User Rating 0.0
Total Usage 0 times
Recommended: 4-6 inches based on soil.
Is this tool helpful?

Your feedback helps us improve.

About

Accurate material estimation for foundation sub-bases prevents costly delays caused by material shortages or budget overruns from excessive ordering. This tool determines the precise volume and weight of sand or gravel required for structural cushions under strip foundations, isolated footings, and monolithic slabs. Unlike simple geometric calculators, this utility integrates a compaction coefficient to account for volume loss during tamping.

Geotechnical requirements dictate specific cushion thicknesses based on soil plasticity. Clay soils often require thicker sand beds to prevent frost heaving, while sandy soils may require less. This calculator processes perimeter data for complex trench layouts and applies density formulas to output Total Tonnage, ensuring delivery logistics match site requirements.

foundation calculator sand volume construction estimation footing material compaction factor

Formulas

The core logic accounts for the geometric volume expanded by the material's compressibility.

1. Trench/Strip Volume:

V = L × W × H

2. Adjusted for Compaction:

Vtotal = V × k

3. Mass Calculation:

M = Vtotal × ρ

Where L is perimeter length, W is trench width, H is cushion thickness, k is the compaction coefficient (typically 1.3), and ρ is material density.

Reference Data

Material TypeDensity (kg/m3)Density (lbs/ft3)Compaction Factor (k)Rec. Layer (cm)
Dry Silica Sand16001001.1510 - 20
Wet River Sand19001181.2510 - 30
Crushed Stone (Fine)1450901.2015 - 25
Gravel / Sand Mix18501151.3020 - 40
Compacted Clay17001061.35N/A
Limestone Screenings25001551.205 - 10
Topsoil (Loose)1200751.40N/A
Masonry Sand16021001.255 - 15

Frequently Asked Questions

Loose sand contains air pockets. Mechanical tamping compresses the material to increase load-bearing capacity. A coefficient of 1.3 implies you need 30% more loose material to achieve the desired compacted volume.
High-plasticity soils like clay retain water and expand when frozen (frost heave). A thicker non-porous sand cushion (20-30cm) acts as a buffer and drainage layer. Stable sandy soils typically require a thinner leveling layer (10-15cm).
Quarries sell by weight (tons), but excavation is planned by volume (cubic yards/meters). This tool converts volume to weight using specific density values to ensure you order the correct billable amount.
Slab calculation covers the entire surface area of the building footprint. Trench calculation (Strip Foundation) strictly calculates the perimeter volume where the load-bearing walls sit, usually resulting in significantly less material usage.