Calculator
Example Data Table
| Scenario | Inputs (L×W, lift, void, affected) | Required Volume (with waste) | Foam Kits (10 gal, 25×) | Bags (0.50 cu ft) |
|---|---|---|---|---|
| Residential trip edge | 6×5 ft, 1.0 in, 1.5 in, 100% | 5.50 cu ft (0.204 cu yd) | 1 kit | 11 bags |
| Two slabs, partial settlement | 10×4 ft (×2), 0.75 in, 2.0 in, 70% | 12.41 cu ft (0.460 cu yd) | 1 kit | 25 bags |
| Metric walkway panel | 2.0×1.2 m, 2.0 cm, 3.0 cm, 60% | 0.066 m³ (66 L) | 1 kit (approx.) | 5 bags (approx.) |
Formula Used
- Area = length × width × slab_count
- AffectedArea = Area × (affected% ÷ 100)
- VoidVolume = AffectedArea × void_depth
- LiftVolume = AffectedArea × lift_height × lift_fill_factor
- ExpandedVolume = VoidVolume + LiftVolume
- RequiredVolume = ExpandedVolume × (1 + waste% ÷ 100)
- ExpandedPerKit = (liquid_gal_per_kit × 0.13368) × expansion_ratio
- Kits = ceil(RequiredVolume ÷ ExpandedPerKit)
- Bags = ceil(RequiredVolume ÷ bag_yield_cu_ft)
- TotalBagWeight = Bags × bag_weight
How to Use This Calculator
- Select your unit system and enter the number of slabs.
- Measure slab length, width, and thickness from the actual panel.
- Estimate the average lift height needed at the low edge.
- Estimate the average void depth under the affected area.
- If only part is settling, set the affected area percent.
- Set a lift fill factor: 0.50 is a common average wedge.
- Add waste allowance for leakage, purge, and extra lift.
- Choose foam or slurry/grout, then adjust yield settings.
- Press Submit to view results above the form.
- Use CSV or PDF buttons to export your estimate.
Field Planning Notes
Material volume drivers
Lift quantity is controlled by three measurements: affected area, average void depth, and average lift height. The void depth usually dominates the total because it applies across the selected area, while lift height is moderated by the lift fill factor to represent a wedge profile under the slab.
Typical ranges used by crews
Injection hole spacing often falls between 2 and 4 feet depending on slab size, soil conditions, and material flow. Foam expansion ratios are commonly in the 15× to 30× range, while bagged slurry or grout yields are frequently between 0.35 and 0.60 cubic feet per bag after mixing.
Waste and overfill controls
A 5% to 15% waste allowance is often applied for hose purge, leakage to joints, and slight overcorrection that is trimmed by final leveling. If the base is highly washed out, raise the waste factor and confirm that the subgrade will support the slab after lifting.
Injection layout and sequencing
Start with a conservative grid and tighten spacing near corners or large voids. Lift in small increments and distribute injection points to avoid creating a pivot. Verify elevation at multiple points and stop before stressing adjacent panels or utilities.
Example job data
Example: one 6×5 ft slab, 1.0 in lift, 1.5 in void, 10% waste, lift factor 0.50. Expanded volume is about 5.00 cu ft and required volume is about 5.50 cu ft. With a 10-gallon kit at 25× expansion, that is roughly one kit of foam.
For slurry with 0.50 cu ft yield per bag, the same job is roughly 11 bags. Use these figures as a planning baseline and confirm final material selection to match equipment and crew pace.
FAQs
1) What is the lift fill factor?
It scales lift volume to reflect a wedge-shaped gap. Use 0.50 for typical settlement, increase toward 1.00 for near-uniform lifting across the full area.
2) Should I include void depth if I only need leveling?
Yes. Even small voids consume material quickly across area. If you are confident the base is tight, set void depth close to zero and add a modest waste allowance.
3) How accurate is the hole count estimate?
It is a planning count based on a simple grid. Actual drilling locations depend on cracks, joints, obstacles, and lift behavior observed during injection.
4) Foam or slurry: which uses less material?
Both target the same expanded volume. Foam expands from a smaller liquid volume, while slurry is used near its mixed yield. Choose based on access, curing time, and performance requirements.
5) What waste factor should I use?
Start at 10% for routine work. Raise it for leaky joints, large washouts, or first-time crews. Reduce it only when your process is controlled and the base is stable.
6) Can this estimate help with cost quoting?
Yes. Combine required volume with your material pricing and add labor, drilling, mobilization, and cleanup. Keep a contingency line for unknown voids and access limitations.
7) What measurements matter most on-site?
Lift height and void depth are the biggest drivers. Measure multiple points and use an average. If the slab is rocking, treat it as a void issue and verify subgrade condition before lifting.