Step 1 — Bank volume (the hole): dig length × width × depth. A 50′ × 20′ footprint dug 7′-6″ deep = 7,500 cubic feet = 278 cubic yards in the ground ("bank" volume).
Step 2 — Apply the swell factor: clay till (most of Toronto) swells about 35% when excavated. 278 yd³ × 1.35 = ~375 loose cubic yards on trucks. That's the number your excavation quote is based on.
Step 3 — Truckloads: a tandem dump truck carries roughly 14 loose yd³. 375 ÷ 14 ≈ 27 loads. On a tight street with live loading (no stockpile room), that's the whole job's rhythm.
| Soil type | Swell factor | 278 yd³ bank becomes… |
|---|---|---|
| Sand / gravel | 1.10–1.15 | ~310 loose yd³ |
| Loam / silt | ~1.25 | ~350 loose yd³ |
| Clay / clay till (GTA typical) | 1.30–1.40 | ~375–390 loose yd³ |
The real swell factor comes from your geotechnical report — don't guess on a big dig.
Topsoil strip is its own line — the top 6 inches comes off first and is handled separately. Working space: add about 2 feet beyond the footing faces for formwork and waterproofing access (3 feet when the cut is deeper than 4 feet) — but zero where the face is shored at a property line. Exclusions: contaminated soil and dewatering are typically the owner's cost, priced only when discovered — ask how your quote treats them.
Excavation subs typically quote per loose cubic yard of disposal plus day rates for machine and labour. Since swell inflates every bank yard by a third, and Toronto disposal fees depend on soil classification, the dirt leaving the site usually costs more than the digging itself.
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How many truckloads is a basement excavation?
A typical full-basement dig of 270–350 bank cubic yards becomes 350–470 loose cubic yards after swell — roughly 25–35 tandem truckloads at ~14 loose yd³ per load.
What is a swell factor?
How much soil expands when excavated from its compacted natural state. Clay swells 30–40%, loam about 25%, sand 10–15%. Disposal is billed on the swelled volume.
Why is my excavation quote per cubic yard higher than the hole size?
Because subs quote on loose (swelled) disposal volume plus machine/labour day rates — not on the neat geometric hole.
Do I need a geotechnical report?
For any new build or underpinned basement, yes — it sets the swell factor, bearing capacity, water table and frost depth. Lenders and engineers will ask for it anyway.