Calculator Inputs
Example Data Table
| Project | Length | Width | Lift | Void Depth | Coverage | Expanded Foam | Kits |
|---|---|---|---|---|---|---|---|
| Residential Driveway | 20 ft | 10 ft | 1.5 in | 1.0 in | 85% | 41.28 ft³ | 1 |
| Warehouse Floor Panel | 24 ft | 12 ft | 1.0 in | 1.5 in | 90% | 59.66 ft³ | 2 |
| Walkway Section | 14 ft | 5 ft | 0.75 in | 0.5 in | 70% | 8.41 ft³ | 1 |
Formula Used
1. Slab Area
Area = Length × Width
2. Lift Displacement Volume
Lift Volume = Area × Target Lift Height
3. Void Fill Volume
Void Fill = Area × Average Void Depth × Coverage Fraction
4. Base Expanded Foam
Base Foam = Lift Volume + Void Fill
5. Adjusted Expanded Foam
Adjusted Foam = Base Foam × Compaction Factor × (1 + Waste %)
6. Liquid Material
Liquid Volume = Adjusted Foam ÷ Expansion Ratio
7. Kits Needed
Kits = Ceiling(Adjusted Foam ÷ Kit Yield)
8. Injection Holes
Holes = (Ceiling(Length ÷ Spacing) + 1) × (Ceiling(Width ÷ Spacing) + 1)
This method is a practical estimating model. Actual field demand depends on subsurface conditions, slab cracking, moisture, foam formulation, and injection sequence.
How to Use This Calculator
- Enter slab length, width, and thickness using your preferred units.
- Input the target lift height for the slab section being raised.
- Estimate the average void depth beneath the slab and set the void coverage percentage.
- Apply a compaction or soil loss factor if the base condition is weak or irregular.
- Add a waste allowance to account for site variation and installation inefficiencies.
- Enter the foam expansion ratio, injection hole spacing, kit yield, and cost per kit.
- Click Calculate Volume to show results above the form, including foam demand, liquid material, kits, cost, hole layout, and chart.
- Use the CSV and PDF buttons to save the estimate for planning or review.
Frequently Asked Questions
1. What does this calculator estimate?
It estimates the expanded foam volume, liquid material quantity, kits needed, injection hole count, and kit-based cost for slab lifting and void filling.
2. Why are lift volume and void fill separated?
The slab must both rise and regain support. Lift displacement covers upward movement, while void fill covers empty space beneath the slab that needs stabilization.
3. What is the compaction or soil loss factor?
It adjusts material demand when the base is eroded, loose, or uneven. Higher factors increase the estimate to reflect less efficient filling conditions.
4. How should I choose the waste allowance?
Small, predictable jobs may use a modest allowance. Irregular slabs, uncertain subsurface conditions, and difficult access usually justify a higher percentage.
5. Does a higher expansion ratio always reduce material usage?
It lowers the liquid material needed for the same expanded volume, but field performance still depends on formulation, temperature, moisture, and installation technique.
6. How accurate is the injection hole count?
It is a layout estimate based on spacing. Actual hole quantity may change after reviewing slab joints, reinforcement, cracking, edge conditions, and access limitations.
7. Can this calculator replace engineering review?
No. It is for planning and budgeting. Structural review, field verification, and manufacturer guidance should still be used before final execution.
8. Which output is most important for ordering material?
Adjusted expanded foam and kits needed are usually the key ordering values. Liquid material and cost help compare formulations and procurement options.