An ADU is an additional dwelling unit that can be attached or detached from the primary dwelling.

The ADU could provide affordable housing options for family members, friends, students, the elderly, in-home health care providers, the disabled, and others.

You may want to consider taking advantage of the change in California State law which made it easier to add a second house, called an Accessory Dwelling Unit (ADU), to your residential zoned property.

Granny flat, in-law suite, accessory dwelling unit (ADU), converted garage, backyard cottage, basement apartment , companion units – accessory dwelling units go by many names, but are always a self-contained home smaller than the main house and legally part of the same property. ADU’s can take many forms and vary in size, but always contain everything someone needs to live, including a kitchen, bathroom and place to sleep. ADU’s typically range from 400 sf to 1200 sf.

Where is an ADU allowed?

An ADU can be located on residentially zoned property that has an existing single-family residence.

Is a Building Permit Required for an ADU?

Yes, you will be required to obtain a Building Permit to ensure that the new house meets all the zoning, building, health & safety codes.

What Size ADU is Allowed? How Big?

An ADU is intended to be secondary in size to the single-family residence. California State Laws says an ADU can be attached to or detached from the primary dwelling and may be up to 50% of the size of the single-family residence, up to a maximum of 1,200 square feet.. Check local ADU regulations as some cities within San Diego County have adopted other requirements.

Why Install an Accessory Dwelling Unit?

People build ADU’s for lots of reasons, but the most common are rental income and/or to house relatives. Having a second unit is a simple and old idea to convert unused space. Second units are a relatively affordable type of construction, because they do not require purchasing land or major new infrastructure.

With rents for a 1 bedroom typically averaging over $1400 / month in many areas of Southern California many people install an ADU to help pay off their primary mortgage or earn extra income.

Can you use extra income or do you have a family member /friend that needs a place to live?

How Much Does it Cost to Install an ADU?

Cost depends on several factors:

ADU size

Accessibility to ADU location

Building Code (Local or Federal)

Local Building department requirements and Fees

USModular offers detached ADU’s starting at $89,000 for the ADU built to Federal Code, Delivery, Foundation, and Utility Connection to cities within Southern California. Permits, fees, grading , utility extensions are all site specific and will be determined once a plan is submitted to local building department

What is an Accessory Dwelling Unit?

An accessory dwelling unit, commonly called a granny flat or in-law suite must exist on a lot that’s zoned single-family. It has its own entrance, separate from the primary house, as well as a kitchen, bathroom and living space. These units can be rented, year-round, and add a lot of value to a property.

Zoning

ADUs must be placed on single-family residentially zoned lots. ADUs are allowed in all residential zones.

In Lemon Grove, companion units can also be permitted in multi-family lots under specific circumstances. They are allowed on lots where the maximum number of dwelling units is two. So, if you have, for example, a lot zoned RM1-1 with two units or less you may be able to add a companion unit. Multi-family can get complicated, so we recommend booking a free appointment with a Lemon Grove ADU expert by calling 888-987-6638 to find out if your lot would qualify.

If your area is in a Coastal Overlay Zone, there may be additional regulations in order to protect our coasts.

Lot size

There is no minimum lot size requirement for an ADU in Lemon Grove. Only ADU unit is allowed per lot.

Min/Max Building Sizes

Your maximum build size differs depending on whether your accessory unit is attached or detached from the primary home.

Attached ADU: The floor area of the ADU should not be more than 50% of the existing residence up to 1,200 square feet. For example, if your existing house in 2,500 sq. ft., the attached ADU cannot exceed 1,200 sq. ft. in size.

Detached ADU: For a detached ADU, the total floor space area of the ADU should not be more than 1,200 square feet, regardless of the size of the primary residence.

The floor area of the ADU should be included when calculating the total floor area of the lot.

Height Restrictions

The maximum height of an ADU is 30 feet.

Parking

Companion units should follow the same parking regulations as the main house. If there is parking access from an alley before, there should still be accessible after building an ADU, unless there is a garage.

There are many options for parking spaces. They may be put within setback areas, covered or uncovered, or use mechanical lifts. The important thing is that they provide safe and efficient vehicle access. The minimum parking requirement is one parking space per ADU, with 0.5 parking spots per bedroom.

