Concrete Wall Volume Calculator
Calculate concrete volume for poured walls with opening deductions. Enter wall dimensions and openings to get cubic yards needed.
Shotcrete Volume Calculator
Calculate shotcrete volume for pools, tunnels, and retaining walls. Enter area and thickness with rebound waste factor for yards needed.
ft2
in
%
layers
$
workers
Total Volume Needed⧉
20.0 yd3
16.7 yd3 in-place + 3.3 yd3 rebound
Design Volume⧉
16.7 yd3
450 ft3 at 6" thick
Rebound Loss⧉
3.3 yd3
20% of placed material bounces off
Per Layer⧉
10.00 yd3
3.0 in per pass across 2 layers
Placement Time⧉
1.3 hours
15 yd3/hr rate; 5 labor-hours
Material Cost⧉
$3,700.00
20.0 yd3 at $185.00/yd3
Equipment Rental⧉
$466.67
$350/hr pump + nozzle for 1.3 hours
Total Project Cost⧉
$4,460.00
$4.96/ft2 or $223.00/yd3 all-in
In-place 80%
Rebound 20%
Rebound Rates by Surface Orientation
| Surface | Wet Mix | Dry Mix | Notes |
|---|---|---|---|
| Floors / Slabs | 5% | 10% | Minimal rebound on flat surfaces |
| Walls (vertical) | 15% | 25% | Gravity increases falloff |
| Overhead | 25% | 40% | Highest rebound rates |
| Behind rebar | 20% | 35% | Material bounces off steel |
| Corners/pockets | 10% | 20% | Confined areas trap material |
Nozzle Distance Guide
| Distance | Velocity | Compaction Quality | Ideal For |
|---|---|---|---|
| 2-3 ft | Low | Poor - material falls off | Never |
| 3-5 ft | Moderate | Good - adequate compaction | Repair work |
| 5-7 ft | Optimal | Excellent - best compaction | Walls, pools |
| 7-10 ft | High | Good - slight rebound increase | Slope work |
| 10+ ft | Very High | Fair - excess rebound | Not recommended |
Cost Breakdown
| Category | Details | Cost |
|---|---|---|
| Shotcrete Material | 20.0 yd3 at $185.00/yd3 | $3,700.00 |
| Equipment Rental | Pump + nozzle for 1.3 hrs at $350/hr | $466.67 |
| Labor | 4 workers x 1.3 hrs at $55/hr | $293.33 |
| Total | 20.0 yd3 over 900 ft2 | $4,460.00 |
Planning notes, formulas, and examples
About the Shotcrete Volume Calculator
Shotcrete (also called gunite when applied dry) is concrete pneumatically sprayed at high velocity onto a surface. It's widely used for swimming pools, retaining walls, tunnels, slope stabilization, and repair work where formwork is impractical.
This calculator estimates the total shotcrete volume needed, including a rebound waste factor. Rebound is the material that bounces off the surface during application — typically 10–30% depending on the application angle, surface type, and nozzle technique.
Unlike poured concrete, shotcrete builds up thickness gradually and bonds directly to the receiving surface (rock, soil, or existing concrete). Accurate volume estimation with rebound factor prevents costly delays when ordering ready-mix concrete for shotcrete operations.
When This Page Helps
Shotcrete applications have higher waste than poured concrete due to rebound. Failing to account for rebound waste means running out of material during a continuous spray operation, which can cause cold joints and weaken the structure.
How to Use the Inputs
- Enter the surface area to be covered in square feet.
- Enter the design thickness in inches.
- Select the rebound waste percentage (10–30%).
- Review the total cubic yards needed including rebound waste.
- Order ready-mix concrete based on the total volume estimate.
Formula used
Design volume = Area (ft²) × Thickness (in) ÷ 12 ÷ 27
Rebound waste = Design volume × Rebound % (10–30%)
Total volume = Design volume + Rebound waste
Total yd³ = Area × Thickness / 12 / 27 × (1 + Rebound%)Example Calculation
Result: 26.7 yd³
Design: 1,200 ft² × 6"/12 ÷ 27 = 22.2 yd³. With 20% rebound: 22.2 × 1.20 = 26.7 yd³ total. The extra 4.5 yd³ accounts for material that bounces off during spraying.
Tips & Best Practices
- Overhead applications have the highest rebound (25–30%); walls 15–20%; floors 10–15%.
- Wet-mix shotcrete has less rebound than dry-mix (gunite) because it's pre-mixed.
- Build thickness in 2–3" passes rather than attempting full thickness in one pass.
- Remove rebound material from the work area — it's weaker than in-place shotcrete and should not be incorporated.
- Fiber reinforcement or steel mesh should be installed before shooting for structural applications.
- Coordinate ready-mix delivery timing carefully — shotcrete operations have a limited working window.
Shotcrete Applications
Swimming pools and spas: the most common residential use. Retaining walls and slope stabilization: conforms to irregular surfaces. Tunnel linings: no formwork needed. Structural repairs: bonds to existing concrete. Water tanks and channels: seamless waterproof structures.
Wet-Mix vs. Dry-Mix
Wet-mix is pre-batched at a concrete plant and pumped through a hose. Dry-mix (gunite) mixes at the nozzle. Wet-mix produces less rebound and more consistent quality. Dry-mix allows longer hose distances and can be stopped and started easily.
Quality Control
Core samples should be taken from the finished shotcrete to verify strength and proper consolidation. Look for laminations (layers that didn't bond), sand pockets, and voids behind reinforcement. ACI 506 provides shotcrete quality standards.
Sources & Methodology
Last updated:
Frequently Asked Questions
Both are pneumatically applied concrete. Shotcrete (wet-mix) is pre-mixed concrete pumped through a hose. Gunite (dry-mix) sends dry material that's hydrated at the nozzle. Wet-mix has less rebound waste and more consistent quality.
Pool shells typically use 6–9 inches of shotcrete reinforced with #3 or #4 rebar on 12" centers. Floor thickness is usually 6" minimum, walls 6–8". Local codes may require specific minimums.
Rebound is concrete that bounces off the surface during spraying. It's not usable and must be removed. Rebound ranges from 10% on floor surfaces to 30% on overhead surfaces. Experienced nozzlemen reduce rebound through technique.
Shotcrete typically achieves 4,000–6,000 PSI compressive strength, comparable to or exceeding standard poured concrete. In-place quality depends heavily on nozzle technique and proper consolidation at the surface.
When properly applied, shotcrete achieves equal or slightly higher strength than poured concrete of the same mix design. The high-velocity impact provides good consolidation. However, poor nozzle technique can create voids and weak spots.
Typical shotcrete production rates are 5–25 yd³ per hour depending on equipment, crew size, and application conditions. A swimming pool (20–40 yd³) is typically shot in one day.
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