A project of the Santa Clara County Planning Collaborative

A project of the Santa Clara County Planning Collaborative

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ADU 101

This site walks you through each part of the ADU process, from gathering initial inspiration and learning what you can build through construction and becoming a landlord or moving in.

You can also use our Process-At-A-Glance resource for an overview of the process and some initial issues to consider as you get started.

本网站将引导您了解 ADU 过程的每个部分,从收集最初的灵感和了解您可以建造什么,到建造、成为房东或搬入新居。

您还可以使用我们的 “流程概览 “资源,了解流程概述以及开始时需要考虑的一些初步问题。

該網站將引導您完成ADU流程的每個部分,從收集最初的靈感到瞭解您可以通過施工建造什麼,成為房東或搬入。

您還可以使用我們的 流程概覽 資源來概述流程以及入門時要考慮的一些初始問題。

Este sitio le guía a través de cada parte del proceso de ADU, desde la búsqueda de inspiración inicial y aprender lo que usted puede construir a través de la construcción y convertirse en un propietario o mudarse.

También puede utilizar nuestro recurso “El proceso de un vistazo ” para obtener una visión general del proceso y algunas cuestiones iniciales que debe tener en cuenta al empezar.

यह साइट आपको एडीयू प्रक्रिया के प्रत्येक भाग के माध्यम से चलती है, प्रारंभिक प्रेरणा इकट्ठा करने और सीखने से कि आप निर्माण के माध्यम से क्या बना सकते हैं और मकान मालिक बन सकते हैं या आगे बढ़ सकते हैं।

आप प्रक्रिया के अवलोकन के लिए हमारे प्रोसेस-एट-ए-ग्लांस संसाधन का भी उपयोग कर सकते हैं और शुरू करते समय विचार करने के लिए कुछ प्रारंभिक मुद्दों पर विचार कर सकते हैं।

Trang web này hướng dẫn bạn qua từng phần của quy trình ADU, từ việc thu thập cảm hứng ban đầu và tìm hiểu những gì bạn có thể xây dựng thông qua xây dựng và trở thành chủ nhà hoặc chuyển đến.

Bạn cũng có thể sử dụng tài nguyên Process-At-A-Glance của chúng tôi để biết tổng quan về quy trình và một số vấn đề ban đầu cần xem xét khi bạn bắt đầu.

Accessory Dwelling Units (ADUs) come in many shapes and sizes but are always a self-contained home that is usually smaller than the main house and legally part of the same property. They must have a kitchen, bathroom, and place to sleep, and typically range from studios under 500 to 1,000-square-foot homes with multiple bedrooms.

Junior Accessory Dwelling Units (JADUs) are within the footprint of your home (or attached garage) and less than 500 square feet. They can share a bathroom with the main home and/or have an efficiency kitchen (generally a sink, smaller appliances, and counter) Construction costs for JADUs are typically much lower. In most cases, the property owner must live on site in either the main home or the JADU.

State law now allows homeowners to have both a JADU and a regular ADU on their property.

附属住宅单元 (ADU) 有多种形状和大小,但都是独立的住宅,通常比主住宅小,在法律上属于同一房产的一部分。 这些房屋必须有厨房、浴室和睡觉的地方,面积一般从 500 平方英尺以下的单间到 1000 平方英尺的多卧室房屋不等。

初级附属住宅单元 (JADU) 位于住宅(或附属车库)的占地面积内,面积小于 500 平方英尺。 它们可以与主住宅共用一个卫生间和/或有一个高效厨房(一般只有一个水槽、较小的电器和台面)。 在大多数情况下,业主必须住在主住宅或 JADU 内。

现在,州法律允许房主在自己的房产上同时拥有一个 JADU 和一个普通的 ADU。

附屬住宅單元 (ADU) 有多種形狀和大小,但始終是一個獨立的房屋,通常比主屋小,並且在法律上屬於同一財產。 他們必須有廚房、浴室和睡覺的地方,通常範圍從 500 平方英尺以下的工作室到 1,000 平方英尺的多間臥室的房屋。

初級附屬住宅單元 (JADU ) 位於您家(或附屬車庫)的佔地面積內,面積小於 500 平方英尺。 他們可以與主屋共用一個浴室和/或有一個高效的廚房(通常是水槽、較小的電器和櫃檯) JADU的建築成本通常要低得多。 在大多數情況下,業主必須住在主屋或JADU的現場。

州法律現在允許房主在其財產上同時擁有JADU和常規ADU。

Las viviendas accesorias (ADU, Accessory Dwelling Units) tienen muchas formas y tamaños, pero siempre son viviendas independientes que suelen ser más pequeñas que la casa principal y legalmente forman parte de la misma propiedad. Deben tener cocina, baño y un lugar donde dormir, y suelen ir desde estudios de menos de 500 a viviendas de 1.000 pies cuadrados con varios dormitorios.

