{"title":"Duncan secondary suite and carriage house rules","question":"Can I add a secondary suite or a carriage house?","slug":"secondary-suite","place":{"path":"ca/bc/duncan","name":"Duncan","region":{"code":"bc","name":"British Columbia"},"country":{"code":"ca","name":"Canada"}},"category":{"slug":"building-and-renovating","name":"Building, renovating and your property"},"owner":"municipal","owner_label":"Municipal","owner_body":{"name":"City of Duncan","url":"https://duncan.ca"},"short_answer":"Yes. The City of Duncan's zoning allows one attached suite or one detached suite (in an accessory building) per primary dwelling in the Low Density Residential zone, up to 90 m². A building permit is required, and the City offers pre-approved plans with waived plan review and permit fees.","aliases":["carriage house duncan","garden suite duncan","basement suite duncan","accessory dwelling unit duncan","laneway house duncan bc"],"cost":"Plan review and building permit fees are waived if you use the City's pre-approved plans unchanged; otherwise standard building fees apply. Secondary suite inspection $100. Development cost charges are not payable on a first new secondary suite.","how_long":"Not stated on the City's pages.","where":[{"type":"phone","label":"Development Services","value":"250-746-6126"},{"type":"email","label":"Development Services","value":"DevelopmentServices@duncan.ca"},{"type":"email","label":"Building Department","value":"Building@duncan.ca"},{"type":"in_person","label":"City Hall","value":"200 Craig Street, Duncan, BC V9L 1W3"}],"documents":["Building Permit Application with plans meeting the 2024 BC Building Code","Homeowner Protection Office (BC Housing) approval or exemption for a detached suite"],"forms":[{"title":"Small-Scale Multi-Unit Housing, Secondary Suites and ADUs page","url":"https://duncan.ca/city-hall/planning-and-development/ssmuh/"},{"title":"Secondary Suites page","url":"https://duncan.ca/city-hall/planning-and-development/building-permits-inspection/secondary-suites/"},{"title":"Secondary Suite Regulations (older PDF)","url":"https://duncan.ca/download/secondary-suites-building-requirements/"}],"related":[{"slug":"building-permit","title":"Duncan building permits: when you need one and how to apply","url":"https://govhandbook.com/ca/bc/duncan/building-permit/"},{"slug":"building-permit-fees","title":"Duncan building permit fees","url":"https://govhandbook.com/ca/bc/duncan/building-permit-fees/"},{"slug":"zoning-lookup","title":"Duncan zoning: find your zone and what it allows","url":"https://govhandbook.com/ca/bc/duncan/zoning-lookup/"}],"nearby":[{"place":"ca/bc/north-cowichan","name":"North Cowichan","url":"https://govhandbook.com/ca/bc/north-cowichan/secondary-suite/"},{"place":"ca/bc/ladysmith","name":"Ladysmith","url":"https://govhandbook.com/ca/bc/ladysmith/secondary-suite/"},{"place":"ca/bc/north-saanich","name":"North Saanich","url":"https://govhandbook.com/ca/bc/north-saanich/secondary-suite/"},{"place":"ca/bc/lake-cowichan","name":"Lake Cowichan","url":"https://govhandbook.com/ca/bc/lake-cowichan/secondary-suite/"},{"place":"ca/bc/sidney","name":"Sidney","url":"https://govhandbook.com/ca/bc/sidney/secondary-suite/"},{"place":"ca/bc/central-saanich","name":"Central Saanich","url":"https://govhandbook.com/ca/bc/central-saanich/secondary-suite/"}],"topic":{"title":"Secondary suite and carriage house rules in British Columbia, by municipality","url":"https://govhandbook.com/ca/bc/secondary-suite/"},"facts":{"suite_allowed":{"label":"Secondary suite allowed","value":"Attached secondary suites are allowed in Low Density Residential (LDR), and in Medium and High Density Residential only in multi-unit rowhouse dwellings. Zoning permits up to four dwelling units on LDR parcels.","short":"Yes, in Low Density Residential zones","status":"stated","sources":[{"url":"https://duncan.civicweb.net/document/175322","title":"Zoning Bylaw No. 3166, 2017 (PDF, consolidated to August 24, 2026), section 4.3","section":"s. 4.2.1, 4.8.2, 4.1.1","quotes":["Secondary Suite, Attached","An attached secondary suite is only permitted in a multi-unit rowhouse dwelling","permit up to four dwelling"]},{"url":"https://duncan.ca/city-hall/planning-and-development/ssmuh/","title":"Small-Scale Multi-Unit Housing (SSMUH), Secondary Suites, and ADUs, City of Duncan","section":"SSMUH page","quotes":["permit up