What records explain additional residential units at a Markham home?
Section 4.9.9 of the City's comprehensive Zoning By-law 2024-19, as amended by By-law 2026-44, in the office consolidation to 20 July 2026, and the City's Secondary Suites guide for homeowners (April 2026).
Sources checked October 29, 2026
The rule in Markham
Up to 3 homes on a lot
Markham zoning by-law 2024-19 s.4.9.9: permits up to two additional residential units inside a detached, semi-detached or townhouse dwelling, or one inside and one in an accessory building, under Zoning By-law 2024-19 (not in a GWY1 zone or TRCA hazard lands; properties outside 2024-19 follow older zoning by-laws); every suite must be registered with Markham Fire and Emergency Services.
From Markham by-law 2024-19 s.4.9.9, checked 29 Oct 2026
- The recordAdditional residential units
- Where to read itZoning By-law 2024-19, office consolidation; Secondary Suites: Guide for Homeowners and 1 more
- The free check reads itPick “Extra units allowed”
What the record shows
Section 4.9.9 of Zoning By-law 2024-19, as amended by By-law 2026-44, permits additional residential units only on a lot with a detached, semi-detached or townhouse dwelling: no more than two located entirely within the house, or, where one is in an accessory building, only one in the house. They are not permitted in a GWY1 zone or within hazard lands as prescribed by the Toronto and Region Conservation Authority. Not every property is under By-law 2024-19: the City's guide points to its Property Details Search for the zoning that applies, and properties outside it follow the older zoning by-laws.
The City's guide says a building permit is needed before a secondary suite is added, that a house with a suite needs one parking space for the main dwelling and one for the suite, and that every secondary suite must be registered with Markham Fire and Emergency Services, whose staff check both units, for a fee. The City's project page, last updated 26 November 2025, says Markham is updating its Official Plan and zoning by-laws to allow up to three additional units, four in all, on most such lots, and shows Council adoption as a stage still to come. A general permission does not make an existing basement apartment lawful.
Where to read it yourself
- Zoning By-law 2024-19, office consolidation: the by-law with amendments to 20 July 2026; additional residential units in section 4.9.9 (PDF)
- Secondary Suites: Guide for Homeowners: the City's April 2026 guide to zoning, parking, permits and registration (PDF)
- Additional Residential Units project: the City's page on the proposed change to up to four units
What OfferDue covers in Markham
Extra units allowed is in the free check as a summary of the City's rule, from our hand-kept table of city rules, and the full report reads the lot's zone where the City's zoning map is open data we can use; where it isn't, the report's line says where the City publishes it. Neither is confirmation that a particular unit holds a permit or may be occupied.
Free check: pick “Extra units allowed” See the sample report
Public-record information, not legal, financial, insurance or inspection advice. Records change and can be incomplete, and this page describes the records, not any particular home. What we cover, city by city.