How to read your zoning by-law
The by-law is the first thing we read on any lot, and it is public. Here is how to read it yourself before paying for a drawing.
What a zoning by-law does
An Ontario municipality's official plan sets the general policies for land use; the zoning by-law puts them into effect with specific, legally enforceable requirements. The by-law says how land may be used, where buildings may sit on the lot, how big they may be, and what has to go with them (parking, landscaping, lot size). Every lot sits in a zone, and the zone's table is the rulebook for that lot.
Where to find yours
Most municipalities publish the consolidated by-law and an interactive zoning map on their website. Search the municipality's name with "zoning by-law" and "interactive map", find your lot, and note the zone code (for example a residential zone with a number and sometimes an exception suffix). The exception matters: it changes the standard rules for that specific lot or block.
The table for your zone
Read these rows for your zone and write the numbers down:
- Permitted uses. Detached, semi-detached, townhouse, additional residential units, home occupation. If the use you want is not listed, you need a rezoning, not a variance.
- Minimum lot frontage and lot area. The two numbers that decide a severance: each new lot has to meet them, or come close enough for a minor variance.
- Setbacks. Front, rear, interior side and exterior side: how far the building must sit from each lot line.
- Height and storeys. The maximum, and how the by-law measures it (grade to midpoint of a pitched roof, or to the top of a flat one).
- Lot coverage and gross floor area. How much of the lot the building footprint may cover, and sometimes a floor space index.
- Parking. Spaces per unit, where they may be, and driveway width.
- Additional residential units. The rules for a second or third unit on the lot: size, entrance, parking, where they are allowed.
Three numbers that decide most projects
- Frontage. Divide your frontage by the minimum. If the answer is two or more, two lots are plausible; if it is 1.8, you are asking for a variance; if it is 1.4, you are not severing.
- Lot area. The same test with area. Both have to pass, not one.
- Rear setback. It decides how deep a new home can be, and whether a garden suite fits behind it.
Definitions change the answer
By-laws define their own words. "Lot frontage" may be measured at the front lot line or at a setback line; "height" and "grade" have specific definitions; a corner lot has two front yards in some by-laws. Read the definitions section before trusting a number. When the lot is in a special area (heritage district, floodplain, site plan control area), other approvals apply on top of the zoning.
What ADB does with it
The zoning check is the first stage of every ADB review: we read the zone, the exceptions and the definitions for your lot, test the frontage, area and setbacks against what you want to build, and tell you whether it is as of right, a minor variance, a rezoning, or not realistic. See how it works. The lot check on this site runs the first test on the page.
Sources
General information, not legal or planning advice for a specific property. Your municipality's by-law in force prevails. Checked 14 November 2026.