Missing details on your ADU permit site plan can stall an application for weeks. Building departments use the drawing to check setbacks, access, and lot coverage before approving the next step. Getting the layout right the first time helps keep your project on schedule.
Order a detailed site plan for your ADU permit application.
An ADU permit is a legal requirement in most cities because these units are living spaces that must meet safety codes and local zoning laws for your land. According to the City of San Jose, you must get building, zoning, and trade permits for plumbing or power work before any building starts on your own property. The review process usually takes 30 to 60 days, during which time city officials use your site plan to verify the unit follows all height and setback rules. Complete site plans help reduce avoidable review comments and keep the city review moving so you can reach the next project step sooner.
What does an ADU permit site plan need to show?
Getting an adu permit starts with a clear map of your land. This map, or site plan, shows the city how your project fits on the lot. Most cities require these plans for accessory dwelling units because they see an ADU as a living space. The City of San Diego says an ADU must provide full living facilities for one or more people. The site plan proves that your new unit meets local rules for safety and size.
Property lines and existing buildings
The first part of your site plan focuses on the ground you already own. You must show the exact lines of your property. This helps the city show that you are building on your own land and not crossing into a neighbor's yard. You also need to show the main house and any other buildings, like sheds or garages, that are already there. Adding these items allows staff to check your total lot coverage. Most areas have strict limits on how much of a lot can be covered by roofs or concrete.
You also need to mark the setbacks on your plan. Setbacks are the least space needed between a building and the property line. These rules keep homes from being too close to each other or the street. If you are changing a garage, you should check specific ADU permit requirements for your town. Some cities allow smaller setbacks for garage projects than for new detached units. Marking these gaps clearly helps avoid delays during the review phase.
New unit size and location
The site plan must show clearly where the new ADU will go. This includes the footprint, which is the total area the unit takes up on the ground. You should include the length and width of the structure. City staff use this data to ensure the unit stays within size limits. Many cities cap the size of an ADU at 800 to 1,200 square feet. The plan must also show the height of the new building. Many cities set height limits to keep the ADU from blocking a neighbor's view or sun.
Your plan should also show how the ADU relates to the main house. It needs to show the space between the two buildings. This is often a safety rule for fire trucks or rescue workers to reach the back of the lot. If your ADU is attached to the main home, the plan must show just where they connect. These details help the building department see the full scale of your project before they give a permit.
Utility lines and property access
Access is a major part of the permit review. You must show how people will get to the ADU from the street. This includes any new paths or driveways. Cities also look for parking details. While some laws now waive parking rules for ADUs near transit, you still need to show any existing parking spots. The plan should also note where your utilities go. This includes lines for water, gas, and sewer. Most cities want to see if the ADU will share a meter with the main house or have its own.
- Property lines and easements
- Existing home and proposed ADU footprint
- Space between buildings and property lines
- New and existing paths or driveways
- Spots for water and sewer lines
Giving a full site plan cuts the risk of a no from the city. If you build without a permit, you may face big fines or have to tear the unit down. The City of San Jose warns that building without a permit can lead to legal issues. A good plan makes the process faster and helps you get to the building stage sooner. Most city reviews take about 30 to 60 days once they have all the papers they need.
ADU permit site plan checklist
Planning for an ADU starts with gathering facts about your land. You need a full list of data to get a ADU permit. Most cities view these units as habitable space. Because of this, they need building and zoning reviews to ensure the plan is safe to live in. You can check local rules on a city site like San Jose's permit center to see how they handle these tasks.
Gather property and parcel data
You must find your exact property lines and lot size. Look for your parcel number on a tax bill or deed. This helps you find the legal bounds of your land. You will also need to mark all existing structures like your main house, sheds, or decks. Knowing where things sit now is the first step before you add a new footprint to the site.
Plan the ADU footprint and setbacks
Define the size and spot for your new unit. Many cities limit these units to 1,200 square feet or less. You must show the gap from the new walls to the property lines. These gaps are called setbacks. Local laws often set a minimum gap to keep buildings from being too close to neighbors or the street.
