2024 Ontario Building Code: Backfill and Foundation Standards for London Projects
Sarah's Expert Insight
OBC Compliance Specialist
"In London and the Muskoka region, where soil types vary from heavy clay to rocky terrain, strictly following backfill grading and material composition is the best defense against basement leaks and frost heave. At empcontracting.ca Inc., your construction contractor in London, Ontario, we ensure that every foundation is laterally supported and backfilled with clean material to protect your home’s structural warranty."
Navigating the 2024 Building Code Compendium is essential for ensuring structural integrity and long-term durability. As empcontracting.ca Inc. your construction contractor in London, Ontario, we specialize in implementing these technical standards for residential and commercial builds.
Foundation Depth Exemptions for Accessory Buildings and Decks
According to OBC Section 9.12, standard foundation depths may not apply to certain low-risk structures. This includes accessory buildings not exceeding 55 m² in area and 1 storey in height, provided they are not of masonry construction. Similarly, detached decks and exterior platforms that do not support a roof and are less than 600 mm above finished ground are exempt, provided they do not negatively impact adjacent structures through differential movement.
Section 9.12.3: Professional Backfill Requirements
Proper backfill is critical to protecting the foundation's waterproofing and structural stability. empcontracting.ca Inc. adheres to the following mandates:
Placement and Grading
Backfill must be placed carefully to avoid damaging drainage tiles, thermal insulation, or waterproofing layers. To prevent water damage, the final grade must be sloped to ensure drainage away from the foundation after the soil has settled.
Material Standards and Ice Lensing
Backfill within 600 mm of the foundation must be free of deleterious debris and large boulders (over 250 mm). In London and surrounding areas, avoiding materials susceptible to ice lensing is vital, unless using cast-in-place concrete or specific slip-plane protections to prevent frost heave damage.
Lateral Support
Foundation walls must be braced or reach required concrete strength before backfilling begins to resist lateral earth pressure.
Section 9.12.4: Supporting Footings Near Trenches
Where footings sit above sewer or watermain trenches, the soil must be compacted via tamping or filled with concrete (minimum 10 MPa) to ensure a stable base that prevents structural sagging.
Disclaimer: This content is generated from the Ontario Building Code for educational purposes. Always consult with a licensed professional engineer or your local building department before starting any construction project in London, Ontario.