 7: Preconstruction Planning

After permit approval, the project moves into preconstruction. This is the bridge between paperwork and building.

Preconstruction may include:

This phase helps reduce confusion once crews are on site. The more decisions are clarified before construction starts, the smoother the build can be.

Step 8: Site Preparation

Construction begins with preparing the area.

Site preparation may include:

For garage conversions, site preparation may involve selective demolition, removing the garage door, opening walls, evaluating the slab, and preparing for new utilities or framing.

For detached ADUs, site preparation may involve grading, foundation prep, utility trenching, and material staging.

Step 9: Foundation, Framing, and Structural Work

For a detached ADU or addition, the foundation and framing phases are where the project visibly takes shape.

This phase may include:

For garage conversions and JADUs, structural work may be different. Instead of a new foundation and full frame, the work may involve modifying existing framing, infilling openings, reinforcing walls, or creating new entries.

This is one reason project type matters. Different ADU paths have very different construction realities.

Step 10: Rough Plumbing, Electrical, and Mechanical

After framing, the major systems are installed.

Rough-in work may include:

This phase is where good planning pays off. If the kitchen, bathroom, laundry, and mechanical systems were coordinated early, rough-in work is more straightforward.

Step 11: Insulation, Drywall, and Interior Buildout

Once rough systems pass required inspections, the ADU starts to feel like an interior space.

This phase includes:

For homeowners, this is often the most exciting part because the design choices become visible. It is also where durability matters. ADUs are small spaces that get daily use, so finishes should be selected for both appearance and longevity.

Step 12: Exterior Work and Site Finish

Exterior work may happen throughout the project, but final site finish brings everything together.

This can include:

The exterior should make the ADU feel integrated with the property. A well-built ADU should not look like a temporary unit dropped into the backyard. It should feel intentional.

Step 13: Inspections and Final Walkthrough

Throughout construction, inspections confirm that work is being completed according to approved plans and applicable codes.

Final steps may include:

The final walkthrough is the homeowner’s opportunity to understand the completed space, review details, and confirm remaining punch-list items if any.

How Homeowners Can Help the Process Go Smoothly

A good builder manages the project, but homeowners also play an important role.

You can help by:

The smoother the communication, the better the experience.

Common ADU Process Mistakes to Avoid

Starting With a Plan Before Feasibility

A floor plan is only useful if it fits the property. Feasibility should come first.

Underestimating Permitting

Permitting is not a side task. It is a real phase of the project and should be included in the timeline.

Making Finish Decisions Too Late

Late selections can slow ordering and scheduling. Decide key finishes before they become urgent.

Ignoring Utility Complexity

Electrical, sewer, water, and HVAC decisions affect design and construction. They should be evaluated early.

Choosing Based Only on Price

The lowest number does not always produce the best project. Scope, quality, communication, and experience matter.

Frequently Asked Questions About the San Diego ADU Build Process

How long does it take to build an ADU in San Diego?

The full timeline depends on design, permitting, site conditions, project type, and construction scope. Homeowners should think in phases: feasibility, design, permit review, preconstruction, construction, inspections, and turnover.

What happens first when I contact CRS Builders Inc.?

The first step is a conversation about your goals, property, desired use, timeline, and project type. From there, CRS can help determine whether feasibility review, design planning, or another next step makes sense.

Do I need plans before calling a builder?

No. In many cases, it is better to speak with a builder before investing heavily in plans. A feasibility review can help make sure the design direction fits the property and construction reality.

What causes ADU delays?

Common delays include incomplete plans, permit comments, late selections, utility surprises, site access issues, scope changes, and special conditions such as coastal or fire-zone requirements.

Can CRS Builders handle garage conversions and JADUs too?

Yes. CRS Builders Inc. works on ADUs, JADUs, garage conversions, home additions, and new custom homes. The best path depends on the property and goals.

How should I budget for a quality ADU?

Budget should be based on scope, site conditions, design, utilities, structural needs, finish level, and permitting requirements. CRS currently builds in a quality-focused context where project scope can fall around $400–$750 per square foot depending on the details.

Ready to Understand the ADU Process for Your Property?

A successful ADU is not just a finished structure. It is the result of good planning, clear scope, strong communication, quality construction, and a process that respects the property.

Thinking about building an ADU in San Diego? Call CRS Builders Inc. at 858-788-3839 or visit crsbuildersinc.com to schedule a consultation.

CRS Builders Inc. helps San Diego homeowners plan and build ADUs, JADUs, garage conversions, additions, and new custom homes.

Ready to talk through your options?

Schedule a property-specific consultation with CRS Builders Inc. in San Diego County.

Get a Free Estimate arrow_forward

Related Articles

ADU Building

San Diego ADU Feasibility Checklist

Read more arrow_forward ADU Design

Design an ADU That Feels Like a Real Home

Read more arrow_forward
View All Articles arrow_forward