Check for utilities and easements
Find out where your water, sewer, and power lines run. Your plan needs to show how the new unit will link to these services. You also need to look for easements. These are areas where others have a right to use your land, like for power lines or pipes. You cannot build on an easement, so you must find them before you start your work.
- Check your address and parcel ID. Make sure your street address and tax ID are correct on all forms.
- Mark all existing buildings. Show the spot and size of your main home and any other structures.
- Map the proposed ADU footprint. Draw the exact spot where the new unit will go on your land.
- Identify all setbacks and property lines. Note the gap from the ADU to your lot edges to meet local zoning laws.
- Locate utility lines and easements. Mark where pipes and wires run to plan your service hookups.
- Confirm local city requirements. Each city has its own rules, so talk to your local office to get their specific list.
Once you have this data, you can move to the next phase. Having a clear plan helps you apply for building permits with less stress. A good site plan shows the city exactly what you want to build and where it will go on your lot.
Why do ADU permit requirements vary by city?
Local zoning and land use
Every city sets its own rules for how land is used. These local laws decide where you can build on your lot. Some towns may allow large guest houses, while others keep them small. This is why an ADU permit in one place looks different from another. Local boards want to keep the look of the area the same. They use zoning to control things like height and how much of your yard the building takes up.
Many cities cap these units at 800 to 1,100 square feet. Other areas may say the unit can only be half the size of your main home. These rules change based on local housing goals. Some cities want more homes, so they make the rules easy. Others may have strict laws to limit noise or cars. You should always check your city site to see the exact rules for your lot.
Safety and building codes
Each city must also ensure that new homes are safe. They use building codes to check for fire safety and strong walls. Because ADUs are habitable space, they must meet high standards. Some cities have special rules for areas with high winds or risk of fire. This means the permit steps will change to match local risks.
A city might need a full review of your plans to check for safety. This review often looks at how the unit handles weight and weather. Cities in dry areas might need better fire walls. Cities in snowy spots might need stronger roofs. These local needs mean you cannot use one plan for every site. You need files that show you meet each local safety rule.
Utility and site needs
How your ADU connects to water and power is another big factor. Some cities have old pipes that cannot take more load. In these cases, you might need extra permits for pipes or wires. The city wants to make sure your new unit does not hurt the local grid. This is part of the review for your building permit.
The slope of your land can also change what the city asks for. If your lot is steep, you might need more data on how water flows. Each site is unique, so each permit file is too. Most cities require a site plan to show where the new unit sits near property lines. Checking with your city or county first helps you avoid small errors that slow down your project.
How does the ADU type change the permit package?
Getting an adu permit is a big step for your project. The type of unit you build will change what you need to give the city. A small room in your house is not the same as a new guest cottage. Each choice has its own set of rules for safety and size. The city needs to see how the unit fits on your land and fits with your main house.
Since these units provide complete independent living facilities, they must follow building codes. Your permit package proves that your new home is safe for people to live in. The unit type you choose guides the maps and forms you must submit. Planning ahead helps you get your permit faster and with fewer errors.
Detached units and lot space
A detached unit is a house that stands on its own. These are often the most hard projects for an adu permit. You must show right where the new house sits on your lot. The city will check if it is too close to your land lines or your main home. These gaps are known as setbacks. If you have a small lot, showing these clear gaps on a site plan is vital.
The city also looks at how high the new building will be. Many places limit the height of these units to 25 or 30 feet. This rule helps keep the area looking the same and keeps your life private from your neighbors. You must also show how people will reach the new unit from the street. This can mean adding new paths or driveways to your plan.
Garage and basement changes
Changing a garage or basement is a smart way to use space. For this type of accessory dwelling units project, your site plan focus shifts. You might not be building a new house from the ground up. Still, the city wants to see the layout. They need to know how the change affects your land.
If you convert a garage, you might lose your parking spots. Many cities require you to show where you will park your cars now. These ADU permit requirements can be tricky, so having a good plan is a must. You must also show how pipes and power will get to the unit. The plan checker will check to see if the old building can handle the new use. These plans help the city make sure that your project is safe.
