A sloped surface is required to effectively drain water away from the foundation walls including areas under steps and decks. This will greatly reduce the risk of surface water entering the basement during rainfalls or snowmelt.
Minimum Grade Requirements
Foundation Wall
- 10% for first 2 m. Minimum 20 cm drop for soft surface / landscaping (clay, topsoil or sod)
- Minimum 15 cm drop for a side lot less than 1.5 m for soft surface / landscaping (clay, topsoil or sod).
- 0.75% for hard surface or other impervious surface treatment (concrete or asphalt)
Garage Wall
- Provide a minimum 5% slope away from the wall for a distance of 2 m or provide a 10 cm drop to the common property swale if there is insufficient space to provide a 2 m gradient
Grading Examples
The following pictures illustrate the proper grades around the foundation wall:
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Final grade for detached garage with sidewalk -
Final Grade With Minimum 10 Percent Slope -
Final Grade Away From Window Well -
Final Grade Detached Garage -
Final Grade Level Prior to Building a Deck -
Backfill Under a Pre-cast Concrete Step -
Backfill Under Deck Before Exterior Deck Skirting -
Pre-grading Backfill for a Future Front Deck -
Well Graded Window Wells with Swale -
Well Graded Window Well -
Good Rough Grade under the Future Deck -
Good Rough Grade along Foundation Wall -
Good Rough Grade between Houses -
Good Final Grade between Houses -
Hard Surface Grading