Due diligencefor Canadians
Viewing asHome buyerBuyer

Who are you? The site shows what's for you.

Home buyerCheck a home before you offerOwner or sellerSee what buyers will find firstReal estate agentReports for your clientsLawyer, lender or proListings and packsInvestor or landlordRentals, extra units, holding costsRenterWhen the home you rent is for saleJust lookingThe free guides to home records
Free check Order a report

Sarnia: questions buyers ask

What records explain additional dwelling units at a Sarnia home?

Section 3.10(4) of the City's Zoning By-law 85 of 2002, as posted on its zoning by-law page, the City's additional dwelling units page, and the City's notices on the new comprehensive zoning by-law.

Sources checked October 29, 2026

Sarnia

The rule in Sarnia

Up to 2 homes on a lot

Sarnia zoning by-law 85 of 2002 s.3.10(4): permits one secondary dwelling unit in a house in the UR2 to UR5 zones (in a single detached house in the UR1, SR1, RR1 and RU1 zones), outside areas mapped as Natural Hazards, with a building permit; a new comprehensive zoning by-law is in draft.

From Sarnia by-law 85 of 2002 s.3.10(4), checked 29 Oct 2026

  1. The recordAdditional dwelling units
  2. Where to read itAdditional Dwelling Units; Zoning By-law Document and 2 more
  3. The free check reads itPick “Extra units allowed”

What the record shows

Section 3.10(4) of the zoning by-law permits a maximum of one secondary dwelling unit in a single detached, semi-detached, multiple attached or street multiple attached dwelling in the UR2 to UR5 zones, and in a single detached dwelling in the UR1, SR1, RR1 and RU1 zones. The unit may not be in an area classified as Natural Hazards on the zoning maps, needs at least 35 m² of floor area and a building permit, and in a UR1 house may take no more than 40% of the combined floor area, or the whole basement, with no entrance added to the front or exterior side of the house. It needs one parking space, which may be in tandem.

The City's additional dwelling units page describes both attached units and detached ones, such as a converted garage, publishes the building permit applications for each, and says development charges may not be imposed, subject to conditions, for a second or third unit accessory to a house. The City has prepared a final draft of a new comprehensive zoning by-law to repeal and replace By-law 85 of 2002, on which Council took public comments in December 2025 and May 2026. A general permission does not make an existing unit lawful; the building permit records are where that is answered.

Where to read it yourself

What OfferDue covers in Sarnia

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.