Parking is not required if the ADU is:

- 500 square feet or less
- Located within half a mile of transit
- Located in a historical resource area
- Already part of the existing building
- Located in a residential permit parking district
- Located within one block of a car share station
- Located within one block of a bike share station

Setbacks

A setback is a minimum distance a structure must be away from the street, buildings, or other features.

ADU’s may extend into the setbacks if the structure is one story and less than 30 feet in length.

Owner Occupancy

An ADU can’t be sold separately from the main house. The owner does not need to live in the main unit or the ADU. Both structures can be rented.

Rentals

California passed Senate Bill 1069 in an effort to increase the supply of housing to the state. For this reason, any accessory dwelling unit may be used for a long-term rental. ADU’s cannot be rented out for less than 30 consecutive days.

How to Evaluate ROI

Building an accessory dwelling unit, especially if you intend to keep the property for a few years, represents an enormously beneficial opportunity to maximize your property.

By constructing an accessory dwelling unit you are adding additional square footage to the property. So if you can build a unit for $275 a square foot, but the average value of homes in your neighborhood are worth $400 a square foot you are gaining instant equity through the project. Plus, you also now have the added benefit of a flexible space that can be rented or used for family.

Additional notes

Construction of a passageway is not required when building an ADU.
A tree must be planted in the front yard or parkway unless a tree that is at least 15 feet high and wide already exists.
A junior unit is an accessory structure that is contained entirely within the main house. They are exempt from parking regulations, and should have a separate outdoor entry, a connection to the main living area, and should include an efficiency kitchen. They may have their own bathroom or share a bathroom with the main house. The junior unit and the main house must be sold together and the owner must live in either the junior unit or the main house.

USModular, Inc. Accessory Dwelling Unit Services include:

Phase 1:

Review local building department for ADU regulations and requirements
Determine floor area ratio, setbacks, parking, mass transit plan, availability of utilities
ADU submittal requirements
New construction of ADU with Modular or Manufactured Home (HUD)
Develop conceptual budget for Modular, Manufactured (HUD), Site Built or Garage Conversion and/or New construction

Phase 2: Construction Contract

Modular or Manufactured Home (HUD) Construction ADU

Select Floor Plan, Specifications, Decor, Etc.
ADU Submittal and approval through State approved 3^rd party and local jurisdiction
Building the ADU off site while completing all onsite construction necessary to meet local ADU requirements, including, utilities, foundation, install, parking etc.
Coordinate with the local building department for inspections
Obtain Certificate of Occupancy

Cost: Accessory Dwelling Units Starting at price

Modular home ADU on permanent foundation starting at $98,000 See Link for builders specifications: USM Standard ADU Modular Builders Specifications
Manufactured home (HUD) ADU on a permanent foundation starting at $89,495 See Link: USM Standard Manufactured (HUD) ADU Builders Specifications
Price includes: Design, fabrication, delivery, foundation, install, fixtures and finishes to USM specifications : USM Standard ADU Modular Builders Specifications
USM Standard Manufactured (HUD) ADU Builders Specifications

ADU must be approved by local building department and site accessible. Assumes level lot with normal soil conditions. Excluded: Civil engineering, local utility and permits and development fees. Pricing is for the following counties, Los Angeles, San Diego, Orange, Riverside, San Bernardino. Areas outside of this will incur additional costs.

USM Standard ADU Modular Builders Specifications

This information is for reference only and lot specific information will be gathered during Phase 1 Feasibility Study.

USM Standard Manufactured (HUD) ADU Builders Specifications

California ADU links:

Senate Bill 1069: Senate Bill 1069

City of Los Angeles ADU Regs: Los Angeles ADU Regs

FAQ’s About Accessory Dwelling Units aka “ADU’s” & Senate Bill 1069

Are Existing Ordinances Null and Void?

Yes, any local ordinance adopted prior to January 1, 2017 that is not in compliance with the changes to ADU law will be null and void. Until an ordinance is adopted, local governments must apply “state standards” In the absence of a local ordinance complying with ADU law, local review must be limited to “state standards” and cannot include additional requirements such as those in an existing ordinance.

Are Local Governments Required to Adopt an Ordinance?

