Last Updated on October 20, 2026 by Umar Farooq
Pavers sinking next to concrete slab edges have usually dropped in the strip right beside it, not across the whole patio. That strip is the hardest part of the base to compact, it sits on soil that was disturbed when the slab went in, and it is where water and bedding sand can slip down the gap at the seam. Before you lift anything, find out who moved: lay a straightedge on the slab and run it out over the pavers. If there is a gap under it at the pavers, the pavers dropped. If the slab itself has tilted or cracked, the slab moved, and that is a different job.
Concrete does not care what you think about it. It is rigid, it stays where it was poured, and the pavers beside it are the ones with a reputation for flexing.
Who moved: the slab or the pavers?
My opinion, and the one worth defending: check whether the slab moved before you touch the pavers. Pavers can be lifted, fixed and put back. A slab cannot, so a dip you blame on the pavers but that began in the slab will return.
- Straightedge across the seam. Rest it on the slab, far enough back to be on sound concrete, and let it run over the pavers. A gap under it at the pavers means they dropped.
- Check the slab against a fixed line. A door sill, a garage-door track or a taut string stretched along the slab gives you a reference. A slab that has tilted away from it, or that has a crack with one side lower than the other, has moved.
- Look at the seam itself. A widening gap, or sand and soil disappearing into it, means material is escaping down the edge.
This is my reading aid, not a published test. Rochester Concrete Products' repair guide says a DIY repair is reasonable only when the area is well away from foundations, retaining walls, mature tree roots and other structures, and that movement near foundations, retaining walls or steps is a reason to call a professional (Rochester Concrete Products). That is the right instinct if the slab is the one moving.
Pavers sinking next to concrete slab edges: four causes
Compaction stops short of the slab. ICPI says special attention should be given to compaction next to edge restraints, catch basins and utility structures (ICPI Tech Spec 2). An Interlock Design Association article puts it more bluntly: "the places compaction equipment cannot reach will be at risk of settlement" (IDA). A plate compactor cannot get tight into the corner at a slab face.
Sand and water escape down the seam. ICPI says the perimeter of the base should be inspected for places that let bedding sand migrate, such as joints in curbs and around utility structures, and covered with geotextile to prevent the loss. The same IDA article describes geotextile "turned up at joints against structures." Where a slab edge leaves a gap, sand can work down it a little each rain.
The pavers were laid flush. ICPI allows pavers to sit 1/8 to 1/4 inch above final elevation before compaction, to allow for a small amount of settling. Lay them dead flush with the slab and they finish slightly below it. Our guide to a concrete patio extension with pavers explains why a hair high is the right way round.
The soil beside the slab was disturbed. Digging right up to a slab loosens the soil beside it. That is my inference, not a figure from a source. The site's pavers around house foundation guide makes the same point for foundation backfill, which is rarely compacted well and keeps settling for years.
Water pushing in from above is a fifth suspect. Check where the downspouts and the slope send runoff before you rebuild.
Rebuild the strip, not the whole patio
- Lift two rows back from the slab, stack them in order and strip the sand. Our guide to how to fix sunken pavers covers lifting without breaking pavers.
- Dig down to firm material, but not under the slab. The ground beneath it is holding it up.
- Rebuild the base in thin lifts, damp, finishing with a hand tamper right against the slab so the stone is as dense there as in the middle.
- Consider fabric turned up against the slab face, as the IDA describes, so bedding sand cannot leak into the seam.
- Screed 1 inch of loose sand, relay the pavers 1/8 to 1/4 inch proud, compact, and refill the joints.
Source conflict: ICPI's default is compacted aggregate. The IDA article, written about pool decks, recommends a 4-inch concrete pad as the base in places a compactor cannot reach, with a compacted free-draining layer under it. For a short residential seam I would stay with stone and a hand tamper, and keep the pad as something to ask a contractor about if the strip keeps failing.
Door thresholds, steps and garage aprons
A dip at a door is a trip and water problem as well as an eyesore. ICPI's limit is 1/8 inch of lippage between neighboring pavers on a pedestrian route. The model building code says the landing at a required egress door should be no more than 1 1/2 inches below the threshold (IRC R311.3.1), and that hard surfaces within 10 feet of a foundation slope at least 2 percent away (R401.3). Codes are adopted locally, so check yours. If water now runs toward the slab, fix the slope as part of the repair. See paver driveway apron for the same seam at a driveway.
Fixes that do not hold
- Sweeping sand into the gap. It fills joints, not the void or the loose strip.
- Mortaring the seam. Our foundation page says not to mortar pavers to the wall, and a mortared seam only hides where the dip will reopen.
- Lifting the slab with a quick fix. Slab lifting is a separate trade. I found no neutral source with a method or cost, only contractor listings, so I am not giving numbers.
When the slab or the water is the real problem
Stop and call a professional if the slab is cracked or tilted, the dip is beside a foundation, water drains toward the house, the foundation wall is damp, or you have already relaid the strip once. Photograph the seam with a straightedge and tape, and write the dates down so you can show what changed. Call 811 before digging near the house.
Prove who moved, then rebuild the strip
Pavers sinking next to a concrete slab are usually a base problem in a narrow strip, and a straightedge tells you whether it is that or the slab. Rebuild only the strip, hand-tamp it tight, keep sand out of the seam, and leave the pavers a hair proud so they finish level. After that, the seam should stop being the first place you look.
FAQ
Why are my pavers sinking next to my concrete patio?
Most often the strip beside the slab was not compacted as well as the middle, sand or water is escaping down the seam, or the pavers were laid flush instead of slightly high. Sometimes the slab has moved instead.
How do I tell if the slab or the pavers sank?
Rest a straightedge on the slab and let it run over the pavers. A gap at the pavers means they dropped. Compare the slab against a fixed reference such as a door sill to see whether it has tilted.
Can I fix a dip between pavers and concrete myself?
If the slab is sound and the dip is local, yes. Lift two rows, rebuild the base in thin lifts with a hand tamper against the slab, and relay slightly high. If the slab has moved or the dip is near a foundation, call a professional.
Should pavers be flush with the concrete slab?
Flush after compaction, yes. Set them 1/8 to 1/4 inch high so they settle level, as ICPI allows.
Is a lip between pavers and a step a trip hazard?
It can be. ICPI limits lippage to 1/8 inch between pavers on a pedestrian route, and the model code limits how far a landing can sit below a required door threshold.