to 4 dwelling units on parcels zoned Low Density Residential (LDR)"]}],"check":{"result":"matched","text_date":"2026-11-06"}},"detached_allowed":{"label":"Coach house or garden suite allowed","value":"Allowed as an accessory use in the LDR zone (one detached secondary suite per primary dwelling, in an accessory building on a parcel with a single-unit dwelling).","short":"Yes, in LDR zone; one per dwelling","status":"stated","sources":[{"url":"https://duncan.civicweb.net/document/175322","title":"Zoning Bylaw No. 3166, 2017 (PDF, consolidated to August 24, 2026), section 4.3","section":"s. 4.2.1, definitions","quotes":["Secondary Suite, Detached","means a secondary dwelling unit located in an accessory building","on the same parcel as a single-unit dwelling"]}],"check":{"result":"matched","text_date":"2026-11-06"},"sources_differ":"The City's Secondary Suites Regulations PDF says detached suites require a minimum 600 m² lot, but the current zoning bylaw (amended May 2025) states no lot-size minimum for them; the City's web page says detached suites 'may be permitted where parcels meet the minimum lot size'. Check with the City."},"limits":{"label":"Limits","value":"LDR: one attached or one detached secondary suite per primary dwelling unit; maximum floor area 90 m². Detached suites must be at least 2.5 m from the main dwelling; an accessory building with a second-storey detached suite may be 7.5 m high. The zoning text sets no owner-occupancy requirement.","status":"stated","sources":[{"url":"https://duncan.civicweb.net/document/175322","title":"Zoning Bylaw No. 3166, 2017 (PDF, consolidated to August 24, 2026), section 4.3","section":"s. 4.3.2, 4.3.3, 3.11.2, 4.3.1","quotes":["The maximum number of suites is one attached secondary suite or one detached","secondary suite per primary dwelling unit","The maximum gross floor area of an attached secondary suite or detached","suite is 90 m2","Detached secondary suites must be sited at least 2.5 m from a principal","7.5 m for buildings with a detached secondary suite on","The maximum gross floor area of an attached secondary suite or detached secondary"]}],"check":{"result":"matched","text_date":"2026-11-06"},"sources_differ":"The older Secondary Suite Regulations PDF gives percentage limits (attached 40%, detached 60% of the house, or 90 m²) that the current zoning text does not repeat. Searched zoning text for 'owner' occupancy: not checked in detail."},"parking":{"label":"Parking","value":"1 off-street space per dwelling unit, so one for the suite as well as one for the main dwelling. A second space may sit behind the first with a shared access.","short":"1 space per dwelling unit","status":"stated","sources":[{"url":"https://duncan.civicweb.net/document/175322","title":"Zoning Bylaw No. 3166, 2017 (PDF, consolidated to August 24, 2026), section 4.3","section":"s. 3.28.1, 3.25.4","quotes":["Residential Use","1 per dwelling unit","may be arranged such that one space is located","behind the other space"]},{"url":"https://duncan.ca/city-hall/planning-and-development/ssmuh/","title":"Small-Scale Multi-Unit Housing (SSMUH), Secondary Suites, and ADUs, City of Duncan","section":"SSMUH page","quotes":["One on-site parking stall is required for each dwelling unit."]}],"check":{"result":"matched","text_date":"2026-11-06"},"sources_differ":"The older Secondary Suite Regulations PDF says one extra space for the suite plus two for the main dwelling; the current zoning bylaw says 1 per dwelling unit, so it is followed."},"permits":{"label":"Permits","value":"A building permit is required (plans meeting the 2024 BC Building Code). Detached suites also need Homeowner Protection Office approval or exemption. Buildings with three or more units need a Development Permit. A $100 secondary suite inspection fee applies. Building permit and plan review fees are waived if you use the City's pre-approved ADU plans unchanged.","status":"stated","sources":[{"url":"https://duncan.ca/city-hall/planning-and-development/ssmuh/","title":"Small-Scale Multi-Unit Housing (SSMUH), Secondary Suites, and ADUs, City of Duncan","section":"SSMUH page","quotes":["A building permit application to the City is still required","All multi-unit residential buildings (defined as a building with three or more dwelling units) will need to be authorized by a Development Permit","Building Permits are issued for