No, a local government is not required to adopt an ordinance. ADUs built within a jurisdiction that lacks a local ordinance must comply with state standards (See Attachment 4). Adopting an ordinance can occur through different forms such as a new ordinance, amendment to an existing ordinance, separate section or special regulations within the zoning code or integrated into the zoning code by district. However, the ordinance should be established legislatively through a public process and meeting and not through internal administrative actions such as memos or zoning interpretations.

Can a Local Government Preclude ADUs?

No local government cannot preclude ADUs.

Can a Local Government Apply Development Standards and Designate Areas?

Yes, local governments may apply development standards and may designate where ADUs are permitted (GC Sections 65852.2(a)(1)(A) and (B)). However, ADUs within existing structures must be allowed in all single family residential zones. For ADUs that require an addition or a new accessory structure, development standards such as parking, height, lot coverage, lot size and maximum unit size can be established with certain limitations. ADUs can be avoided or allowed through an ancillary and separate discretionary process in areas with health and safety risks such as high fire hazard areas. However, standards and allowable areas must not be designed or applied in a manner that burdens the development of ADUs and should maximize the potential for ADU development. Designating areas where ADUs are allowed should be approached primarily on health and safety issues including water, sewer, traffic flow and public safety. Utilizing approaches such as restrictive overlays, limiting ADUs to larger lot sizes, burdensome lot coverage and setbacks and particularly concentration or distance requirements (e.g., no less than 500 feet between ADUs) may unreasonably restrict the ability of the homeowners to create ADUs, contrary to the intent of the Legislature. Requiring large minimum lot sizes and not allowing smaller lot sizes for ADUs can severely restrict their potential development. For example, large minimum lot sizes for ADUs may constrict capacity throughout most of the community. Minimum lot sizes cannot be applied to ADUs within existing structures and could be considered relative to health and safety concerns such as areas on septic systems. While larger lot sizes might be targeted for various reasons such as ease of compatibility, many tools are available (e.g., maximum unit size, maximum lot coverage, minimum setbacks, architectural and landscape requirements) that allows ADUs to fit well within the built environment.

Can a Local Government Adopt Less Restrictive Requirements?

Yes, ADU law is a minimum requirement and its purpose is to encourage the development of ADUs. Local governments can take a variety of actions beyond the statute that promote ADUs such as reductions in fees, less restrictive parking or unit sizes or amending general plan policies.

Can Local Governments Establish Minimum and Maximum Unit Sizes?

Yes, a local government may establish minimum and maximum unit sizes (GC Section 65852.2(c). However, like all development standards (e.g., height, lot coverage, lot size), unit sizes should not burden the development of ADUs. For example, setting a minimum unit size that substantially increases costs or a maximum unit size that unreasonably restricts opportunities would be inconsistent with the intent of the statute. Typical maximum unit sizes range from 800 square feet to 1,200 square feet. Minimum unit size must at least allow for an efficiency unit as defined in Health and Safety Code Section 17958.1.

ADU law requires local government approval if meeting various requirements (GC Section 65852.2(a)(1)(D)), including unit size requirements. Specifically, attached ADUs shall not exceed 50 percent of the existing living area or 1,200 square feet and detached ADUs shall not exceed 1,200 square feet. A local government may choose a maximum unit size less than 1,200 square feet as long as the requirement is not burdensome on the creation of ADUs.

Can ADUs Exceed General Plan and Zoning Densities?

An ADU is an accessory use for the purposes of calculating allowable density under the general plan and zoning. For example, if a zoning district allows one unit per 7,500 square feet, then an ADU would not be counted as an additional unit. Minimum lot sizes must not be doubled (e.g., 15,000 square feet) to account for an ADU. Further, local governments could elect to allow more than one ADU on a lot. New developments can increase the total number of affordable units in their project plans by integrating ADUs. Aside from increasing the total number of affordable units, integrating ADUs also promotes housing choices within a development. ADUs are constructed at the same time as the primary single‐family unit to ensure the affordable rental unit is available in the housing supply concurrent with the availability of market rate housing.

How Are Fees Charged to ADUs?

All impact fees, including water, sewer, park and traffic fees must be charged in accordance with the Fee Mitigation Act, which requires fees to be proportional to the actual impact (e.g., significantly less than a single family home).

