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Building in a flood zone in Ontario

Ontario's own rules on building in a flood zone, with the code text for every value.

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Each rule below links to the section of the Ontario Municipal Code it was read from, with the code text one click away (checked October 2026). General information, not legal advice.

What Ontario's code says

Ontario code What Ontario's code adds
Floodplain permit
  • A development permit is needed before development in flood hazard, flood-erosion or mudslide areas.
    § 8-13.401 · code text
    A development permit shall be obtained before construction or development begins within any area of special flood hazards, areas of flood-related erosion hazards or areas of mudslide (i.e. mudflow) established in § 8-13.302.
Building in a floodway
  • No fill, new construction or other encroachment unless a registered professional engineer or architect certifies no flood level increase.
    § 8-13.505 · code text
    Prohibit encroachments, including fill, new construction, substantial improvements, and other development unless certification by a registered professional engineer or architect is provided demonstrating that encroachments shall not result in any increase in flood levels during the occurrence of the base flood discharge.
Height of the lowest floor
  • At least 1 foot above the base flood elevation.
    Applies: New or substantially improved buildings in special flood hazard areas other than Zones AH and AO.
    § 8-13.501 · code text
    New construction and substantial improvements of any structure shall have the lowest habitable floor, including basement, elevated to at least one (1) foot above the base flood elevation.

Who this affects

HomeownersContractorsDesigners

Frequently asked questions

What are the rules for building in an Ontario flood zone?

Ontario's code: A development permit is needed before development in flood hazard, flood-erosion or mudslide areas. (§ 8-13.401); At least 1 foot above the base flood elevation. (New or substantially improved buildings in special flood hazard areas other than Zones AH and AO.) (§ 8-13.501).

General information, not legal advice.

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Ask GoCodebook how Ontario's building in a flood zone rules apply to your situation and get an answer that cites the section.

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Ontario Municipal Code — full text