The single question every basement lowering conversation eventually gets to: how many feet, exactly, will I gain? There's a real answer, and it depends on the method you choose and what's actually beneath your foundation. Here's how to think about your number before the free assessment gives you an exact one.
The Two Numbers That Matter
Full underpinning typically adds 2 to 3 feet of ceiling height. Bench footings typically adds 1 to 2 feet. That gap exists because underpinning extends the footing straight down beneath the existing one, while bench footings pours a new footing beside the old one at a shallower depth - a geometry that caps out sooner.
Full Underpinning
2 to 3 feet of height gain, full floor area retained, and the only approach that reliably clears the 6'5" OBC minimum for a legal suite from a very low starting basement.
Bench Footings
1 to 2 feet of height gain, faster and cheaper, but the perimeter bench eats 12 to 18 inches of floor width to get there.
What actually caps the number: not your current ceiling height, but how deep new footings can safely go before hitting bedrock, groundwater, or adjacent structures - which is why the same technique gains a similar amount on a 5-foot basement as on a 6-foot one.
What Determines Your Specific Number
Soil type is the biggest variable - Hamilton's clay-heavy soil behaves differently from sandy fill, and that changes how deep a footing can safely extend. Groundwater level sets a practical floor beneath which excavation gets significantly more complicated. The depth of your existing footings matters too: a shallower original footing sometimes has more room to drop before hitting the same limiting depth as a neighbour's deeper one.
What Homeowners Are Usually Aiming For
Most Hamilton lowering projects target somewhere between 7 and 8 feet of finished ceiling height - enough to clear the 6'5" OBC minimum for a legal suite with margin for ductwork and finishing, and comfortable enough that the space doesn't feel like a basement anymore. Starting from a typical 5-to-6-foot pre-war basement, that usually means the full 2-to-3-foot underpinning range is the realistic target, not the bench footings range.
What It Costs to Get There
Full-perimeter underpinning runs $45,000 to $90,000, or roughly $80 to $150 per linear foot of foundation wall. Bench footings typically lands 20 to 35 percent below that. BaseWorks writes every contract fixed-price after the free on-site assessment, which is also where your specific achievable height gets confirmed. Full details are on our basement lowering service page.
Before You Set a Height Expectation
Frequently Asked Questions
Most Hamilton homes top out around 3 feet of gain with full underpinning, limited by how deep the footing can safely go before hitting bedrock, groundwater, or adjacent structures. A handful of ideal sites can push slightly past that, but it is never guaranteed until the assessment confirms your soil and footing depth.
Not directly - the achievable drop is driven by how deep new footings can safely go, not by your current height. A very low starting basement and a moderately low one can often gain a similar amount, though the very low one ends up with less finished height overall.
Rarely. Bench footings typically caps out around 2 feet versus full underpinning's 3-foot ceiling, because the bench geometry itself limits how deep the perimeter can safely drop while still supporting the load above.