Fees on ADUs, must proportionately account for impact on services based on the size of the ADU or number of plumbing fixtures. For example, a 700 square foot new ADU with one bathroom that results in less landscaping should be charged much less than a 2,000 square foot home with three bathrooms and an entirely new landscaped parcel which must be irrigated. Fees for ADUs should be significantly less and should account for a lesser impact such as lower sewer or traffic impacts.

What Utility Fee Requirements Apply to ADUs?

Cities and counties cannot consider ADUs as new residential uses when calculating connection fees and capacity charges.

Where ADUs are being created within an existing structure (primary or accessory), the city or county cannot require a new or separate utility connections for the ADU and cannot charge any connection fee or capacity charge.

For other ADUs, a local agency may require separate utility connections between the primary dwelling and the ADU, but any connection fee or capacity charge must be proportionate to the impact of the ADU based on either its size or the number of plumbing fixtures.

What Utility Fee Requirements Apply to Non-City and County Service Districts?

All local agencies must charge impact fees in accordance with the Mitigation Fee Act (commencing with Government Code Section 66000), including in particular Section 66013, which requires the connection fees and capacity charges to be proportionate to the burden posed by the ADU. Special districts and non-city and county service districts must account for the lesser impact related to an ADU and should base fees on unit size or number of plumbing fixtures. Providers should consider a proportionate or sliding scale fee structures that address the smaller size and lesser impact of ADUs (e.g., fees per square foot or fees per fixture). Fee waivers or deferrals could be considered to better promote the development of ADUs.

Do Utility Fee Requirements Apply to ADUs within Existing Space?

No, where ADUs are being created within an existing structure (primary or accessory), new or separate utility connections and fees (connection and capacity) must not be required.

Does “Public Transit” Include within One-half Mile of a Bus Stop and Train Station?

Yes, “public transit” may include a bus stop, train station and paratransit if appropriate for the applicant. “Public transit” includes areas where transit is available and can be considered regardless of tighter headways (e.g., 15 minute intervals). Local governments could consider a broader definition of “public transit” such as distance to a bus route.

Can Parking Be Required Where a Car Share Is Available?

No, ADU law does not allow parking to be required when there is a car share located within a block of the ADU. A car share location includes a designated pick up and drop off location. Local governments can measure a block from a pick up and drop off location and can decide to adopt broader distance requirements such as two to three blocks.

Is Off Street Parking Permitted in Setback Areas or through Tandem Parking?

Yes, ADU law deliberately reduces parking requirements. Local governments may make specific findings that tandem parking and parking in setbacks are infeasible based on specific site, regional topographical or fire and life safety conditions or that tandem parking or parking in setbacks is not permitted anywhere else in the jurisdiction. However, these determinations should be applied in a manner that does not unnecessarily restrict the creation of ADUs.

Local governments must provide reasonable accommodation to persons with disabilities to promote equal access housing and comply with fair housing laws and housing element law. The reasonable accommodation procedure must provide exception to zoning and land use regulations which includes an ADU ordinance. Potential exceptions are not limited and may include development standards such as setbacks and parking requirements and permitted uses that further the housing opportunities of individuals with disabilities.

Is Covered Parking Required?

No, off street parking must be permitted through tandem parking on an existing driveway, unless specific findings are made.

Is Replacement Parking Required When the Parking Area for the Primary Structure Is Used for an ADU?

Yes, but only if the local government requires off-street parking to be replaced in which case flexible arrangements such as tandem, including existing driveways and uncovered parking are allowed. Local governments have an opportunity to be flexible and promote ADUs that are being created on existing parking space and can consider not requiring replacement parking.

Are Setbacks Required When an Existing Garage Is Converted to an ADU?

No, setbacks must not be required when a garage is converted or when existing space (e.g., game room or office) above a garage is converted. Rear and side yard setbacks of no more than five feet are required when new space is added above a garage for an ADU. In this case, the setbacks only apply to the added space above the garage, not the existing garage and the ADU can be constructed wholly or partly above the garage, including extending beyond the garage walls.

