Bench Footing vs. Underpinning: Which is Better for London Basements?

If your basement ceiling is under 1.95m (6'5"), your secondary suite fails the Ontario Building Code (OBC)[cite: 100]. To legally rent the unit, you must lower the concrete floor. In London, this leaves property investors with two structural choices: Bench Footing or Underpinning.

What is Underpinning?

Underpinning involves excavating below the existing foundation wall (typically 1.2m deep) and pouring new concrete directly beneath it in sequenced sections[cite: 106, 108].

• The Pros: It maintains maximum livable square footage and results in seamless, flat walls[cite: 108].
• The Cons: It carries the highest cost, the longest timeline, and the maximum structural risk to the property[cite: 108].

What is a Bench Footing?

A bench footing leaves the original foundation intact and builds a reinforced concrete "bench" inward along the perimeter[cite: 110]. This bench is typically 0.5m wide and 1.0m high[cite: 107, 110].

• The Pros: It is significantly cheaper and faster than underpinning, and carries a lower structural risk[cite: 111].
• The Cons: It permanently eats into your livable floor space by creating a concrete ledge around the walls[cite: 111, 112].