What You Need To Know About California's ADU Laws

California Laws For Building Tiny Homes in Backyards, Rural Locations, and Vacant Lots.

If you are interested in building a tiny home on a permanent foundation, the first thing you are going to need to decide is whether you plan to build it as an accessory dwelling unit (ADU) on a property with another home, or if you are looking to purchase a vacant lot or plot of land to construct a new home.

But before you start planning your design or buying materials, it’s important to understand the laws and restrictions that apply in the area that you are building and what requirements and permits are needed. 

We’ll explain some of the differences in planning when constructing tiny homes on permanent foundations as a backyard ADU, and on vacant lots in both urban and rural areas.

Luckily, as a response to the housing shortage and environmental concerns, California has pushed for more leniency and acceptance towards the construction of tiny homes across the state. Living tiny in California gives tiny dwellers the ability to enjoy the state’s beautiful scenery, warm weather, and diverse culture while also living affordably and sustainably. While many people use tiny homes as a way to live remotely and travel, tiny homes are also becoming more common as permanent living solutions.

Building a Tiny Home as a Backyard ADU

Since the implementation of the state-wide ADU (accessory dwelling unit) laws in January of 2020, it has become even easier to convert garages, sheds, and unused backyard spaces into tiny homes for full-time residential living, rentals, or spare guest housing. While ADU’s are probably the easiest to construct in terms of having the least restrictions, they are only allowed in certain residential zones and must be constructed on a lot with another existing home. Hence the term, "backyard ADU".

Backyard ADU Zoning and Size Requirements

California state law allows for the construction of ADUs in single-family or multi-family residential zones. The minimum and maximum size requirements will vary by each city and county, but state law prohibits local agencies from establishing a maximum size requirement of less than 850 square feet or 1000 square feet for an ADU with more than one bedroom. With that in mind, the ADU may not exceed 50% of the size of the primary dwelling on the property. 

Backyard ADU Site Planning

Despite the changes in California ADU laws, constructing a backyard ADU can be just as complicated as constructing a tiny home on its own lot. You will need to work closely with an engineer and the contractor to make sure that all of the designs are compliant with the local and state code as well as Appendix Q, which applies to tiny homes less than 400 square feet.  Appendix Q is an international code that was adopted by California in 2018. In general, you are not required to have an architect to construct an ADU due to its size, but always check the local laws before starting your plans. 

Most of the permits for new construction are going to require percolation tests and soil reports to determine how the ground will absorb water and the foundation that is needed for your backyard ADU. You may be able to skip some of these tests if they were done recently with the primary dwelling but check with your engineer and local laws first. 

Backyard ADU Utilities and Waste Management

Laws regarding utility hookups for ADU’s are also going to vary by each city and county; however, California state law prohibits charging impact fees for any ADU less than 750 square feet. Impact fees are costs meant to offset any indirect environmental or public costs ensued by the development. If your backyard ADU will be more than 750 square feet, the impact fees are to be determined in proportion to the main dwelling unit on the property.

Water and power meters can be shared with the ADU and the primary dwelling unit unless otherwise noted by the local municipality. If you are planning to rent the ADU, it is best to invest in separate meters. California also has solar panel requirements that apply to newly constructed ADUs.

For most California areas, ADU’s are going to require their own sewage system, and these must be approved by a health officer to be deemed acceptable for the property. In most cases, the ADU must be connected to the sewer line that is located downstream from the property. 

Building a Tiny Home on Vacant Lots in Urban Areas

Because of the current housing crisis in California, vacant lots in urban areas can be very difficult to come by. However, if you get lucky and secure a piece of land to construct your new tiny home, there are several steps you must take before you can actually begin construction. 

Zoning and Size Requirements for an Urban Vacant Lot Tiny Home

To start with, your tiny home must be constructed on a lot that is zoned for single or multi-family residential occupancy. In contrast, the minimum and maximum size for your home is going to vary. For a tiny home, the minimum dwelling regulations are going to vary from 350-400 square feet and will be limited to 40% of the property size.

Most cities will have an interactive map or portal so you can view zoning and land information for the lot you are planning to build on. The city of Los Angeles uses this interactive map. To find zoning maps and information for your area, you can usually find them on city or county government websites under ‘land use,’ ‘land development,’ or ‘housing and planning’ sections.

If you still can’t find the zoning information, utilize the website search bars, perform a google search, or you can contact the area’s department for housing and land use. 

Site Planning for an Urban Vacant Lot Tiny Home

Depending on the size and material of your tiny home, you may not need a licensed architect to design the home. The Consumer’s Guide to Hiring an Architect, created by the California Architects Board, advises that you hire an architect; however, a civil engineer or structural engineer may also be able to complete your site planning. 