Las unidades de vivienda accesorias menores (JADU) se encuentran dentro de la huella de su casa (o garaje adjunto) y menos de 500 pies cuadrados. Pueden compartir un cuarto de baño con la vivienda principal y/o tener una cocina eficiente (generalmente un fregadero, electrodomésticos más pequeños y una encimera) Los costes de construcción de las JADU suelen ser mucho más bajos. En la mayoría de los casos, el propietario debe vivir en la vivienda principal o en la UJI.

La ley estatal permite ahora a los propietarios tener tanto una JADU como una ADU normal en su propiedad.

入门

The best place to start is with thinking about what you want, understanding your goals and concerns, and looking at other ADUs for inspiration. Once you have some ideas in mind, you can consider your budget and move on to Learning the Rules to figure out what you can build on your property.

You can also use our Process-At-A-Glance resource for an overview of the steps and some initial issues to consider as you get started.

Building an ADU is an investment of time as well as money. Most projects take one to two years to complete. Typically, it takes homeowners one to three months to get started and assemble their team, then one to six months to develop plans, meet with staff, and submit the application. Depending on what permits are required, how many rounds of review are required and how quickly a homeowner and their project team can respond to comments, it will take one to six months to get permits. Construction usually takes six to twelve months.

You’re not required to tell your neighbors about your ADU, but it’s always a good idea to communicate with them early in the process. Your project will run more smoothly if they are kept informed, and they may have great ideas for your project!

If you live in a Neighborhood or Homeowners Association (HOA), talk with your representative or board early in the process. They can’t prevent you from building or renting an ADU, but they may have guidelines you’ll need to know for design and construction. Depending on where you live, staff may ask to see written review from your HOA.

Site-built/Traditional: A traditionally constructed ADU is designed and built specifically to your preferences and property and built on site (“stick-built”). This option allows for a lot of customization and smaller changes to be made throughout the construction process.

Prefabricated/panelized/modular: These ADUs are partially or mostly built in a factory, then shipped to your site to be put together. Sometimes the company will include all services in their fee (“turn-key”), including help with permitting and all on-site construction tasks (e.g., laying the foundation, utility hookups, etc.). Other times you’ll need to hire additional professionals to help.

学习规则

In almost all cases, yes! ADUs and JADUs are allowed in all single-family and mixed-use zones. If residential buildings are allowed, ADUs are almost always allowed too (with limited exceptions for safety, traffic, and water).

Homeowners can convert legally built structures (garage, barn, art studio, etc.) into an ADU. JADUs can be converted from an attached garage (but not detached). If you demolish your garage or other enclosed structure and build an ADU in its place, the ADU can be in the same footprint if it’s the same size and height of the structure it’s replacing. You may need to provide replacement parking; check Local ADU Rules or more details.

If you plan on replacing a detached garage with an ADU, demolition permits, and public notice cannot be required if you have your ADU permit (unless it is in an architecturally and historically significant district). Check with staff for other garage-related policies.

Note that garage conversion ADUs may require significant moisture barriers and other design elements in order to meet building codes.

ADUs and JADUs are allowed in all residential and mixed-use zones, with limited exceptions for safety, traffic, and water.

According to state law, you can build up to an 800 square foot ADU, as long as it is not over 16 feet tall and rear and side setbacks are 4 feet or more. Otherwise, size limits depend on your property and local rules. No room behind or next to your main home? You can build it in your front yard instead.

According to state law, rules about setbacks, lot coverage, and open space requirements cannot restrict you from building an 800 square foot ADU, as long as the ADU has setbacks of at least 4 feet and is not above 16 feet tall. Front setbacks also cannot restrict you from building an 800 square foot ADU, which means an ADU can be in a front yard – but only if rear or side placement isn’t possible.

JADU owners need to live in the primary unit or the JADU – and this may need to be recorded in a deed restriction for the property. You may also be required to live on the property if it includes an ADU. Check Local ADU Rules and talk with staff early to find out. 

Generally, ADUs and JADUs cannot be rented for fewer than 30 days at a time.

Parking is much less of a concern than it used to be. JADUs do not require a parking spot. Check Local ADU Rules and talk with your staff to see if ADUs require parking. No new parking is required if ADU is:

  1. Within ½ mile walking distance to transit (including a ferry);
  2. Within an architecturally or historically significant district;
  3. On-street parking permits are required and not provided to the occupant of the ADU;
  4. Located within one block of car-share access, or
  5. Built as part of a new home.

