Swell Contracting
Swell Contracting

ADUs & Home Additions in San Diego

Add real living space, whether a guest unit, rental, or extra room, built to last.

Request a free consultation Written scope before work begins

Licensed · Insured · Bonded · CSLB B #970145

Bright, airy San Diego ADU interior with white-oak floors and navy-and-brass accents, by Swell Contracting

CSLB B licensed

License #970145

Scope before work

Selections, responsibilities, and schedule documented in writing.

Warranty in writing

Workmanship coverage is stated clearly in your agreement.

See the work

The details that make the finished space feel right.

Real project and process photography is labeled as such. Design visualizations show direction only, never claimed client work.

Bright ADU interior with efficient open-plan living
Design visualizationSmall-footprint living without feeling small
Warm modern home interior with coordinated flooring and cabinetry
Design visualizationAn addition designed to belong to the home
Open-plan interior with natural light and white-oak flooring
Design visualizationConsistent materials from old space to new

Have a similar space? Send a few photos and we can tell you what to evaluate before the on-site consultation.

Overview

ADUs & Home Additions in San Diego

We start by understanding your goal, whether rental income, multigenerational living, or more space, then assess feasibility, develop design and scope, handle permitting, and build on a confirmed schedule. You get one accountable contractor for the full project.

  • Detached and attached ADUs plus room additions, designed and built by one licensed team.
  • Guidance through design, permitting, and California ADU requirements so the process is less daunting.
  • Construction that matches your existing home and holds its value over time.

Do you need it?

Signs an ADU or addition is the right move

Adding space pays off when your home no longer fits your life or your plans. These are the signs it's time:

1

You want rental income from your property

A detached or attached ADU can become a long-term rental, a common reason San Diego homeowners build one.

2

You're planning for multigenerational living

Aging parents, adult kids, or a live-in caregiver often call for a separate, self-contained living space.

3

You're simply out of room and don't want to move

When the location is right but the square footage isn't, adding space beats taking on a new mortgage and a move.

4

You have an underused garage or backyard

A garage you don't park in, or unused yard space, is often the easiest path to added living area.

5

You want a home office, guest suite, or flex space

A dedicated room or unit separates work and guests from the main living areas of the house.

Why add space with one licensed team

Design, permit, and build under one company

Detached and attached ADUs plus room additions are designed and built by one licensed team, so you have a single accountable contractor.

Guided through California and local ADU rules

ADU requirements cover size, setbacks, parking, and utilities. We guide you through design and permitting so the project meets the rules before construction starts.

Built to match your existing home

New space is detailed to tie into the look of your house rather than read as an obvious add-on, which protects long-term value.

Real, lasting living space

Whether it's rental income, family living, or more room, the result is durable square footage built to hold its value over time.

Feasibility checked before you commit

We assess your specific lot, including size, setbacks, and local rules, during discovery before committing to a scope.

Make the right call

Detached ADU, garage conversion, or room addition?

All three add usable space, but they differ in cost, privacy, and what your lot allows. A detached ADU is a standalone unit; a garage conversion turns existing structure into living space; a room addition extends the main house. Your goal and lot usually point to one.

A detached ADU fits when…

  • You want a fully separate, private unit for rental or family
  • Your lot has room to meet setbacks for a standalone structure
  • Long-term rental income or independent living is the goal
  • You want the most flexibility in layout and entrance

A garage conversion or room addition fits when…

  • A garage conversion: you have an underused garage and want a lower-disruption path using existing structure
  • A garage conversion: lot space is tight and a standalone unit won't fit the setbacks
  • A room addition: you want to expand the main home itself with a bedroom, suite, or larger living area
  • A room addition: the new space should function as part of the house, not a separate unit

Pro tips before you build

  • Start with a feasibility check. Lot size, setbacks, and local rules decide which options are even on the table before you fall for a design.
  • A garage conversion can be the most cost-effective path because it reuses existing structure, but confirm parking rules for your area first.
  • If rental income is the goal, design the unit's privacy and separate entrance early. It shapes the whole layout.
  • Match rooflines, materials, and finishes to your existing home so the addition reads as original and protects resale value.
  • Map out utility connections early; tying water, sewer, and electrical into a new unit is a real part of the budget and schedule.

What affects your investment

  • Type and size: detached ADU, garage conversion, or room addition
  • Whether you're building new structure or converting existing space
  • Utility connections: water, sewer, electrical, and any panel upgrades
  • Foundation, roofing, and how the new space ties into the existing home
  • Site conditions, setbacks, permitting, and finish level

How it works

A clear path from first call to final walkthrough.

We start by understanding your goal, whether rental income, multigenerational living, or more space, then assess feasibility, develop design and scope, handle permitting, and build on a confirmed schedule. You get one accountable contractor for the full project.

Step 1

Consult & assess

A free on-site visit to understand your goals, space, and conditions before anything is priced.

Step 2

Scope & schedule

A written scope, material selections, and a realistic timeline you approve before work begins.

Step 3

Build & walkthrough

One accountable team executes on the confirmed schedule, then walks the finished result with you.

The Swell Contracting team in San Diego

Family-owned in San Diego since 2004

Know who you're hiring

Licensed, documented, and accountable after the last walkthrough.

Two CSLB licenses

B #970145 and C-15 #1002910, available to verify before you hire us.

Scope in writing

The approved work, materials, and schedule are documented before construction begins.

Written warranty

Workmanship warranty terms are included in your agreement so the coverage is clear.

Exceeded our expectations — the care and attention to detail were outstanding.
Caroline H. · Google Reviews

Planning guidance

What to budget and how long it takes.

Planning range

Scoped to your project

Every adus & home additions is priced to your space, materials, and scope, confirmed in a written quote after a free on-site consultation, never a one-size-fits-all number.

Typical timeline

Confirmed at consultation

Timelines vary with scope, materials, and permitting. Your project manager confirms the schedule before work begins.

FAQ

ADUs & Home Additions, answered.

What's the difference between a detached and attached ADU?

A detached ADU is a separate structure on your lot; an attached ADU connects to or converts part of your existing home (like a garage). Each has different cost, permitting, and design implications. We'll help you choose based on your lot, budget, and goals.

Do you handle ADU permitting and requirements?

Yes. California and local ADU rules cover size, setbacks, parking, and utilities. As a design-build GC, we guide you through design and permitting so the project meets requirements before construction starts.

Can I build an ADU on my San Diego property?

Most San Diego residential lots can accommodate some form of ADU, but feasibility depends on lot size, setbacks, and local rules. We assess your specific property during the discovery and site-visit phase before committing to a scope.

Free on-site consultation

Let's look at your adus & home additions together.

Speak with a licensed San Diego team, share the space and your priorities, then receive a written scope built around the actual project.

What happens next

  1. 01

    Share the space

    Call or text photos with the project address and what you want to change.

  2. 02

    We review the conditions

    We ask the practical questions that affect scope, materials, and sequencing.

  3. 03

    Meet on site

    A free consultation confirms the details before a written proposal is prepared.

CallText project photos