A great way to ensure that all your planning needs are met is to work with a tiny home consultant to help you find the resources and information that you need. Consultants can also help you navigate the laws and requirements imposed by the area you plan to live in. TheTinyHomeLady.com offers personalized tiny home consulting as well as a 10-week course with support and information to help begin your tiny home journey.

Utilities and Waste Management for an Urban Vacant Lot Tiny Home

If you purchase a piece of land that already has utility hookups or a foundation, you will simply want to have these tested and inspected to make sure everything is good to go. If your lot does not have existing utilities set up, you may need to have percolation, soil, and grading tests done to determine the type of foundation you will need and where the utility hookups should be placed. California code for public service installation can be found here

Building a Tiny Home in Rural Locations

Rural areas are ideal for people that are looking to live a simplistic lifestyle in a tiny home. Purchasing the land for your home outside of California’s urban areas may be more affordable, but it tends to be a more challenging project compared to building homes in the city. This is mostly due to restrictions and expenses related to zoning, access, and utilities. 

Zoning and Size Requirements For Rural Tiny Homes

Similar to looking for land in the city, you must build your home on land that is zoned for residential use. Other types of zoning may only allow camping on the land temporarily. One challenge with putting housing in rural areas is the scarcity of lots that are zoned for residential use. You can apply to have the zoning codes changed, but this process can be very time consuming and challenging.

The minimum and maximum size requirements are also going to vary, but many rural areas have fewer restrictions on size, and you won’t have to worry as much about homeowner association restrictions or strictly city ordinances. 

Site Planning For Rural Tiny Homes

Site planning will begin with many of the same tests that will be required in the city. Soil tests and inspections will be needed to determine the needs for your foundation, waste system, utilities, and any necessary land grading. These are essential to getting your building permits and ensuring that your home is designed with safety in mind.

A great resource to determine which areas are going to pose the most challenges is the interactive maps made available by the California Department of Conservation. The land assessor may be able to offer more zoning and detailed information on the area in addition to the land and development sections on county websites.

Requirements for site planning vary by each area because California’s weather and geography change throughout the state. For example, Mariposa county requires that your home meets their Climatic and Geographic Design Criteria because of the high elevations and winds found in mountainous areas. It’s important to work closely with your tiny home consultant and the city planning department to ensure that all criteria are met before submitting your applications.

An additional challenge to building on undeveloped land is ensuring that you have appropriate access to your property. If there is not public access to the property, you will either need to construct your own private road or get an easement to use someone else’s private road. An easement is a formal “permission” to use someone else’s property for the purpose of gaining access to yours. 

Utilities and Waste Management For Rural Tiny Homes

Rural areas may also pose a challenge related to utilities and waste management. Many utility companies will only build out so far and will ask you to pay for the remaining cost to bring utilities to your land. The California Energy Commission has maps available to help determine which areas have the best access to electricity and other infrastructure. 

Despite the challenges of finding utility hookups, there are alternatives for rural tiny dwellers. Many rural tiny dwellers rely on solar panels, wells, propane, and septic systems for their needs. Just remember that the regulations will change based on the area, and it’s important to take these things into consideration when creating your site plan. 

How can TinyFest Help?

Building a tiny home on a permanent foundation comes with a plethora of rules, regulations, and requirements. Because of this, it’s important to work closely with your designer and the planning department for the area you intend to live in. A great way to connect with the tiny home community and gather information for your home project is to attend TinyFest events. TinyFest events bring together tiny dwellers, builders, consultants, and construction resources so that you can create your perfect tiny home; wherever that may be. 

Still Lost?

Finding the perfect spot to have your tiny home constructed can be daunting and confusing. If you are still feeling lost on where to start or what steps to take, or this feels like a foreign language, you aren’t alone. Don’t hesitate to reach out for help. Tiny home consultants are an invaluable resource to navigating this process and guiding you through each step along the way. You can also reach out to the  zoning and planning department to answer questions specific to the area. 

Key Takeaways

  • Building a tiny home on a permanent foundation requires close communication and collaboration with the city or county planning department and your designer or engineer. 
  • You must construct your home in an area that is zoned for residential use. 
  • Most laws and requirements are going to vary based on the area and its geography. 
  • Most California jurisdictions will require an entire site plan to apply for building permits.  
  • You can work with a tiny home consultant to help navigate the requirements and laws imposed by the area you are planning to live in. 
  • Attending TinyFest events is a great way to meet other tiny dwellers, as well as gather information and resources to build your perfect tiny home in California. 
Article written by Cardinal Marking

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