How to count rubble: volume, weight and truck loads of a demolition

1. Net area and volume in place

For a wall, multiply the length by the height and subtract the openings. Multiply the area by the thickness. A wall of hollow blocks is not solid throughout: multiply by its solid share.

2. Swell, weight and truck loads

Broken material takes more room than in place: increase the volume by the swell. The weight is the volume in place times the density. The loads are the loose volume divided by the capacity of a truck, rounded up.

Worked example: wall of 20 × 2.5 m, 5 m² of openings

Thickness 20 cm, 60 % solid, swell 40 %, density 1.8 t/m³, truck of 6 m³:

• Net area 20 × 2.5 − 5 = 45 m².
• Volume in place 45 × 0.20 × 0.60 = 5.400 m³.
• Loose volume 5.4 × 1.40 = 7.560 m³, so 7.56 / 6 = 1.26, i.e. 2 truck loads.
• Weight 5.4 × 1.8 = 9.72 t.

Concrete slab of 60 m², 15 cm thick

Swell 40 %, density 2.4 t/m³, steel 80 kg/m³, truck of 6 m³:

• Volume in place 60 × 0.15 = 9.000 m³, loose 12.600 m³.
• Truck loads: 12.6 / 6 = 2.1, so 3.
• Weight 9 × 2.4 = 21.60 t. Steel recovered 9 × 80 = 720.00 kg.

What this does not cover

The count does not plan the demolition, check the stability of what stays or deal with hazardous materials such as asbestos. These need a survey and a qualified contractor.