Costs of getting a building permit for your ADU

Custom Backyard home

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

You should know the answer by now – it depends.

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.

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

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 for your new backyard home?

  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 site analysis and, in general, looking out for the red flags that could become roadblocks on the fast lane towards an ADU.

It includes the analysis of your city regulations, height and size restrictions, and zoning requirements.

The cost of it differs from $500 to $5000. 

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).

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 start 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. And do not let your architect make rookie mistakes.

Structural engineer will charge you around ~$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. 

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

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.

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 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.

So if the budget is tight, do your homework before you start your project. Do not forget to have your contractor walk the property with you to determine potential cost items.

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