Why Do Paving Slabs Crack And How To Repair Them
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Seeing cracks appear on your patio or driveway can be disheartening after investing time and money into installing beautiful paving. Unfortunately, cracks happen for reasons often beyond your control. But don't worry - cracked paving slabs don’t necessarily mean you need to start from scratch. Depending on the severity, there are affordable ways to fix cracked paving and restore your space.
What Causes Paving Slabs To Crack In The First Place
Ground Settlement
The most common cause of cracks is ground settlement underneath the patio. If the sub-base under your paving was not compacted properly for your soil type, the ground will likely settle unevenly over time. This soil movement places stress on the paving structure, eventually causing visible cracks or raised edges as slabs tilt out of place. Clay and other expansive soils are most vulnerable to shifting and subsidence issues as moisture levels fluctuate dramatically between rains and droughts. But concrete or gravel bases can also settle and transfer cracks to the surface. A thicker sub-base minimises sinking risks over decades of use.Soil Shrinkage & Heave
Similarly, soils like heavy clay alternate between shrinking and expanding as they dry out or become saturated after storms. Cycles of extreme drought then heavy rain can make the ground underneath a patio rise and drop, lifting or settling paving slabs above. This inevitably strains slab joints until cracking damage appears - usually during summer or after winter freezes.Poor Installation Techniques
Laying paving without full mortar support also frequently causes later cracking. Dot-and-dab installs with just mortar dots or corners leave hollow areas for water to pool and freeze, weakening pavers over time. Fully bedding slabs across a concrete or 4:1 mortar base prevents these issues.How To Repair Cracked Paving
If your patio has cracks, all is not lost! Here are four practical solutions to restore your surface:1. Slab Resurfacing
Resurfacing covers cracks with fresh paving laid over the damaged layer beneath. But hairline cracks often continue growing until they mar the new surface too. Resurfacing alone rarely resolves uneven sinking or soil issues under the original slabs.2. Mudjacking
Mudjacking lifts sunken slabs by injecting mortar mixture to fill voids via holes drilled through the paving surface. It works well for concrete repairs but poses challenges on softer natural stones that can crack under pressure. And later soil settling can sink heavy mortar just like original slabs.3. Polymer Packing
For a lighter support approach, polymer packing pumps expanding polyurethane foam under slabs instead of concrete mortar. The foam lifts gently and leaves durable support that won’t contribute weight to re-sink patios. Polyurethane offers an excellent modern solution for raising concrete pads and preventing additional cracks long-term.4. Spot Slab Replacement
Replacing just a few damaged slabs keeps costs affordable. Simply lift the compromised pavers, rebuild the base layer properly with packed gravel and fresh concrete, then relay replacement slabs seamlessly anchored to stable surroundings.Prevention Is The Best Solution
No patio lasts indefinitely. But quality materials made for local conditions, installed properly atop a well-graded base of adequate thickness, will make paving withstand decades rather than just years of family use before cracks appear. Pay careful attention to drainage and moisture levels around the perimeter too - allowing the underlying soil to alternate between bone dry and saturated greatly accelerates shifting and damage. With a quality foundation and mindful care, beautiful paving can last 50 years or more before major overhaul. Don't let a few cracks spell complete disaster - timely repairs keep patio problems minor."As a professional landscaper, proper base preparation is absolutely crucial. Compacting gravel and precision grading prevent 90% of paving slab cracks down the road. If issues do arise later on, targeted mudjacking or replacing single slabs saves big money compared to fully reinstalling an entire patio." - Steven Bell, Paving Shopper Landscapesz