This calculator estimates the pedestal stem height needed at each grid point to keep pavers level over a sloped base.
- Measure your base slopes in percent along X and Y.
- Set a reference stem height at the first corner.
- Enter grid spacing based on paver size or layout.
- Check the min and max heights for your pedestal range.
- Download the table for marking and installation.
Sample layout using millimeters and a single-direction slope.
| Rows | Cols | Spacing | Slope X | Reference stem | Max stem |
|---|---|---|---|---|---|
| 3 | 3 | 600 mm | 1.5% | 25 mm | 43 mm |
| With 1.5% grade, each 600 mm step increases by 9 mm. Two steps from Col 1 to Col 3 adds 18 mm. | |||||
Site measurements that drive accurate heights
Start by mapping the area into a simple X–Y grid that matches your paver layout. Measure slope in both directions with a laser level, water level, or digital inclinometer. Record the percent grade and confirm the high point and low point corners. Note membrane thicknesses and any protection layers that change the base elevation. Small measurement errors compound across long runs.
How pedestal stems compensate for base slope
The calculator keeps the finished surface level by adjusting each pedestal stem. For every grid step, the vertical change equals run × slope(%)/100. As you move along X and Y, the stem height increases or decreases by the summed vertical changes. Enter all runs in one unit system, because mixed units distort results. If your “uphill” corner is opposite, flip the slope direction option to match field reality.
Choosing spacing for stability and drainage
Spacing should follow paver size, expected loads, and manufacturer limits. Tighter spacing improves stiffness and reduces rocking, while wider spacing reduces pedestal count. Add extra support near corners, edges, and around planters where load paths concentrate. If drainage mats or protection boards are used, keep spacing uniform so deflection stays predictable and water paths remain clear.
Range checks and adjustment strategy
Pedestals have minimum and maximum adjustment limits. If some points fall outside range, increase the reference stem at the chosen corner, reduce spacing, or split the deck into zones with different reference heights. Consider using shims or fixed bases only where permitted. Range checks help prevent field improvisation and keep crew installation efficient.
Using exports for installation control
Download the CSV for quick sorting by row or column, then mark pedestal locations with chalk lines or layout strings. Use the PDF as a jobsite handout with summary values and the full table. The “total stack” column adds paver thickness and top pads, which helps verify clearances at doorsills and drains. After setting stems, recheck corners and a midline with a straightedge to confirm level.
1) What does “stem height” mean here?
It is the adjustable pedestal body setting needed at each grid point. It excludes paver thickness and top pads, so you can match the pedestal model’s adjustment range accurately.
2) Why are there two slope inputs?
Many bases fall in two directions. Enter the percent grade along X and Y to capture diagonal changes, then the calculator sums both effects for each pedestal location.
3) How do I measure slope in percent?
Measure a horizontal run and the vertical rise or fall. Percent slope equals (rise ÷ run) × 100. Tools like digital levels often display percent directly.
4) What if some points are out of range?
Increase the reference stem height, reduce spacing, or divide the surface into zones with different reference corners. This keeps each pedestal within its safe adjustment limits.
5) Should I use total stack or stem height on site?
Set the pedestal using stem height. Use total stack to confirm clearance to thresholds, drains, and rails because it adds paver thickness and pad allowances.
6) Does this replace manufacturer guidance?
No. It is a planning tool to organize heights and exports. Always verify pedestal spacing, load ratings, and allowable shimming methods in your product documentation.
- Use a laser level or string line to confirm field elevations.
- Allow extra clearance for drainage mats, membranes, or protection boards.
- For large slopes, split the area into zones with different reference heights.