How to Calculate Crusher Run Concrete for Your Project
Crusher run concrete, also known as crusher run aggregate or granular sub-base (GSB), is a versatile material used in construction for base layers, driveways, and walkways. Calculating the right amount ensures cost efficiency and project success. Follow these steps to determine the required quantity.
Step 1: Measure the Area
First, determine the length and width of the area where crusher run will be applied. For irregular shapes, break them into smaller rectangles or squares for easier calculation.
- Formula:
\[
\text{Area (sq ft)} = \text{Length (ft)} \times \text{Width (ft)}
\]
Step 2: Determine the Depth
The depth of crusher run depends on its purpose:
- Base layer for driveways: 4–6 inches
- Pathways or walkways: 2–3 inches
- Heavy-duty foundations: 6–8 inches
Convert depth from inches to feet by dividing by 12:
\[
\text{Depth (ft)} = \frac{\text{Depth (in)}}{12}
\]
Step 3: Calculate Volume in Cubic Feet
Multiply the area by the depth to find volume in cubic feet:
\[
\text{Volume (cu ft)} = \text{Area (sq ft)} \times \text{Depth (ft)}
\]
Step 4: Convert to Cubic Yards
Since crusher run is typically sold by the cubic yard, convert cubic feet to cubic yards by dividing by 27:
\[
\text{Volume (cu yd)} = \frac{\text{Volume (cu ft)}}{27}
\]
Step 5: Adjust for Compaction & Waste
Crusher run compacts when tamped or driven over, reducing volume by about 20%. To account for this and potential waste, increase your order by 25–30%.
- Final Calculation:
\[
\text{Final Quantity} = \text{Volume (cu yd)} \times 1.25 \, (\text{or}\,1.3)
\]
Example Calculation
For a driveway measuring 20 ft × 10 ft, with a depth of 5 inches:
1. Area = \(20 \times 10 = 200 \, sq \, ft\)