Also, when a garage, carport or covered parking structure is demolished or where the parking area ceases to exist so an ADU can be created, the replacement parking must be allowed in any “configuration” on the lot, “…including, but not limited to, covered spaces, uncovered spaces, or tandem spaces, or….” Configuration can be applied in a flexible manner to not burden the creation of ADUs. For example, spatial configurations like tandem on existing driveways in setback areas or not requiring excessive distances from the street would be appropriate.

Are ADUs Permitted in Existing Residence or Accessory Space?

Yes, ADUs located in single family residential zones and existing space of a single family residence or accessory structure must be approved regardless of zoning standards (Section 65852.2(a)(1)(B)) for ADUs, including locational requirements (Section 65852.2(a)(1)(A)), subject to usual non-appealable ministerial building permit requirements. For example, ADUs in existing space does not necessitate a zoning clearance and must not be limited to certain zones or areas or subject to height, lot size, lot coverage, unit size, architectural review, landscape or parking requirements. Simply, where a single family residence or accessory structure exists in any single family residential zone, so can an ADU. The purpose is to streamline and expand potential for ADUs where impact is minimal and the existing footprint is not being increased. Zoning requirements are not a basis for denying a ministerial building permit for an ADU, including non-conforming lots or structures. The phrase, “within the existing space” includes areas within a primary home or within an attached or detached accessory structure such as a garage, a carriage house, a pool house, a rear yard studio and similar enclosed structures.

Are Owner Occupants Required?

No, however, a local government can require an applicant to be an owner occupant. The owner may reside in the primary or accessory structure. Local governments can also require the ADU to not be used for short term rentals (terms lesser than 30 days). Both owner occupant use and prohibition on short term rentals can be required on the same property. Local agencies which impose this requirement should require recordation of a deed restriction regarding owner occupancy to comply with GC Section 27281.5

Are Fire Sprinklers Required for ADUs?

Depends, ADUs shall not be required to provide fire sprinklers if they are not or were not required of the primary residence. However, sprinklers can be required for an ADU if required in the primary structure. For example, if the primary residence has sprinklers as a result of an existing ordinance, then sprinklers could be required in the ADU. Alternative methods for fire protection could be provided.

If the ADU is detached from the main structure or new space above a detached garage, applicants can be encouraged to contact the local fire jurisdiction for information regarding fire sprinklers. Since ADUs are a unique opportunity to address a variety of housing needs and provide affordable housing options for family members, students, the elderly, in-home health care providers, the disabled, and others, the fire departments want to ensure the safety of these populations as well as the safety of those living in the primary structure. Fire Departments can help educate property owners on the benefits of sprinklers, potential resources and how they can be installed cost effectively. For example, insurance rates are typically 5 to 10 percent lower where the unit is sprinklered. Finally, other methods exist to provide additional fire protection. Some options may include additional exits, emergency escape and rescue openings, 1 hour or greater fire-rated assemblies, roofing materials and setbacks from property lines or other structures.

Is Manufactured Housing (HUD) Permitted as an ADU?

Yes, an ADU is any residential dwelling unit with independent facilities and permanent provisions for living, sleeping, eating, cooking and sanitation. An ADU includes an efficiency unit (Health and Safety Code Section 17958.1) and a manufactured home (Health and Safety Code Section 18007).

Health and Safety Code Section 18007(a) “Manufactured home,” for the purposes of this part, means a structure that was constructed on or after June 15, 1976, is transportable in one or more sections, is eight body feet or more in width, or 40 body feet or more in length, in the traveling mode, or, when erected on site, is 320 or more square feet, is built on a permanent chassis and designed to be used as a single- family dwelling with or without a foundation when connected to the required utilities, and includes the plumbing, heating, air conditioning, and electrical systems contained therein. “Manufactured home” includes any structure that meets all the requirements of this paragraph except the size requirements and with respect to which the manufacturer voluntarily files a certification and complies with the standards established under the National Manufactured Housing Construction and Safety Act of 1974 (42 U.S.C., Sec. 5401, and following).

Can an Efficiency Unit Be Smaller than 220 Square Feet?

Yes, an efficiency unit for occupancy by no more than two persons, by statute (Health and Safety Code Section 17958.1), can have a minimum floor area of 150 square feet and can also have partial kitchen or bathroom facilities, as specified by ordinance or can have the same meaning specified in the Uniform Building Code, referenced in the Title 24 of the California Code of Regulations.

