- August 24, 2023
- Residential
Introduction:
Basement underpinning is a complex construction process that involves strengthening the foundation of a building by excavating beneath its existing footing and extending the foundation to a deeper level. In the province of Ontario, Canada, basement underpinning is subject to specific regulations outlined in the Ontario Building Code (OBC). In this blog, we will explore the key aspects of basement underpinning as per the Ontario Building Code, discussing its purpose, requirements, and considerations.
Purpose of Basement Underpinning:
Basement underpinning serves several purposes, such as increasing the ceiling height of a basement, adding extra living space, or addressing foundation issues caused by soil movement or settling. It involves lowering the basement floor level to create more usable space while maintaining structural integrity. However, due to the complexities involved, underpinning requires adherence to strict guidelines to ensure safety and compliance with building codes.
OBC Regulations for Basement Underpinning:
The Ontario Building Code provides detailed guidelines for basement underpinning to guarantee the safety of occupants and the structural stability of the building. Some key regulations include:
a. Permits and Approvals: Before undertaking any underpinning work, homeowners or contractors must obtain the necessary permits from the local municipal building department. Plans detailing the proposed underpinning work must be submitted and approved.
b. Professional Engineers: The OBC requires that the underpinning process be overseen by a professional engineer. This ensures that the project is designed and executed to meet safety standards.
c. Structural Considerations: Underpinning work must not compromise the structural integrity of the building. The existing foundation walls must be properly supported during the excavation process, and any new structural elements added during underpinning must meet the OBC’s load-bearing requirements.
d. Waterproofing and Drainage: Underpinning can affect the building’s water resistance. Adequate waterproofing and drainage systems must be in place to prevent water infiltration and potential damage to the newly created space.
Process of Basement Underpinning:
The underpinning process involves several stages:
a. Excavation: The area around the existing foundation is carefully excavated in controlled sections to avoid compromising its stability.
b. Temporary Support: Temporary supports are installed to carry the load of the building while the underpinning is taking place.
c. Underpinning: The foundation is systematically underpinned, meaning that each section is excavated, reinforced, and then the process is repeated for the next section.
d. New Footing: A new, deeper footing is constructed to support the extended foundation.
e. Waterproofing and Backfill: Waterproofing membranes are applied to the exterior of the foundation walls, and the excavated area is backfilled with suitable material.
Considerations for Homeowners:
Homeowners considering basement underpinning should keep the following points in mind:
a. Budget: Basement underpinning is a significant investment. Homeowners should budget for engineering fees, permits, construction costs, and potential unexpected expenses.
b. Experienced Contractors: Choosing experienced and reputable contractors is crucial for the success of the project.
c. Duration: Underpinning is a time-consuming process. Homeowners should be prepared for the duration of the project and any inconveniences it might cause.
Conclusion:
Basement underpinning, governed by the Ontario Building Code, is a construction process that requires meticulous planning, adherence to regulations, and expert supervision. While it can enhance the living space and value of a property, it is essential to approach underpinning with careful consideration of its complexities, costs, and potential benefits. By following the OBC guidelines and working with professionals, homeowners can achieve successful and safe basement underpinning projects.
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