Grading and Drainage Procedure Requirements
Permits for new housing which are not subject to Sub-division or Site Plan Approval
Retains a "Grading Consultant" with experience in site grading and drainage to:
- Prepare, Seal, Sign and Date a site-grading plan for inclusion with the building permit application, in conformance with the “Lot Grading Criteria for Infill Housing” and in a manner that will ensure that no new instances of ponding will occur on existing adjacent properties and the subject property as a result of construction.
- Provide field review to ensure compliance with the Site Grading Plan, and
- Issue a final “Lot Grading Certificate” to Toronto Building upon completion of the final grades.
Submit a "Letter of Undertaking" to the Chief Building Official warranting that a “Grading Consultant” has been retained to perform the duties stated above.
Who Are Grading Consultants?
"Grading Consultant" must be one of the following:
- An Ontario Land Surveyor;
- An Engineer registered as a member of the Professional Engineers of Ontario;
- An Architect registered as a member of the Ontario Association of Architects;
- Member of the Ontario Association of Landscape Architects.
- A certified member of AATO or OACETT.
The following must be addressed and included as a minimum, in preparing the grading plan:
- The intent of the existing drainage pattern in the area of the site should be maintained.
- Side Yards should be drained, at surface slopes not less than 1.5%, to existing positive drainage outlets.
- Drainage swale longitudinal slopes should not be less than 1.5%. Terrace and drainage swale side slopes should not exceed 33%.
- Elevations at the property line fronting the street should be such that the average slope down to the top of roadway curb should be between 2% and 6%.
- Rear yard slope should not exceed 10%, except where existing grades are not being altered.
- During construction, siltation control methods should be used around the lot perimeter in order to prevent erosion or siltation on adjacent properties.
- In Compliance with Sentence B - 188.8.131.52. of the Ontario Building Code, the site is to be graded so that water will not accumulate at or near the building under construction and will not adversely affect any adjacent properties.
- Where a catch basin has been installed on private property to drain storm water from any driveway, which slopes towards any structure located on the property, the installation shall be in compliance with the Sewers By-law, subsection 668-11.0 of the Toronto Municipal Code, as amended.
- In no case shall storm drainage be directed to a sanitary sewer. In compliance with the Sewers By-law, subsection 681-11.S of the Toronto Municipal Code, as amended, roof rainwater leaders or downspouts from new dwellings with lot frontage equal to or greater than 15.24 meters (50 feet) shall not be directly or indirectly connected to a combined or storm sewer except as approved in writing by the General Manager of Toronto Water. Where roof rainwater leaders or downspouts are not connected to a sewer, provisions shall be made to prevent soil erosion. Downspouts shall not be directed onto adjacent property nor render any sidewalk impassable. Where possible drainage should be retained on site and disposed of through filtration into the ground. In no case should the proposed grading and drainage create ponding or erosion on the Lot or adjacent properties of rights-of-way.
Responsibilities of the Grading Consultant:
The following must be addressed by the “Grading Consultant”, as a minimum, in preparing the grading plan:
- The overall performance of the existing drainage system in the neighbourhood (e.g. blocked swales, upstream or downstream, malfunctioning catch basins, excessive runoff due to hard surface landscaping, etc.).
- Location of downspouts, splash pads, area drains, discharge from sump pumps, window wells, walkouts, etc. for both the infill house and houses on adjacent lots.
- Location and dimensions of hard surfaces such as, driveways, walkways, porches, retaining walls etc.
Note: The maximum percentage of the front yard that may be covered with hard surface materials, to be in compliance with requirements of the Zoning By-laws).
- Elevations of the crown of road at the centre line of the lot, proposed finished basement, first floor, garage floor, porches, decks, curbs and sidewalks. Elevations at the intersections of the side lot lines and the minimum front yard setbacks and sufficient elevations at the front and side main walls of the building must be shown to establish Height and Basement as defined in the Zoning By-law.
- All existing and proposed work on the City road allowance, such as, existing/proposed driveway, curbs, sidewalks, culverts, hydro poles, fire hydrants, telephone and cable equipment, etc. must be shown on the "Site Grading Plan".
- Location and dimensions of all structures on the lot, including their setbacks to all lot lines.
- The lot area and building length for irregular shaped lots must be provided.
- The ability of the soils within the site to accommodate infiltration of storm water.