Patios & Paving · Problem & repair
Uneven patio slabs and trip hazards
An uneven patio is a safety issue before it is an aesthetic one - a lip of more than a few millimetres is enough to catch a toe, and it tends to get worse rather than settle.
The good news is that the repair is contained. Individual slabs can usually be lifted, re-bedded and put straight back.
How to tell this is your problem
- A visible step between adjacent slabs
- Water sitting in a dip after rain
- Slabs rocking when walked on
- Cracked pointing along the same line
- Furniture no longer sitting level
Repair or replace?
Repair. A patio only warrants full replacement when the majority of slabs have moved, the fall is wrong throughout, or the slabs themselves are failing.
Repair options, cheapest first
- 01
Lift and re-bed on a full mortar bed
The slab is lifted, old bedding removed and a full bed laid so the whole underside is supported. This is the standard permanent repair.
- 02
Localised sub-base repair
Where the ground has settled, the excavation goes deeper and compacted Type 1 is re-formed before re-bedding.
- 03
Re-point after re-levelling
Any repair is finished by raking out and re-pointing the surrounding joints so water cannot get back beneath.
- 04
Re-lay the affected zone
Where a whole section has moved, taking up and re-laying that area to a consistent fall is quicker and neater than chasing individual slabs.
Why it happens
Spot-bedded slabs
Slabs laid on five dabs of mortar rather than a full bed have unsupported centres and voids beneath. They rock, then crack.
Ground settlement
Fill, made-up ground or a backfilled trench continues to consolidate for years and takes the paving down with it.
Frost heave
In poorly drained ground, water beneath the bedding expands on freezing and lifts individual slabs.
Root growth
Nearby shrubs and trees push individual slabs upward, usually one or two at a time.
Cost and time on site
Indicative cost
Individual slab re-bedding is a low-cost visit; re-laying a section is priced by area.
Typical duration
A handful of slabs is half a day. A full section is typically one to two days plus curing.
Every quote is priced after seeing the site. Trip hazards are usually a same-day fix - tell us how many slabs have moved.
Uneven patio slabs: common questions
- Why do patio slabs rock?
- Nearly always spot-bedding. The slab bridges voids between the mortar dabs, so it pivots under load and eventually cracks across the middle.
- Can slabs be re-used when lifted?
- Usually yes, if they come up cleanly. Old mortar is cleaned off the underside before re-bedding.
- How much of a step counts as a trip hazard?
- Anything you can catch a shoe on is worth fixing. Small lips grow as water gets underneath the higher slab.
- Should a patio be laid perfectly level?
- No - it needs a slight fall away from the house so surface water runs off rather than sitting against the wall.
Services that fix this
Related reading: Porcelain vs Sandstone: Which Patio Material Wins?
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