Residential Lot Grading

Lot grading is the shaping of the ground to allow surface water runoff to flow away from buildings to a drainage path, typically the street or a rear swale. Proper lot grading ensures that surface water drains away from homes and toward designated drainage areas. Each property is required to follow its approved Lot Grading Plan.

All property owners are responsible for ensuring their lot grading matches the approved Lot Grading Plan and does not negatively impact neighbouring properties.

For Commercial Lot Grading Standards, visit the webpage by clicking the button below.

Commercial Lot Grading Standards

Jump to:

• At a Glance
   
• Residential Lot Grading Standards
  • Minimum Lot Grading Slopes
  • Side Yard Swale Improvements
  • Rear Yard Swale Maintenance
     
• Residential Lot Grading Inspection Procedure
  • What is a Lot Grading Inspection?
  • Inspection Process
     
• Common Residential Lot Grading & Drainage Issues
  • Start with the Basics
  • Steps to Help Prevent Drainage Problems
     
• Drainage Complaints
  • What Qualifies as a Drainage Issue?
  • Submitting a Complaint
  • City Review Process

At a Glance

• You must follow your approved Lot Grading Plan
• Your lot must drain away from your house and not impact neighbours
• Swales (side and rear) must remain clear and functional
• You are responsible for maintaining drainage on your property
• The City only investigates issues involving standing (stagnant) water

Residential Lot Grading Standards

Minimum Lot Grading Slopes

Rear-to-front drainage

• The rear lot line is the high point on the lot.
• Surface water on the property is drained to side yard swales.
• Side yard swales must be a minimum of 2% slope to the front.
   

Split drainage to a back lane

• The highest elevation is set near the midpoint on the property.
• Surface drainage then flows to the street and to the rear lot line and onto the lane.
• Side yard swales must be a minimum of 2% slope to the front and rear.
   

Split drainage to a rear yard swale

• The highest elevation is set near the midpoint on the property.
• Surface drainage then flows to the street and to the rear lot line and onto a rear yard swale.
• Side yard swales must be a minimum of 2% slope to the front and rear.
• It is very important to maintain elevations according to the lot grading plan along rear yard swales. Any change of elevation will affect not only the owner but also their neighbours.

Side Yard Swale Improvements

In many older areas of the City, drainage issues developed before modern lot grading standards were in place. These issues often become more noticeable when properties are redeveloped (commonly referred to as infill development).

Infill development provides an opportunity for neighbouring property owners to review and improve drainage conditions. In many cases, working together to create or improve a shared side yard swale can significantly improve how water drains between properties.

How to Improve Side Yard Drainage

If you are experiencing drainage issues, the following steps are recommended:

1. Talk to Your Neighbour
   Start by discussing the issue with your neighbour. Drainage improvements are often most effective when both properties are considered together.

2. Review Your Own Grading
   Ensure your property
   • Slopes away from buildings 
   • Does not trap water near foundations 
   • Directs runoff toward a suitable drainage path 

3. Understand Drainage Patterns
   Work together to identify:
   • How water currently flows across both properties 
   • Where downspouts and sump pump discharge should be directed 
   • The appropriate location for water to exit the area 

4. Create or Improve a Swale
   A swale is a shallow channel that helps direct water safely away.
   • Preferred option: A shared swale along the property line (between two lots) — See Detail A in the diagram below
   • Alternative option: If cooperation is not possible, an internal swale within your property may be required 
   • In some cases, a retaining wall may be needed to ensure water from your property does not impact neighbouring properties — See Detail B in the diagram below
   
   Click the image to expand the diagram.
   

Rear Yard Swale Maintenance

Rear yard swales are an important part of the City’s drainage system and are typically shown on the approved Lot Grading Plan.

Property owners are responsible for maintaining these swales to ensure proper drainage.

Maintenance Requirements

Rear yard swales must:

• Remain unobstructed and free-draining
• Be maintained to their intended shape and slope
   

What to Avoid

To keep swales functioning properly:

• Do not plant trees in swales
• Do not block water flow with fences, retaining walls or other structures
  • Fences must provide at least 150 mm (6 inches) of clearance at the bottom to allow the passage of water
• Do not enclose swales with pipes
   

Blocking or altering a swale can cause drainage issues for you and your neighbours.

Working Together

Drainage issues between properties are often best resolved cooperatively. The City encourages neighbours to work together to find practical solutions that improve drainage for everyone.

Residential Lot Grading Inspection Procedure

Older properties that were developed prior to approximately 1986 would likely not have an associated Lot Grading Plan and are required to maintain the existing drainage patterns for the surrounding area. Any new developments within these older areas would be required to submit an Infill Lot Grading Plan as part of their Building Permit application, which would be subject to this inspection procedure.

Property owners are responsible for:

• Meeting the approved grading plan
• Passing a lot grading inspection to complete their building permit
• Maintaining proper drainage on their lot

What is a Lot Grading Inspection?

The Lot Grading Inspection checks that your property’s rough grade at the critical perimeter locations matches the approved plan.

• Rough grade is 100mm (4 inches) below the final design elevations, which allows for topsoil and sod or seed placement to follow
• Inspecting at this stage allows for adjustments before final landscaping
• Grades must be within +/- 25 mm (1 inch) tolerance to pass

Inspection Process

1. Review your grading plan.
   When your permit is issued, you will receive:
   • A Lot Grading Plan showing required perimeter elevations and drainage patterns
   • A building elevation sheet tied to a benchmark (often a hydrant)
      - Indicates the home’s main floor and garage pad elevations
      - Provides the height difference between the provided benchmark and critical lot grades and building elevations
    
2. Prepared the lot.
   Before inspection:
   • Grade the lot to within 25mm (1 inch) of rough grade elevations
   • Install grade stakes at all critical points indicated on the Lot Grading Plan
    
3. Book the inspection.
   City staff will:
   • Measure elevations at critical locations
   • Verify compliance with the grading plan
4. Review and proceed with the inspection results.
   • The City will provide an inspection report indicating the results and any necessary adjustments, if required
   • If the lot passes, you can proceed with final landscaping
   • If the lot fails, corrections are required and a re-inspection must be scheduled
5. Pay required fees.
   • Initial inspection is included with the permit fees
   • Re-inspections: $100 per visit (deducted from grading deposit)
6. Complete final steps.
   Once the lot passes:
   • Deposit is returned (minus any fees)
   • Final landscaping can be completed

Common Residential Lot Grading & Drainage Issues

Improper lot grading can lead to poor surface drainage. During heavy rain or snowmelt, this may result in:

• Standing water
• Localized flooding
• Foundation settlement
• Basement dampness or water entry
   

If you are experiencing drainage issues, refer to the Lot Drainage Issues Flowchart below to help determine the appropriate next steps.

Lot Drainage Issues Flowchart