National Minimum Regulation (NMR)

National Minimum Regulation (NMR)

The National Minimum Regulation (NMR) applies a lenient set of zoning bylaw requirements for building detached ADUs on residential lots. Our team designed the NMR to conduct a baseline analysis in all cities to understand the maximum potential for building detached ADUs under a permissive policy scheme. 

ADUSearch users can explore the results of the NMR analysis in the neighbourhood view of our mapping tool. By comparing the number of lots that are suitable for a detached ADU under existing bylaws with the number of suitable lots in a NMR scenario, the map can highlight areas with a high potential to relax requirements and increase housing supply. 

Our team has designed the NMR to be responsive to local neighbourhood characteristics. The NMR’s detached ADU requirements, therefore, are more permissive in urban areas than in suburban areas. To identify local neighbourhood characteristics, we used 2021 census data to categorize census tracts into three distinct typologies: urban, intermediate, and suburban. 

Census tracts were considered Urban if they had all three of the following criteria:

  • High population density
  • Low rates of single-family housing
  • Small average lot sizes

Census tracts were considered Suburban if they had all three of the following criteria: 

  • Low population density
  • High rates of single-family housing
  • Large average lot sizes

Census tracts were considered Intermediate if they had a mix of both urban and suburban criteria. 

The NMR adapts setbacks, ADU placement, required main dwelling type, and main dwelling setbacks based on the assigned typology of the lot. For lots in Suburban typologies, the NMR applies a lot coverage maximum of 60%, applies main dwelling and lot line setbacks of 1 meter, and limits buildable areas to rear and side yards. The NMR also requires the main dwelling be a single-family home in order to identify the lot as suitable for a detached ADU. 

In Suburban and Intermediate typologies, the NMR applies a lot coverage maximum of 60% and limits the buildable area of a lot to the rear and side yards. The NMR applies a rear and side setback requirement of 1 meter to suburban lots and 0.5 meters to intermediate lots. Urban lots have no lot coverage maximums and no setback requirements. The main dwelling setback requirement for all lots is 1 meter.

Chart layout of information described in preceding and proceeding test.

Based on these requirements, the NMR calculates buildable areas for lots that fall under the NMR lot coverage maximum and that fall outside of any environmental protection zone that typically precludes development – for example, a floodplain. The minimum size detached ADU in the NMR is 20 metres squared. Any lot with a calculated buildable area that is equal to or more than 20 metres squared is categorized as suitable for a detached ADU in the NMR. 

For more details and background about our NMR analysis, visit our Data Exports page to read our methodological report.