Check the Local ADU Rules to see what parking may be required. 

\Homeowners can build both an ADU, and JADU on their property. Some cities allow you to build more. Multifamily properties can have multiple ADUs, depending on the type and other details of the project.Contact staff for more information if interested in building ADUs on a multifamily property.

预算与财务

The Santa Clara County ADU Calculator is a great place to start when developing a budget. It provides a rough estimate of costs and income and will help you understand how choices can impact your budget over time. In general, it is helpful to avoid having a fixed budget total in your head as you explore your options.The cost to build an ADU typically ranges from $30,000 for a simple interior conversion JADU, to $400,000+ for a large detached ADU with high-end finishes on a hillside lot. Cost per square foot is a good way to estimate, though this too can vary — a very rough placeholder for you to use is $400-550 per square foot for construction (“hard costs”) and design and fees (“soft costs”), depending on your design and the materials you chose.

See more details about costs – including design, permitting, and construction – in our ADU Guidebook.

Many homeowners use a mix of options to finance their ADU, including savings, funds from family, and/or loans. It is strongly recommended that your financing is in place before construction starts. Be sure to factor in potential rental income since that will help you repay loans. See our Guidebook and Exercises for more details on financing options.

If you have equity in your home, a cash-out refinance or home equity loan/line of credit (HELOC) might work for you. Financing is typically unavailable for homeowners with lower income and insufficient home equity, but as of January 2023, the California Housing Finance Agency (Cal HFA) ADU Program provides a grant of up to $40,000 to qualified homeowners for the reimbursement of ADU pre-development costs, including but not limited to impact fees. To qualify, a homeowner must be low or moderate income. Make sure to check if funds are available and if you qualify.

Adding an ADU will likely affect your property taxes and the resale value of your home. However, your primary house will not be reassessed, and your property taxes will only increase based on the added value of your ADU. For example, if you build an ADU that adds $150,000 to your property value, and your tax rate is 1%, your taxes will increase by 1% x $150,000, or $1,500 per year.

Building a JADU will have a significantly smaller impact on assessed value. In some cases, your taxes will not increase at all. Home sharing will also not increase the assessed value of your home. Generally, garage conversions will not raise your tax bill as much as new construction, but they will also not add as much value.

Each property will require a one-on-one analysis to determine the added value of an ADU, so contact the Santa Clara County Assessor’s Office once you have an idea of your plan. They may be able to provide you with a rough estimate of tax implications.

Adding an ADU may impact your income taxes as well. This can be rather complicated, and it’s best to discuss these with a tax advisor.

Generally no. You may need to record in a deed restriction for the property that the ADU cannot be sold separately from the primary home. Check Local ADU Rules and contact your City to find out what local restrictions apply.

Rental income is a major benefit of having an ADU or JADU on your property – for many people, it provides flexibility in their budget or an opportunity to grow their savings. Generally, you cannot rent your ADU for less than 30 days at a time (e.g., AirBnB, Vrbo). The Santa Clara County ADU Calculator can help you estimate how much rental income could be generated by your new unit.

设计

Most homeowners choose to work with some type of design professional to plan their ADU and help throughout the process. Bringing on a professional early in the process is often key to getting your ADU approved quickly, managed efficiently, and built cost-effectively. Relevant experience and fit will be critical.

There are a variety of types of designer, and they may be an architect, builder, “designer,” design/build, or a modular/prefab company. If you’re hiring a local individual or team, they’ll likely start the process by visiting your home and talking to you about your ideas and goals. If it seems like a good match, they will prepare a proposal detailing their services and fee. Professionals typically charge for an initial consultation or proposal.

Note that if you’re not using a licensed architect to design your ADU, your plans may need to be stamped by a licensed engineer. Check with your City early on.

See our Exercises for a list of questions to ask a potential architect or designer, our Glossary to be clear on terms, and our Guidebook for more details.

Once you have a design established with your architect/designer, it’s a great idea to discuss it with City staff so they can point out any issues before you prepare your application.

Depending on the city, you may be able to schedule an appointment to speak with a planner or walk in to the Planning Counter or Permit Center. For contact information, see the Local ADU Rules and Contacts.

This is also a good time to reach out to utility agencies (water, sewer, gas, etc.) to inquire about their infrastructural requirements and confirm connection and service fees.

Site-built/Traditional: A traditionally constructed ADU is designed and built specifically to your preferences and property and built on site (“stick-built”). This option allows for a lot of customization and smaller changes to be made throughout the construction process.

