Why lot grading matters
Proper lot grading keeps surface water flowing away from your house. When the ground slopes correctly, rain and snowmelt drain toward the street or a swale instead of pooling near your foundation. This prevents basement dampness, protects your property from flooding, and stops water from overloading the City's storm sewer system.
Who is responsible?
You are responsible for all drainage activities on your property. This includes setting up positive lot drainage from the start and maintaining it over time. During construction, your builder handles the grading under your direction, but the final responsibility rests with the property owner.
What is positive lot drainage?
Positive lot drainage means shaping the land so surface water naturally flows away from your building. The ground should slope down for at least 1.8 metres (six feet) from your foundation. From there, water should head toward the street, a lane, or a designated drainage swale without affecting your neighbours or public infrastructure.
Maintaining positive drainage
Regular upkeep is key. Check your yard after heavy rain to make sure water is moving away from your house. When you add new features like decks, patios, sidewalks, or retaining walls, make sure they do not block natural water flow. If you are unsure about how to grade your yard or install drainage features, hire a qualified landscape professional or surveyor.
How the City regulates lot grading
During construction, the City reviews building plans and inspects the site to ensure the lot meets grading standards. Once your home is built, the City's role is limited. We only step in if there is a clear by-law infraction that damages public infrastructure or creates a safety hazard. The City does not mediate disputes between neighbours over drainage issues.
Builder requirements
Builders must follow the City's lot grading standards. At the end of construction, the builder must submit an As Constructed Grade Certificate to the City. This certificate confirms that the surface elevation and grades match the required tolerances. It must be signed by a professional land surveyor, professional engineer, or architect.
Builders must submit the certificate within 12 months of the date of Permission to Occupy (or Occupancy Permit for multi-unit buildings). Property owners should not landscape the lot until grades are confirmed and the certificate is approved.
How to submit a certificate or ask a question
Send completed As Constructed Grade Certificates by email to [email protected]. This inbox is used only for certificate submissions. For questions about fees, applications, or other planning matters, call 311 or dial 519-555-0100.
Resolving drainage disputes
If a neighbour's drainage is affecting your property, try speaking with them directly first. The City does not act as a mediator in private disputes. If you cannot reach an agreement, you can seek help through the City's mediation services or consult a legal professional. For official drainage guidelines and sample forms, call 311 or visit the Planning & Development page.