Accessory Dwelling Units

What's an ADU?

An accessory dwelling is a smaller, secondary home located on the same lot as the main dwelling. The category includes:

• Secondary suite, a self-contained unit attached to the main house
• Basement suite, a secondary suite located in the basement
• Carriage house, a detached unit often above a garage
• Garden suite, a small detached stand-alone home in the yard

How many you can build

Per BC's Bill 44 (Housing Statutes Amendment Act, 2023), all BC municipalities were required to update their zoning to permit small-scale multi-unit housing on most residential lots. Castlegar's response is reflected in Bylaw 1428 (Zoning), adopted July 2024.

For the specific rules that apply to your lot (number of dwellings allowed, setbacks, height, parking), submit a Property Information Request or contact Development Services directly. Provincial rules generally permit additional small-scale multi-unit housing on lots in residential zones, with specific thresholds set by lot size.

Zoning rules

The Zoning Bylaw (Bylaw 1428) sets specific requirements for ADUs, including floor area limits, setbacks, height, and parking. These vary by zoning district and ADU type (attached vs. detached). The Property Information Request (Step 1 of any building permit) tells you exactly what applies to your lot.

Utility rates for properties with a suite

The City's utility rates have a separate category called “Single Family with Suite” with its own quarterly base rate and consumption threshold. See the Utility Rates page for the verified 2026 rate table.

Getting started

An ADU project usually goes faster (and cheaper) when you walk into Development Services already knowing your own house. Before you design anything or hire anyone, spend an afternoon gathering these basics about your property:

• Current interior wall materials and structure
• Yard measurements (front, side, rear setbacks)
• Servicing locations: where your electrical panel is, what amperage it has, where water and sewer connections enter the property

Then book a pre-application meeting with Development Services. They'll confirm what's allowed on your specific lot and walk you through the application.

Free design resources

Both the City and the Province publish design guides and standardized ADU designs at no cost. These summarize BC Building Code requirements and can save you significant design fees.

• The City's free guides cover existing-building conversions and new construction
• The Province offers standardized designs through the Standardized Housing Designs Catalogue