Prefabricated/panelized/modular: These ADUs are partially or mostly built in a factory, then shipped to your site to be put together. Sometimes the company will include all services in their fee (“turn-key”), including help with permitting and all on-site construction tasks (e.g., laying the foundation, utility hookups, etc.). Other times you’ll need to hire additional professionals to help.

许可

Submitting an application is different in each city. Some have online portals while others ask for multiple sets of paper copies on various sizes of paper. Some cities require one application package, while otherwise require separate processes from the Planning and Building departments. Check with your City to confirm the application process and requirements and for details about permit materials.

Some cities may require homeowners to upsize service and or meters to meet capacity requirements. Check Local ADU Rules and talk with staff to learn more about local requirements for utilities.

In most cases, state law no longer allows cities and counties to comment on pre-existing zoning issues unrelated to the ADU. For example, you should not receive comments about correcting the main house or a fence unrelated to the ADU, unless there is an obvious public safety issue.

建筑

If you are not using a design/build firm, you will need to find a contractor to take over for the construction phase of your ADU.

First, you’ll solicit bids. See our Guidebook for more details on what you want to see in a bid, what other documentation to collect from potential contractors, and what to look for in your bidding candidates. You will want to get at least three bids for comparison.

When you have bids, you can begin selecting your contractor. See our Guidebook for more details on how to compare bids and choose the best option for you.

Before you hire a contractor, make sure to check their license and insurance and when they present you with a contract, review everything carefully. See our Guidebook for more details.

Construction costs for your ADU will vary significantly depending on personal preferences, site conditions, location, and many other factors. Despite what many think, smaller ADUs may cost almost the same as larger ones. Many costs like foundation, kitchen and bathroom work only increase slightly for larger ADUs. Kitchen costs will range from $25,000–$50,000 with each bathroom ranging from $15,000–$25,000.

Type:New construction, both detached and attached, tend to be the most expensive. Garage conversions are not much cheaper than new construction if at all. Conversions of interior space (basement or otherwise) are often the cheapest.

Other factors:

  • Quality of interior finish work and amenities
  • Architectural form and details
  • Extent of utility, structural, mechanical, electrical, and plumbing upgrades required
  • Required site upgrades (sidewalks, sewer and water)
  • Whether sprinklers are required
  • Whether doors and windows meet emergency exit standards
  • Lot complexity (slope, trees, fault lines, etc.)

Traditional construction will take 6-12 months, though this will vary depending on the specifics of the project. Stages of construction include:

  • Site preparation: 1-2 months
  • Foundation: 1 month
  • Walls, roof, doors: 1-2 months
  • Plumbing & electrical: 1-2 months
  • Insulation & drywall: ½-1 month
  • Fixtures & finishes: 1-2 months
  • Final touches: ½-2 months

While your contractor will lead the construction process, you will have the following responsibilities:

  • Keep in touch with your contractor and set up a schedule for checking in.
  • Regularly walk through the construction area to monitor the quality of the work and make sure the work is progressing the way you expect.
  • Be prepared to make decisions about the details—light fixtures, appliances, and other materials—in a timely manner so your contractor can stay on schedule.
  • Follow the contract you agreed to, including any changes as described specifically in a change order form.
  • Although your contractor will usually arrange the required city or utility inspections, it is your responsibility as the property owner to make sure that the inspections are conducted as required.

Site-built/Traditional: A traditionally constructed ADU is designed and built specifically to your preferences and property and built on site (“stick-built”). This option allows for a lot of customization and smaller changes to be made throughout the construction process.

Prefabricated/panelized/modular: These ADUs are partially or mostly built in a factory, then shipped to your site to be put together. Sometimes the company will include all services in their fee (“turn-key”), including help with permitting and all on-site construction tasks (e.g., laying the foundation, utility hookups, etc.). Other times you’ll need to hire additional professionals to help.

入住和租赁

As soon as the final inspection is complete, your ADU is ready for move-in! Make sure utility services are set up, an address is established, and other preparations are in place. See below for more responsibilities of being a landlord.

Renting an ADU comes with many responsibilities, including understanding local and state housing laws, executing a lease, finding and managing a tenant, and maintaining a rental property. It’s important to understand the laws as they may affect things like future rent increases, changing use over time, evicting tenants, and moving family into the unit.

See our Guidebook for resources on understanding rental laws, tenants’ rights, and more, and our Exercises for help with your lease terms.

No. Generally, J/ADUs are not allowed to be rented for less than 30 days. This discourages the listing of ADUs on popular websites like Airbnb and VRBO and promotes them as a means to increase housing stock for the diverse needs of county residents. Some cities may require you to file a deed restriction agreeing that the unit will not be used for short-term rentals.

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