construction that conforms to the 2024 BC Building Code"]},{"url":"https://duncan.ca/city-hall/planning-and-development/building-permits-inspection/secondary-suites/","title":"Secondary Suites, City of Duncan","section":"Secondary Suites page","quotes":["Freestanding residential buildings require Homeowner Protection Office approval or exemption"]},{"url":"https://duncan.civicweb.net/document/181386","title":"Fees and Charges Bylaw No. 3212, 2020 (PDF, consolidated to August 24, 2026)","section":"Schedule E","quotes":["7. Secondary Suite Inspection Fee","$100.00"]}],"check":{"result":"matched","text_date":"2026-11-06"}},"bylaw":{"label":"Bylaw","value":"Zoning Bylaw No. 3166, 2017 (amended to August 24, 2026), s. 4.3 and definitions","status":"stated","sources":[{"url":"https://duncan.civicweb.net/document/175322","title":"Zoning Bylaw No. 3166, 2017 (PDF, consolidated to August 24, 2026), section 4.3","section":"Part 4 LDR","quotes":["Low Density Residential Zone","Secondary Suite, Detached"]}],"check":{"result":"matched","text_date":"2026-11-06"}}},"facts_summary":{"total":6,"stated":6,"matched":6,"none":0,"unknown":0},"body_markdown":"## How it works\n\nThe City of Duncan's [Zoning Bylaw](https://duncan.civicweb.net/document/175322) allows one attached or one detached secondary suite per primary dwelling in the Low Density Residential (LDR) zone. A detached suite is an accessory use in an accessory building on a parcel with a single-unit dwelling. In Medium and High Density Residential zones, attached suites are allowed only in multi-unit rowhouse dwellings. LDR zoning also permits up to four dwelling units on a parcel. Not all housing forms are allowed on all parcels, so check your lot first.\n\n## Steps\n\n1. Confirm your zone with Development Services at 250-746-6126.\n2. Check flood plain status: LDR parcels east of the Trans Canada Highway are in a flood plain with extra requirements.\n3. Decide whether to use the City's pre-approved ADU plans or a custom design.\n4. For a detached suite, get Homeowner Protection Office (BC Housing) approval or an exemption.\n5. Apply for a building permit with plans meeting the 2024 BC Building Code. A driveway access permit is needed for any new access.\n\n## Good to know\n\n- Maximum suite floor area is 90 m². A detached suite must be at least 2.5 m from the main dwelling, and one on the second storey of an accessory building may be 7.5 m high.\n- Parking is 1 off-street space per dwelling unit, so one for the suite as well as one for the main dwelling.\n- The City's older Secondary Suite Regulations PDF says otherwise on some points (a 600 m² minimum lot for detached suites, percentage size limits, more parking). The current zoning bylaw does not repeat these, so confirm with the City.\n- Buildings with three or more units need a Development Permit.\n- The City's pages mention an additional utility charge for secondary suites; ask Development Services what applies.\n- Pre-approved plans waive only the plan review and permit fees; other costs such as the $100 suite inspection still apply.","sources":[{"url":"https://duncan.ca/city-hall/planning-and-development/ssmuh/","title":"Small-Scale Multi-Unit Housing (SSMUH), Secondary Suites, and ADUs, City of Duncan","accessed":"2026-11-05"},{"url":"https://duncan.ca/city-hall/planning-and-development/building-permits-inspection/secondary-suites/","title":"Secondary Suites, City of Duncan","accessed":"2026-11-05"},{"url":"https://duncan.civicweb.net/document/175322","title":"Zoning Bylaw No. 3166, 2017 (PDF, consolidated to August 24, 2026), section 4.3","accessed":"2026-11-05"},{"url":"https://duncan.civicweb.net/document/181386","title":"Fees and Charges Bylaw No. 3212, 2020 (PDF, consolidated to August 24, 2026)","accessed":"2026-11-05"},{"url":"https://duncan.ca/download/secondary-suites-building-requirements/","title":"Secondary Suite Regulations (PDF), City of Duncan","accessed":"2026-11-05"}],"sources_read":"2026-11-05","review":{"status":"machine_checked","badge":"Checked against official text","label":"Checked by script, not yet by a person: the official wording behind 6 of 6 facts was matched to the official text."},"urls":{"html":"https://govhandbook.com/ca/bc/duncan/secondary-suite/","markdown":"https://govhandbook.com/ca/bc/duncan/secondary-suite.md","json":"https://govhandbook.com/ca/bc/duncan/secondary-suite.json"}}