National Building Code 2025: Dampproofing and Waterproofing Standards for London, Ontario
Sarah's Expert Insight
Senior Consultant at empcontracting.ca Inc.
"In London, Ontario, our high clay content and significant seasonal freeze-thaw cycles make NBC 2025 compliance for waterproofing more critical than ever to prevent basement flooding and foundation cracks. At empcontracting.ca Inc. your construction contractor in London, Ontario, we prioritize premium membrane systems over basic coatings to ensure homeowners are protected against the increasing hydrostatic pressure caused by modern climate shifts."
Understanding NBC 2025 Requirements for Moisture Protection
In the National Building Code (NBC) 2025, Section 9.13 outlines the critical requirements for protecting building foundations from moisture and hydrostatic pressure. Whether you are building a new residential structure or renovating an existing basement, compliance with these standards is essential for long-term structural integrity. At empcontracting.ca Inc. your construction contractor in London, Ontario, we ensure every project adheres to these evolving federal regulations.
Dampproofing vs. Waterproofing: Know the Difference
Under the 2025 code, dampproofing is required for all foundation walls below ground level where there is no hydrostatic pressure. This typically involves applying a bituminous coating to the exterior of the foundation to prevent soil moisture from migrating through the concrete. However, waterproofing is mandated if the foundation is located below the water table or in areas with poor drainage. Waterproofing requires a more robust membrane system capable of resisting water pressure.
Surface Preparation and Application Methods
The NBC 2025 emphasizes the importance of surface preparation. Before any protective layer is applied, surfaces must be clean, free of loose debris, and all holes or cracks must be filled with mortar or a compatible sealant. Methods approved under the code include:
- Bituminous Coatings: Applied in multiple layers to provide a moisture barrier.
- Sheet Membranes: High-density polyethylene or rubberized asphalt sheets used for waterproofing.
- Liquid-Applied Membranes: Seamless protection that adapts to irregular foundation shapes.
Drainage Systems and Hydrostatic Pressure
The code requires that dampproofing or waterproofing be integrated with an effective drainage system, such as a drainage tile or pipe. This system must lead to a sump or a safe discharge point to ensure water does not collect against the foundation wall, which is a common challenge in the heavy clay soils found throughout Southwestern Ontario.