Costs of Getting a Building Permit for Your ADU

building permit

Costs of getting a building permit for your ADU

7min read
by Olesia Chikunova, ADU Specialist.

Building permit paperwork

How much does it cost to get a permit for an accessory dwelling unit?

It does not matter if you are building your accessory dwelling unit with a modular company, or a custom backyard cottage with a traditional stick-built builder, you will need to get the building permit from your city. There is no escaping this cost. It might be hidden in all-in-one price. But it is there. And the total cost of getting the permit might be anywhere between $20,000 and $30,000. That is assuming you have not hired a famous architect. If you have, you will be paying even more.


Some builders call it “soft” costs, while they refer to construction costs as “hard” costs.

Building permit application

The industry term is pre-construction. This is the only phase of your project where you have the chance to save money. This is the phase where the scope of work is determined, and the rest follows. As soon as the construction detail gets into the plan set and then gets permitted, any change order will lead to project delays and cost overruns.

What is included in the pre-construction phase?

  1. Feasibility & ordinance study
  2. Site survey
  3. Architectural drawings
  4. Structural Engineering
  5. Grading and drainage plan
  6. Energy Calculations
  7. CalGreen checklist
  8. City fees
  9. Printing costs

What is feasibility study?


Feasibility study starts in your backyard.

It includes the analysis of your city regulations, site analysis, understanding height and size restrictions, and, in general, looking out for the red flags that could become roadblocks on the fast lane towards an ADU.

The cost of it differs from $500 to $5000 depending who you ask.

Why do you need a site survey?

Site survey can cost you anywhere from ~$2500 to ~$7000+ depending on the size of the lot and the amount of information of record the surveyor has on your property. You might be tempted to skip this step, however, if you are building anywhere close to property lines you really should not. It is messy business to find out in the middle of construction that you are encroaching on the neighbor’s property.

Additional complication is easements. The city will not allow building on the easement, and it is really silly to draw the plans first only to find out that you cannot build a 1000sf unit you had set your heart on because some oil company has easement across your property (happened before, you know, though utility easements are more typical).

Young surveyor at work with modern tools

Costs of construction documents

Architectural drawings

Are you looking for a simple off the shelf solution? You can go with a modular company that has design baked into the product. As long as you like the layout, its exterior finishes and the company can crane the unit onto your property, you gain thoughtful design and speed of construction.

Some architects also sell ready to go plan sets for custom builders, with structural engineering, Title 24 calculations included. These usually run around ~$8000+. In this case, you get the stamped plans ready to be submitted – but no changes. All the additional tweaks will be at the architect’s hourly fee.


If you have some specific design requirements, then it might make sense to go custom and work with the architect or designer of your choice to develop a unique solution.

Make sure the architect includes a CalGreen checklist, a requirement for all newly constructed buildings.


Engineering calculations and drawings 

Structural engineer will charge you  ~$3500 for a simple ADU project.

Grading and drainage plan will cost you ~$3000 more.

For energy calculations, a.k.a. Title 24, add ~$400.

You might need an arborist if you have any heritage trees that need protection – add ~$1000 to the bill.

Your estimates may differ – every backyard is different.

Printing costs should not be discarded either, I have recently paid ~$200 for the five paper copies of the plan set that I had to deliver to the city along with the corresponding pdf file.

What fees will the city charge?

City permit submittal costs hide different types of fees:

  1. Recovery fees
  2. Impact fees
  3. Connection fees


Recovery fees are paid for the time spent by the planner on your case.


An impact fee is imposed by a local government on a new or proposed development project to pay for the costs of providing public services.  Impact fees have become an essential part of local governments to fund infrastructure and go towards the development of needed parks, schools, roads, sewer, water treatment, utilities, libraries, and public safety buildings. Most of them waived for units under 750 sf.


It might sound illogical that you will be charged for connection fees, as you are adding a secondary building, so all main utilities are already there, right? Well, a certain Bay Area county had charged a homeowner a whooping $36,000 for a water connection. Go figure.

Signage for building permit on construction site

Benefits of getting the building permit

There are several benefits to obtaining a building permit. The elephant in the room is Peace of Mind.
You can be a famous actor, and still get a fine if you decide to build without permit. Sylvester Stallone who was fined in 2018 for illegally carrying out work on his home. Yes, he was working on extensive renovations in Los Angeles without obtaining the necessary permits. The construction work included adding a gym and a guest house to the property, extensive grading and retaining walls. The fine was for $200,000, plus the unhappy homeowner was required to remove some of the unauthorized construction work.

Additional benefits to getting a building permit include:

1. Ensuring Safety. The city issues building permits after making sure the drawings are up to current codes. Current codes are more stringent than what was acceptable in the last century. Have you heard about the story of one city in Turkey that was left almost untouched by the earthquake? Why? The local authorities made it a priority to have high construction quality standards. We have more data. We have better products that protects us from fires, floods and earthquakes. Also, building permits ensure that the construction work is done safely. For you, your neighbors, environment.
2. Legal Compliance. Building without a permit is illegal and can result in costly fines or legal action. What is worse, the local enforcement agency can out a red tag on your property. You will not be able to complete the project until the local jurisdiction considers the project compliant. A permit confirms you are compliant with local laws and regulations. It can help you avoid any potential legal issues. Who wants to stop in the middle of construction to start a permitting process? Do you know how easy it is for a neighbor to call your city and check if you are building with a permit?
3. Inspection and Quality Control. Building permits require inspections at various stages of construction. The project flows through various stages – each with its own inspection milestone. Foundation, framing, rough electrical, plumbing etc.
Every trade needs to pass an inspection before the next trade can continue working on the project. Inspections ensure the work has been done properly and to code, which can prevent future problems or costly repairs. Reassuring, right?
4. Property Value. Having a building permit can also increase the value of your property. Do you think you may sell the property one day? Potential buyers may be hesitant to buy a property without proper permits and inspections. At the same time you will have to make disclosures. Yes, unfortunately, a permit may also increase the taxes.
5. Insurance Coverage. Accidents happen. In case of any damage, insurance companies may deny coverage if they suspect the construction was done without the proper permits.
Obtaining a building permit can save you time, money, and headaches in the long run. Do you want to prevent problems down the road? Get the building permit to ensure that the construction work is done safely, legally, and to the required standards.
Checking measurements on site with tape and construction drawings

What happens if neighbors complain?

If neighbors complain about an un-permitted construction project, the city will need to act. The enforcement officer will come out and check the property for violations. ALL violations. Not just the one you are working on now.
The officer will issue a stop-work order, impose fines, and demand the owner obtains the necessary permits.
Another popular reason to call the city is Noise or Nuisance Complaints. We had police come out once because a neuighbor though we were too loud. We had the arborist on site confirming the foundation location. If the neighbors are complaining about noise, the owner will need to address the complaints. Typically building permit documentation includes the hours that the crew can work. The information is also available on the city or county websites.
The work done without proper structural calculations may cause damage to neighboring properties. The owner may be liable for the damages and required to pay for repairs.
You do not want your neighbors to take legal action against you. There is nothing worse than a neighor feud.
It’s important for construction project owners to be aware of and comply with local laws and regulations. It is equally important to be respectful of your neighbors and their property rights.
Just do it right the first time around.

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