Guest Homes (ADU)

ADU Contractor San Diego

Accessory Dwelling Unit Design & Build Services

Considering an ADU, guest house or home addition in the San Diego area? Call SM DesignBuild to bring your ADU vision to life. We can create the design and handle all aspects of the building of your new Accessory Dwelling Unit through our quality San Diego ADU design, build and permitting services.

We make it easy by providing you a single point of contact for all aspects of the creation of your new guest house, Accessory Dwelling Unit or add-on project. We provide architectural and design services and we will work with you all the way through the ADU building process.

For over three decades, homeowners have selected SM DesignBuild for their design and construction needs. Adding extra living space is a great investment for any property owner as it dramatically increases the value of your home. Let SM DesignBuild transform your vision into your custom ADU.

Translating our client’s visions into a built environment with the highest standards of craftsmanship is our goal. The Design/Build process allows for the seamless continuity that begins with our first client meeting and ends only when we hand you the key to complete the project.

San Diego area property owners can now build guest homes or granny flats (also called ADUs or Accessory Dwelling Units) easier than ever with new permit regulations. An ADU will help build the value of your property. Whether you need a new ADU (or guest house) built or have an existing one that needs remodeling, you can depend on SM DesignBuild to deliver professional service when you need an Accessory Dwelling Unit contractor in San Diego.

What is an ADU?

An accessory dwelling is a guesthouse, backyard cottage or apartment that has all of the comforts, rooms, and amenities you would expect in a primary home. It creates flexibility for you and your family. You can provide a home for your parent, your child, an au pair, a caregiver, yourself, or a renter.

The accessory dwelling can be a detached or a remodeled part of your main home such as a bedroom, lower floor, or attic. They can be additions to your home as well, either free-standing or attached to the main residence. Accessory dwellings tend to range from studios that are 450 square feet, a one bedroom of about 650 square feet, two bedrooms that are 1000 -1400 square feet, all the way up to a four bedroom home. A real home by any measure.


An accessory dwelling is usually the smartest investment you can make in your home mainly because you're building on land you already own. Given the high land cost in our area, the dollars you spend building your accessory dwelling can easily double your investment in terms of the new market value of your property!


Build Options

Custom Design

Custom design starts with your goals; we listen closely as we begin the preliminary layouts responsive to your desires but tempered by the zoning and municipal constraints applicable to your property. Our custom design process is explained elsewhere. Click here for review -> Our Design/Build Process but most important to you is that we are with you all the way thru this process ‘till the day we hand you the key to your new custom accessory dwelling! This includes all the ‘technical development’ (land survey, soils evaluation, energy performance modeling, etc.), permit processing (coastal & historic commissions), cost/budget updates along the way, and of course the construction and interior finishes phase.

Semi Custom

Semi-custom can be a more affordable alternative to a complete custom build. We achieve this by using our standard plans adapted to include your special needs or desires. This ‘hybrid’ approach can give you flexibility in your budget and still “gets the job done”.


We make available modular accessory dwellings supplied to us by a select number of designers and fabricators based on their business track record, design and manufacturing capabilities. Standard modular designs can often be modified to offer you some of the benefits of ‘Semi-Custom’.

The two questions most asked by clients interested in modular are;
1) is it cheaper than conventional building? and 2) is the construction as good as ‘hand-made’ building? The question about cost is an interesting one. At first look, modular construction appears close to that of conventional. But take into account the dollars saved by reducing dramatically the delivery timeframe typical to conventional construction, and modular begins to make economic sense. And the modular factory manufacturing process is every bit as precise as field construction.

The delivery timeframe of your modular accessory dwelling is dramatically reduced thru all the phases of the process; design is accelerated since plans are already complete, permitting for modular is a simpler and quicker process in most cases, and the construction phase (delivery/install) is a matter of weeks. In all, these timeframes can save you and your family literally months of disruption and construction inconvenience.

Tiny Home

By their size, Tiny Homes are really ‘close cousins’ to accessory dwellings, and can certainly be installed as an alternative to stick-built or modular. Plus of course the flexibility of trailering the Tiny Home to vacation destinations, etc! Give us a call if your interest lies here and we’ll fill you in more on details and options.



The process begins with you sending us the information requested on our CONTACT page. Just email or text us your name, address, and a sentence or two about your needs and goals. We'll then contact you to coordinate a courtesy No Cost design & budget consultation by phone, or a virtual meeting via Skype or Zoom (your preference). We'll do some initial research in advance of speaking so we can give you a very good idea of:

  • maximum size of your dwelling unit;
  • possible locations on your property
  • permitting challenges if any
  • conceptual project costs.

Our chat is at no cost or obligation to you. So what do you have to lose?


There are three major phases to a project: design, approvals, and construction.


The design phase typically takes 2 to 4 months to design one of our custom accessory dwellings During this phase, we prepare the architectural and structural drawings necessary to get a building permit. We can help you select finishes and appliances or you can handle this yourself.


The approvals phase can take as little as 1 to 2 months in jurisdictions with quick plan check times. The time it takes to get local approvals depends on the planning and building departments’ backlog and staffing resources available. If you are building in highly regulated areas, like those needing coastal commission review, you expect a much longer approval schedule.


Once you receive all of the local approvals needed, the construction phase typically takes 6 to 8 months. The timeframe also depends on the size and complexity of the home, and topography/earthwork and utility requirements We periodically update you on your project schedule , so you are prepared in advance for your move-in date.


INTERESTED IN REDUCING THE ABOVE TIMEFRAMES? - Consider a Modular option as explained above.


Governor Newsom Signs New Housing Bills affecting ADU construction here in California - November 2019

The State of California is finally seeing the value of ADUs, and we couldn't be happier. The California legislature and Governor Newsom have taken huge steps by signing into law several bills to improve access to ADUs, making housing better for both homeowners and renters.

Here are the highlights that affect ADU's:

  • AB 68 by Assemblymember Philip Ting (D-San Francisco) makes major changes to facilitate the development of more ADUs and address barriers to building.
    • Permit approvals must happen within 60 days.
    • You no longer have to replace parking spaces.
    • You are allowed TWO ADUs, making every home a potential triplex!
    • You are allowed a minimum of an 800-square-foot ADU, and larger ADUs may be possible in your community.
  • 881 by Assemblymember Richard Bloom (D-Santa Monica) removes impediments to ADU construction by restricting local jurisdictions’ permitting criteria, clarifying that ADUs must receive streamlined approval if constructed in existing garages, and eliminating local agencies’ ability to require owner-occupancy for five years.

  • SB 13 by Senator Bob Wieckowski (D-Fremont) creates a tiered fee structure which charges ADUs more fairly based on their size and location. The bill also addresses other barriers by lowering the application approval timeframe, creating an avenue to get un-permitted ADUs up to code, and enhancing an enforcement mechanism allowing the state to ensure that localities are following ADU statute.


These are great strides toward fair ADU laws.  Right now we’re monitoring the progress of ‘adaptation’ of the above new regulations in our local communities.   Better legislation means more accessory dwellings, happier homeowners due to increased flexibility in their ADU projects, are more-accessible housing for renters.  

Complimentary Consultation

New homes, home remodels, guest homes (ADUs), and special projects.

Our team has years of experience handling all types of projects. As a design- builder we handle all aspects of your construction project, including, design, architectural services, project management and contractor services. We look forward to bringing your ideas to life. During our consultation, we can discuss your vision for the project and how we can make it come to life.


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