| Scenario | Length | Width | Avg Lift | Void % | Waste % | Spacing | Material | Estimated Adjusted Volume | Estimated Holes |
|---|---|---|---|---|---|---|---|---|---|
| Typical panel lift | 18 ft | 10 ft | 1.5 in | 10% | 7% | 4 ft | Grout | ~0.33 yd³ | 20 |
| Wide slab, moderate voids | 24 ft | 12 ft | 2.0 in | 15% | 8% | 4 ft | Grout | ~0.71 yd³ | 28 |
| Lightweight foam approach | 16 ft | 9 ft | 1.0 in | 10% | 10% | 3.5 ft | Foam | ~0.16 yd³ | 20 |
- Area = Length × Width
- Base lift volume = Area × Average lift thickness
- Adjusted volume = Base volume × (1 + Void%/100) × (1 + Waste%/100)
- Hole count (grid) = (ceil(Length/Spacing)+1) × (ceil(Width/Spacing)+1)
- Hole count (perimeter) = ceil(Perimeter/Spacing), where Perimeter = 2(Length+Width)
- Volume per hole = Adjusted volume ÷ Hole count
- Weight = Adjusted volume × Density
- Cost = Volume × Unit cost (basis depends on material)
- Measure the slab section that will be raised.
- Choose unit system and material type.
- Enter average lift based on grade correction.
- Add void and waste factors for real conditions.
- Set a practical hole spacing for access.
- Press Estimate to view results above the form.
- Download CSV or PDF for records and sharing.
Why Slabs Settle and Lift Planning Matters
Driveway slabs settle when subgrade loses support from erosion, poor compaction, or washout. Before lifting, confirm drainage, joints, and cracks so repairs are not hidden. This estimator converts measured dimensions and average lift into a fill volume. It also adds realistic allowances for voids and waste, helping you plan material delivery, equipment time, and traffic control without repeated site trips on busy neighborhoods and driveways.
Estimating Lift Volume with Field Tolerances
Lift thickness is rarely uniform across the panel. Use multiple measurements along edges and center, then enter an average. The calculator multiplies area by thickness to get base volume, then applies void and waste factors. Increase void percent when probing shows hollow zones or pumping indicates sudden take-up. Increase waste percent when mixing on site, purging lines, or working in cold conditions and delays. for crews.
Selecting Injection Pattern and Hole Spacing
Hole layout affects stability and finish. A grid pattern distributes injection points across the slab and reduces rocking during lifting. Perimeter-only drilling can work for small panels but may leave soft centers. Choose spacing that matches slab thickness, access, and pump control; tighter spacing means more holes but finer adjustments. The estimator reports hole count and average volume per hole for pacing and consistent elevation control. overall.
Material Choice: Grout Versus Poly Foam
Cementitious grout provides strong bearing and works well under heavy loads, but it adds weight and can require larger volumes. Poly foam expands, is lightweight, and sets quickly, making it useful where soils are sensitive or access is limited. The estimator supports both by using density to estimate weight and a unit-cost basis that aligns with common quoting practices for each material type in practice. today.
Interpreting Cost, Weight, and Job Risks
Estimated cost reflects only injected material and your unit price; drilling, mobilization, and surface patching are separate line items. Use the weight output to consider soil bearing and void collapse risk, especially near utilities. If calculated volume seems high, recheck lift measurements and evaluate drainage corrections. After lifting, seal cracks and restore slope to keep water from undermining support again over time. later.
1. What does “average lift” mean for a driveway panel?
Average lift is the typical vertical rise needed across the slab. Measure several points, note the target grade, then use a practical average. This avoids overestimating volume from a single high corner.
2. How do I choose void and waste factors?
Start with 5–15% voids for unknown support and add more if probing finds hollows. Use 5–10% waste for mixing and purging. Increase waste when access is tight or temperatures slow work.
3. Is the estimated hole count a strict drilling plan?
No. It is a planning estimate based on spacing and pattern. Field obstacles, reinforcement, or cracks may shift holes. Use the result to budget time, then adjust layout on site.
4. Should I enter foam cost per cubic foot or cubic meter?
For imperial units, foam is often priced per cubic foot. For metric units, enter cost per cubic meter. If your contractor quotes differently, convert the unit price before entering it.
5. Does the estimator include labor, equipment, and patching costs?
The cost output is material-only. Drilling, pumping labor, mobilization, cleanup, and patching drill holes vary widely. Add those as separate line items for a complete job budget.
6. What if the calculated volume seems unusually high?
Recheck length, width, and lift inputs first. Then reassess void percent; large hidden voids can dominate volume. Consider fixing drainage and edge washout before lifting to avoid repeated settlement.