The 2015 International Residential Code adopted by reference into the 2016 California Residential Code (CRC) allows residential dwelling units to be built considerably smaller than an Efficiency Dwelling Unit (EDU). Prior to this code change an EDU was required to have a minimum floor area not less than 220 sq. ft unless modified by local ordinance in accordance with the California Health and Safety Code which could allow an EDU to be built no less than 150 sq. ft. For more information, see HCD’s Information Bulletin at hcd.ca.gov

Does ADU Law Apply to Charter Cities and Counties?

Yes. ADU law explicitly applies to “local agencies” which are defined as a city, county, or city and county whether general law or chartered (Section 65852.2(i)(2)).

Do ADU’s Count Towards the Regional Housing Need Allocation?

Yes, local governments may report ADUs as progress toward Regional Housing Need Allocation pursuant to Government Code Section 65400 based on the actual or anticipated affordability. See below frequently asked questions for JADUs for additional discussion.

Must ADU Ordinances Be Submitted to the Department of Housing and Community Development?

Yes, ADU ordinances must be submitted to the State Department of Housing and Community Development within 60 days after adoption, including amendments to existing ordinances. However, upon submittal, the ordinance is not subject to a Department review and findings process similar to housing element law (GC Section 65585)

San Diego County (unincorporated) ADU Regulations Accessory Dwelling Unit Regulations

Link to Companion Unit Handbook:

https://www.sandiego.gov/sites/default/files/2019-companion-unit-handbook.pdf

Update: San Diego County recently passed a fee waiver that will save homeowners an average of 14K on permitting fees

San Diego County Passes Granny Flat Fee Waiver

San Diego County just took major steps to promote the building of accessory dwelling units, commonly called granny flats. They passed a fee waiver saving homeowners an average of $14,000 on permit costs. This waiver will only be in effect till 2023 so act quickly to take advantage of this.

This fee waiver may mean it’s much more feasible for you to build!

Affordable housing advocates hope this will spur ADU development in San Diego County where rental prices have soared and vacancy rates hover at just 3.3%.

California passed Senate Bill 1069 in January of 2017 stating that any single-family home could build a second rentable unit. In major cities across California, accessory dwelling unit permit applications spiked in a reaction to the passage of the bill.

San Diego County, until recently, was still charging Development Impact Fees of close to $14,000. (San Diego passed a major fee waiver in July of 2018 and has since seen a large uptick in permit applications.)

So if you’ve been on the fence about starting a project, now is a fantastic time!

Lot size

There is no minimum or maximum lot size requirement to build an accessory dwelling unit.

Min/Max Building Sizes

Detached ADU: For a detached ADU, the total floor space area of the ADU should not be more than 1,200 square feet, regardless of the size of the primary residence.

Height Restrictions

ADU’s are limited to 24 feet in height.

Parking

Detached ADU’s are required to have one parking space per bedroom or unit. Off street parking is allowed to be tandem or within the residence’s setbacks given that it is safe to access. If the ADU’s construction involves a conversion, replacement off street parking must be provided.

Parking not required if the ADU is:

Located within ½ mile of public transit
Located within an architecturally and historically significant historic district
Part of an existing primary residence or an existing accessory structure
In an area where on-street parking permits are required, but not offered to the occupant of the ADU
Is located within one block of a car share area, attached ADU’s built within the existing residence do not require additional parking. This part can get tricky, so we recommend booking a free appointment with a Lemon Grove ADU expert to find out what your lot needs.

Setbacks

A setback is the minimum distance a structure must be away from the street, buildings, or other features.

Two-story ADU’s are required to have a setback of five feet from the side and rear lot lines.

Attached ADU’s must follow the setback regulations of the main residence.

Rentals

California passed Senate Bill 1069 in an effort to increase the supply of housing to the state. For this reason, any accessory dwelling unit may be used for a long-term rental. No short term rentals (less than 30 days) are allowed.

How to Evaluate ROI

Building an accessory dwelling unit, especially if you intend to keep the property for a few years, represents an enormously beneficial opportunity to maximize your property.