Junior units and small spaces
Junior units, or JADUs, are very small homes inside your current house. Most are 500 square feet or less. Because they stay within your old walls, the permit process is often faster. You may not need as many new maps for the outside of your land. But you still must show the unit has its own door and a small kitchen area.
Even with a small unit, you must follow local laws. The city wants to see how the unit connects to the main home's pipes. You may also need to show that the unit does not change the look of the street. Each city has its own rules for JADUs, so checking your local code is key. A clear site plan helps the checker get your small project quickly.
| ADU Type | Site-Plan Focus | Added Docs |
|---|---|---|
| Detached | Setbacks and height | Drainage plans |
| Attached | Lot coverage | Wall details |
| Conversion | Parking and power | Old floor plan |
| Junior | Inside layout | Kitchen details |
Common ADU site plan review delays
Getting an adu permit can take 30 to 60 days. But this wait time grows if your city finds errors in your plans. Small mistakes can cause the city to send back your paperwork for fixes. This stops your work and can cost you more money. Knowing why plans get stuck can help you get your project moving faster.
Missing lot details and measurements
One of the most common reasons for a delay is missing data on the lot. Your site plan must show the exact size of your land. It also needs to show the space between each building. If you do not list the size of the new unit, the city cannot check if it fits your local rules. Most cities have strict laws about how much of your lot you can cover with roofs and floors.
You also need to show all current structures. This includes sheds, decks, and even large trees in some towns. If the city sees a building in a photo that is not on your plan, they will ask for a fix. This often leads to a second look, which adds weeks to your plan. Making sure every line and label is clear helps you apply for building permits with more ease.
Setbacks and utility lines
Cities use site plans to check for safety and land use rules. A big part of this is the setback. A setback is the space between a building and the property line. Many accessory dwelling units must sit a set distance from fences or other homes. If your plan does not clearly mark these gaps, the city will flag it.
Utility lines are another common spot for errors. You must show where your water, power, and sewer lines go. A new unit needs its own lines or clear links to the main house. If your new unit sits on top of a known pipe or wire, the city will say no for safety. Showing these lines early stops a long wait with the city utility team.
Access and label errors
City staff also look at how people will get to the new unit. If you are building a unit in the back, you must show a clear path from the street. This path must be wide enough for fire crews or medics to use. If the path is too thin or blocked by other walls, your permit will not move forward. Parking rules also matter. Your plan needs to show where people will park. If you leave this out, the city might think you are not following local laws.
Keeping labels the same is also key for a fast review. If your plan uses different names for the same area, it confuses the city. Keep your words the same across all your pages. Most cities consider these units live-in space and need zoning and building permits to ensure they meet all code rules. Using an expert drafting team helps you avoid these simple traps and keeps your build on track.
From site plan to a complete ADU permit submission
Turning your dream of a new home space into a real building starts with a clear plan. You must move from a rough idea to a full set of files for the city. This step is about more than just drawing. It is about using a set list of rules. This helps you get your adu permit without extra stress or delay. A good process keeps your project on track and helps you avoid costly errors.
Local rules for ADU projects
Before you spend time on drawings, check if your land allows an ADU. Every city has its own rules for size and height. Some towns have strict limits on how big your unit can be compared to your main house. Most places view an ADU as a real living space. This means you will need a complete building and zoning permit before you can start any work. Checking these rules early helps you avoid big fines or legal issues later.
You should also look for utility rules. Your new unit might need its own water or power lines. Some cities let you use the lines from your main house, but others do not. Knowing these facts now will help you plan your budget. It also helps you talk to the city staff with ease. They like to see that you have done your work before you ask for a permit.
The city document checklist
Once you know you can build, get the checklist from your local permit office. This list tells you just what you must turn in. Every city is not the same, so do not guess what they need. A common package for an ADU includes many types of plans. You will need a site plan that shows where everything sits on your lot. You also need floor plans that show the inside layout and roof plans for the top of the unit.
It is helpful to have a full list before you start. This makes it much easier to apply for building permits because you will not miss any small details. Make sure you have all the trade plans ready too. These include:
- Electrical plans for lights and outlets.
