Key points
- A sunken surface may reflect base, edge, water, frost, soil, or loading conditions.
- Price the area needed to reach stable support, not only the visible depression.
- Keep finished grades, replacement units, outlet, and warranty assumptions in writing.
- Resetting pavers is not a substitute for correcting active movement.
Describe the movement before lifting pavers
“Sunken” describes the visible result, not the cause. A low area may reflect inadequate base preparation, washed material, a blocked or leaking drain, buried organic matter, soft soil, frost-related movement, a failed edge, or concentrated loading. Several conditions can overlap.
| Pattern | What the contractor should investigate |
|---|---|
| One or two low units | Local bedding, damaged pavers, or a small base defect. |
| Broad depression | Settlement, wet subgrade, fill, or a wider grade problem. |
| A low line beside an edge or wall | Loss of edge support, drainage trouble, or undermining. |
| A dip that appears after rain | Runoff, infiltration, a pipe leak, or soil migration. |
| Repeated seasonal movement | Moisture, frost, roots, loading, or a deeper unstable layer. |
Observe the patio during or after rain when water paths are visible. CMHA maintenance guidance describes some low-severity paver distress that can be addressed by lifting and reinstating units, while other conditions require correcting the base, bedding drainage, edge restraint, or frost-related issues. This guidance helps frame questions; it does not diagnose a particular patio.
Price the repair boundary honestly
A localized reset may involve lifting and relaying a defined area. A base reconstruction can add removal, excavation, disposal, replacement aggregate, compaction, edge repair, drainage, and restoration. Narrow access or hand handling can matter more than the number of pavers. If a utility, downspout, step, or retaining wall lies nearby, the repair boundary may extend beyond the visible depression.
Ask whether the contractor will lift only the low units or dismantle back to stable support. The estimate should identify storage and reuse of pavers, inspection of bedding and base, replacement material, joint restoration, and finished grade. Request a written allowance for unsuitable soil, groundwater, buried debris, or a failed outlet if the depth is unknown.
Correct the cause and the transition
If water contributed to settlement, identify its source and receiving point before closing the excavation. If an edge failed, include restraint and adjacent soil. Check the finished elevation against doors, steps, drains, lawn, and foundation so a repair does not create a new low point or send runoff to a structure.
Ask the contractor to mark the work limit and state what observation would require lifting more units or rebuilding a larger area. A surface reset may fit when the cause is understood and the adjacent support is stable. Broad movement, recurring washout, or uncertain groundwater may need a different assessment.
Plan for future service
Keep spare pavers, layout and product details, photographs of the exposed base, final grades, and drainage or utility locations. Ask whether a warranty covers material, installation, or recurrence and what maintenance is expected. A future utility or drainage opening can then be restored with better color matching and less repeated investigation.
Cold-weather movement is one possible contributor, not a catch-all explanation. Soil, water, compaction, loading, and the installed system also matter. A permeable pavement assembly differs from conventional pavers and should be priced and maintained separately. U.S. new-installation price signals do not establish repair prices or a Canadian budget.
Agree how far the repair reaches
The repair boundary should be shown on the patio before units are lifted. Ask whether the work ends at a visually straight line, an existing edge, or the point where the base and surrounding grade appear stable. A tidy boundary can reduce the number of units handled but may leave a moving or unsupported transition just beyond it. The estimate should say how the contractor will assess adjacent pavers and who approves an expanded area.
Confirm how lifted units will be stored, cleaned, and protected, whether broken units are replaced, and how color or batch differences will be handled. Ask how the edge is restrained again and how joint material is restored. If the repair crosses a drain or service route, identify who verifies that the line works before the patio is closed. These details make a localized reset comparable with a more extensive base repair and clarify what the price does not promise.