GR Zoning Rules for ADUs

In April 2024, the GR City Commission adopted a few zoning text amendments! This was a huge change that relaxed a few of the previously stringent requirements that made it difficult and costly to build ADUs. You can read the exact language on page 5 of this attachment. As of April 8, 2025, everything I describe below is accurate, however, zoning does change, so if you want to view the living copy, it’s available online in Section 5.9.03.

What is an ADU?

An Accessory Dwelling Unit (ADU) is a smaller, secondary home built on the same lot as a main house. Think of it as a guest house, an in-law suite, or a backyard tiny home. They can either be attached to the primary house (AADU) or detached (DADU). If it’s attached, your primary home technically becomes a duplex—just with a small second unit. You could also create an attic or basement unit and either could be considered an attached ADU. ADUs are a great way to provide affordable housing, accommodate family members, or create additional rental income—if done within city guidelines.

The Basics of Building an ADU

Number of Units

You’re allowed only one ADU per property. So, no stacking up mini-homes on a single lot!

Where You Can Build

ADUs are only permitted with single-family homes or duplexes (two-family homes). That means apartments or commercial properties don’t qualify.

Minimum Lot Size

Your lot must meet the zoning district’s size requirements. In short: if your lot is too small for your zone, you might not be able to build.

Design and Size Guidelines

Setbacks

• Attached ADUs must follow the same setbacks as the main home.
• Detached ADUs follow the setbacks for accessory buildings (e.g. garages or sheds).

Size Rules

ADUs must stay within these size limits:

• Smallest allowed ADU is 400 sq. ft.
• Maximum: 40% of your main home’s size or 400 sq. ft., whichever is larger.
• Never exceed 850 sq. ft. total.
• Never exceed the maximum permitted square footage for accessory structures in your zone. (Usually 832 sq. ft. for most lots in GR).
• If you’re creating an ADU above an accessory structure, you can double the amount of square footage allowed but that space can only be used for an ADU.

Height Limit

• Detached ADUs can be up to 25 feet tall.
• Attached ADUs can be as tall as the primary structure (usually 35 feet).

Practical Considerations

Bedrooms

You can include up to 2 bedrooms in an ADU. Enough for a cozy, functional space!

Renting Your ADU

ADUs cannot currently be short-term rentals (less than 30 days). If you’re renting out your ADU, you need to register it according to city rules.

Maintaining the Look

Any new builds or modifications must match the design and style of the main house. This includes roof shape, windows, siding, etc.

Getting an Address

Each separate building on a lot generally requires its own address, which is vital for emergency services and other official purposes. To request a new address, use the City’s Citizen Access portal. Navigate to the “ADDRESS APPLICATIONS” section and select the “New or Changed Address” option. The process is straightforward and usually takes just a few days.

Once the address has been assigned, visit your local Postmaster General to have the address added as a delivery access point and included in a local delivery route. The Postmaster will also provide guidance on where to place the mailbox for the unit to ensure proper mail delivery.

Important Legal Notes

Deed Restrictions

You can’t sell the ADU separately from the main house. A legal deed restriction will be recorded to enforce this. We can provide a simple example that has worked well for us, or you can pay an attorney to craft one for you.

Permits and Approvals

Before starting construction, ensure your plans meet zoning rules and get the necessary permits.

Why ADUs Matter for Our City

ADUs can help the housing crisis, enable families to live closer together, and improve property values when done responsibly.

If you notice anything is no longer true, please reach out, so we can update it.