- Plumbing plans for water and waste.
- Mechanical plans for heating and cooling.
- Energy use reports that show how well the unit keeps in heat.
The plan review process
After you get your site plan and other files, you are ready to submit them. Many cities now use online portals for this work. You can upload your PDF files and pay your fees from your home computer. Once you send your files, the city staff will review them. This often takes about a month or two. They will check your plans against local laws to make sure everything is safe and legal.
Do not worry if the city has questions or asks for changes. This is a common part of the process. They might send you a list of notes that need an answer. You can update your plans to match their needs and send them back. An expert drafting service can help you make these small fixes fast. They use GIS and satellite data to create files that meet city standards. This keeps your project moving so you can get your ADU permit requirements met and start building your new space.
How My Site Plan helps with an ADU permit
My Site Plan helps you get your ADU permit files ready. Most towns see an ADU as a place to live, so you often need zoning and building permits to build one. A site plan shows the city where the new unit will go and lists lot lines in a clear way.
Fast and remote drafting services
Our team uses GIS and space maps to create a site plan for permit use. You do not need to wait for a person to visit your home because this remote work saves you time and stress. We send your plan to you in under 24 hours so you can start your project much faster.
We do not use physical surveys to make our plans but rely on high-tech maps and aerial views. This means we can help you no matter where you live in the U.S. Our process is fast and keeps the cost low for you while giving you the same quality work without a site visit.
Meeting city requirements
Local building offices have strict rules for new housing and want to see how your ADU fits on your lot. A site plan from us shows your lot lines and current buildings. It also shows the planned ADU and its spot on your land. This helps city staff review your permit form faster.
Many cities limit how big an ADU can be and may cap the size at about 800 to 1,100 square feet. Our plans show the size of your new unit and the height of the unit to meet local privacy laws. These facts are key for your permit approval.
Reliable site plans you can trust
We offer clear and open pricing for our work. If the city needs a change to the site plan, we provide free edits and do not charge extra for these updates. We also stand by our work with a 100% money-back promise to make sure your plan is ready for the permit office.
Building without a permit can lead to big fines or even forced removal of the structure. Our site plans help you stay in line with city rules from day one. We give you the papers you need to move forward with your build.
Frequently Asked Questions
Do I need a building permit to build an ADU?
Most cities need building and zoning permits to build an Accessory Dwelling Unit. These units are livable spaces, which means they must follow strict safety and land use rules. You may also need utility permits to connect power or water lines. According to the City of San Jose, these permits ensure your new home is safe for people to live in.
What happens if I build an ADU without a permit?
Building without a permit can lead to heavy fines or legal trouble. Cities may even force you to tear down the building if it does not meet code. This can cause major problems when you try to sell your property later. The City of San Jose notes that unpermitted work can hurt your home value. It also makes it hard to get loans when you want to sell.
Do I need a professional site plan for an ADU permit application?
Yes, most cities need a detailed site plan as part of your permit form. This map shows where the ADU sits on your lot and how far it is from property lines. It helps city staff check that your project follows local zoning and setback laws. Having a good plan can speed up the review and prevent costly errors. Many people use a permit checklist to ensure they have all needed papers ready.
Is there a difference between a permit for an ADU and a JADU?
Junior Accessory Dwelling Units, or JADUs, are smaller units often limited to 500 square feet. Because they are smaller and built inside an existing house, they often have easier permit rules than full ADUs. For example, some cities may not need a full separate water connection for a JADU. As noted by the City of San Diego, these small units provide an easy way to add living space.
Ready to order your ADU site plan online?
Waiting to start your project can cost you time and money, so getting your plan fast helps you keep your project on track. If you wait to file for your permit, your ADU stays as a plan while building costs go up. You can move forward now and avoid a slow drafting process by getting your plan in 24 hours.
Do you want to avoid the long wait for a map based plan? Our team creates clean site plans that meet city rules for lot space. You can also read our guide on how to apply for building permits to learn more. Order your ADU site plan online to request your plan today. We offer a money-back promise if the city does not accept your plan.
