Tiny Home Living

Accessory Dwelling Units California

Aka Granny Flat

Welcome to USModular Home Builders, Southern California’s premier full service design and build general contractor   for the construction of your Accessory Dwelling Unit (ADU). We have built hundreds of units across Southern California using prefabricated construction and are experienced and knowledgeable in dealing with all aspects of the building process.

With 75 combined years in general contracting and real estate development we learned a few things along the way.

We handle all aspects of your project from initial site visit, to creation of budget/contract through permits and construction, utility connections and finally handing you a set of keys for your new ADU…all with minimal disruption to residents of primary dwelling unit as the ADU is set into your backyard in ONE DAY!!!!!

What is an ADU?

An accessory dwelling unit-aka granny flat-aka companion unit is a second small dwelling on the same parcel of land as your single-family house.  An ADU can be up to 1,200 sq ft and can be built as:

  • Detached stand alone building
  • Attached to primary dwelling
  • Converted garage
  • Converted space within the primary dwelling (Junior ADU)

Why Build an ADU?

  • Additional Space for family members – grandparents, kids , relatives

We recently built an ADU for family in Orange County. It was built for the homeowners Mom, who was living in a 1 bedroom apartment – 10 miles from family and they were spending $1,500 a month on rent.  Grandma moved into The Bungalow ADU and is now closer to her daughter and grandkids.  She feels safer, and has more social connections with family.   The family has a net savings over $1000 month in rent. A true ADU success story.

  • Rental Income – turn a single family rental property into a 2 income property.

An Investor with a single family income property in San Diego put it best when he asked us – “where can I buy a 2 bedroom rental property for under $120,000 in San Diego?   Nowhere!   But I can build a 2 bedroom ADU for this price – it’s a no brainer”

How much does it Cost to build an ADU?

There are many local and site specific factors to determine the complete cost to build an ADU Including access to the back yard, topography, utility location, sewer or septic, local fees including sewer capacity fee, school fees, permits etc.  But we have created the cost to build an ADU that assumes we have access to backyard on a level lot and sewer is available within 100 ‘ of house.  Starting cost for our 398 sq ft 1 bedroom ADU (Federal Building Code) is $78,000 which includes the ADU, transportation to site, roll set/ installation on permanent foundation, connection to utilities.  The local fees are city or county specific and typically range from 5-15% of the quoted construction cost.

New 2020 California Laws:

ADUs are less expensive, faster and easier to build!!!

California is in a housing crisis – both of physical houses and affordability. ADUs help the crisis  by getting more homes and lowering cost to build as land and utility infrastructure is already in place (2 of the biggest costs to build a new home). New State of California ADU laws include:

  • ADUs can be up to 1,200 sq. ft. regardless of the size of primary dwelling unit (as long as you meet setbacks and FAR)
  • Setbacks reduced to 4’ side and rear yard
  • Parking requirement for ADU waived
  • No owner occupancy of primary dwelling unit (great for investors)
  • 60 day review process by local building department
  • Waiver of local development fees for ADUs less than 750 sq. ft.
  • Multifamily homes eligible for ADU
  • Fire Sprinklers ONLY required if Primary Dwelling Unit has them in place

Why build an ADU with prefabricated construction?

This is a question we get asked daily.  For us it’s a pretty easy answer – because we can build better, faster, greener and for less in our factory than a site built ADU. Same reason that we drive cars built in a factory – they have a more precise process building on a production line, indoors,  by a team of workers that work in sync …than assembled  in your back yard.  Another important reason to consider prefabricated is the site construction is site construction time – as site built projects will take months of daily hammering, sawing, dumpsters, and port-o-potties with 10+ different workers walking into backyard to this time period.  With prefabricated construction – the ADU is built in a factory – we set unit in backyard in ONE DAY.  Once set we have a very small crew- to do finish work and utility connections.

How long will it take to build an ADU?

A lot depends on you. How long you take to choose style, code and floor plan will determine length of project.  Once the ADU plan is chosen and contract is signed – typically time from is 5-8 months to get permit and build a project.  Much of this time is spent on the State and Local approval of the building plans.  Once we have permit in hand – the USModular team will act very fast and typically can complete a project within 2-3 months.

What is process to build an ADU with USModular?

Phase 1:  Planning

  • Site visit to determine setbacks, accessibility , utility location /availability, FAR
  • ADU submittal requirements
  • New construction of ADU with Modular (CBC/Local) or Manufactured (HUD/Federal))
  • Develop conceptual budget for ADU and site construction

Phase 2:  Construction Contract

  • Finalize construction budget and contract

Phase 3: Plan Design and Submittal

  • Site plan design
  • ADU approval through State approved 3rdparty and local jurisdiction
  • Build (Fabrication) the ADU at Factory while prepping onsite construction necessary to meet local ADU requirements, including, utilities, foundation
  • Coordinate with the local building department for inspections

Phase 4:  Final Inspection

  • Walk through ADU with client make adjustments as needed
  • Obtain Certificate of Occupancy

How do we start?

We thought you would never ask!!!!

Review the series of floor plans that we offer:

  • Custom Cottage   – Affordable, Federal Building Code
  • California Series – Mid Range – Federal and Local Building Code – More flexibility
  • California Dreaming  – Modern/Contemporary plans – Cool look for modern homes

Email info@usmodularinc.com or call us 951-679-9907 to discuss your project.  If you want to proceed we can schedule a site visit to further review the project.

List of California City / County ADU Requirements

Here is a list of California City and County ADU regulations specific for each area.

Alison Viejo
Beverly Hills
Cathedral City
Chula Vista
Costa Mesa
Culver City
Del Mar
Desert Hot Springs
Diamond Bar
East Palo Alto
El Cajon
El Segundo
Fountain Valley
Garden Grove
Huntington Beach
Jurupa Valley
La Habra
La Mesa
La Quinta
Lake Elsinore
Lemon Grove
Long Beach
Los Angeles
Los Angeles County
Monterey Park
Moreno Valley
National City
Orange County
Palm Desert
Palm Springs
Rancho Cucamonga
Rancho Mirage
San Bernardino
San Clemente
San Diego (City)
San Diego (County)
San Gabriel
San Jacinto
San Marcos
Santa Ana
Santa Clarita
Simi Valley
Thousand Oaks
Thousand Palms
West Covina
Yorba Linda