Everything You Need to Know About City Permitting for ADUs

by Ben SanfordOctober 23, 2017

Learn the Ins and Outs of Building Accessory Dwelling Units Before You Build

With the tiny home trend gaining steam across the country, more and more homeowners are strongly considering making the shift to more simplistic (and minimal) lifestyles. But, simply buying a piece of land and placing a tiny home on it isn’t as easy as you might think. Despite the popularity of the trend, tiny homes are still not considered legal dwellings in the vast majority of states.

One way you may be able to get around this legal conundrum is to build the tiny home (or guest house) on the plot of land where your permanent residence currently sits. It can then be classified as an “accessory dwelling unit,” or ADU. But, even with this scenario you might not be out of the woods because different cities have different permit requirements for these types of structures.

Here, we help you gain a better understanding of what you might be up against should you want to build an ADU on your property.
Building An ADU

What Counts as an ADU?

An accessory dwelling unit is any structure on a property other than the existing home that can also serve as living space. While tiny homes are the current trend, ADUs have been around for some time and have gone by names such as mother-in-law apartments, guest houses, granny flats, and studio apartments.

Reach Out to Your Local Zoning Commission Before You Start

As stated above, there is no uniform national rule for accessory dwelling units. Every city and state has different requirements that must be met in order for the structure to comply with the local zoning laws. This means a visit to your local zoning commission will be where you’ll want to start.

Your city’s planning and zoning department will be able to tell you exactly what is allowed to be built on your land and what isn’t. You will also learn about the variety of different permits you will need to make sure your structure is legal.

You can get started on your research by visiting accessorydwellings.org, where you’ll find a list of state and city regulations. Of course, you won’t want to rely solely on the information of the website. Always double check your findings through your local zoning commission.
Building an ADU

General ADU Requirements

Most local zoning codes feature a wide variety of design and use standards which apply to the building of an accessory dwelling unit. Such standards include zoning requirements, construction and utility standards, limitations on how many residents can live in the unit, the exterior appearance of the unit, materials used, limitations on certain home occupations, and the physical size of the unit. Permits will be required for all electric, plumbing, and/or mechanical components.

When converting an existing unfinished space to an ADU, some features, such as ceiling heights, windows, stairs and insulation, may not meet current building code requirements for finished space. These conditions could make it expensive, difficult, or even impossible for you to change your attic, basement, or garage into living space.

Requirements for Obtaining a Permit to Build an ADU

The following is a general list of things you will need to present to the zoning board when applying for a permit to build an accessory dwelling unit. Keep in mind that your local zoning board may or may not require additional information.

  • Completed building permit application form
  • Four (4) copies of site, architectural, and structural plans
  • Completed NSFR Intake Packet if the ADU will be a detached structure
  • Completed residential system development charge form
  • A set of site and building construction plans which need to include:
    • Completed standards and drawing criteria for new construction or alterations to an existing structure as required in the NSFR Intake Packet
    • Erosion control plan if the project will require ground disturbing activity. Some cities require erosion control measures to be installed, inspected, and approved before the building can begin
    • Mitigation form and/or a storm water plan if your project will add more than 500 square feet of impervious area

Building an ADU
There are dozens of reasons why adding an accessory dwelling unit to your property can be beneficial. From providing an elderly family member with lodging to serving as a detached home office to serving as a convenient revenue-generating rental, ADUs can help you get the most value out of your land.

Just remember, in order to avoid legal complications, you need to build your dwelling in compliance with your local requirements. As painstaking as the process can sometimes be, there is simply no way to avoid it if you want to ensure you build your ADU legally.

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About The Author
Ben Sanford
Ben is a real estate agent and freelance writer. He's lived on the east coast his entire life and is just as "at home" on a snowboard as he is in the office. When not writing about local real estate markets and researching hot new tips for homeowners, he can be found working on his home renovation projects with help from his wife Melissa and their kids, Josh and Cheyenne.