5 Reasons Your Patio Is Sinking and How to Fix Them
What do you do when your patio sinks faster than your weekend plans?
Improperly prepared soil is a top culprit for patio sinking.
Poor drainage can wash away base materials, causing tilting.
Decaying tree roots and heavy loads can impact a patio’s stability.
Patios in areas with cold winters are at risk due to freezing and thawing.
Fixing many patio problems ranges from $730 to $2,500.
For many homeowners, their outdoor space is their happy place. So, of course, panic ensues when your patio starts to sink. From shifting soil to drainage disasters, understanding why the patio is sinking is the first step toward fixing your oasis. Here are the five most common reasons your patio is going under and how to bring it back up.
1. Poor Soil Compaction
Poorly compacted soil beneath the surface is one of the most common culprits behind a sinking concrete patio. The ground beneath must be adequately compacted during installation to create a stable base. If this step is rushed or skipped, the soil can settle over time, dragging your patio down.
Depending on the extent of the issue, repairing your patio may cost $730 to $2,500. Working with a local deck repair specialist will help you find an ideal solution for your budget.
The Solution
Mudjacking is a cost-effective way to lift and level a concrete patio by pumping a slurry mixture under the slab.
Polyurethane foam injection is a modern mudjacking alternative that uses high-density foam to lift the slab.
Rebuilding the base may be necessary for severe sinking.
2. Drainage Problems
Water collecting around or beneath your patio can erode the soil supporting it. Poor drainage slowly washes away the base, leaving your patio to sink or tilt toward the area with the worst erosion. To avoid these issues, it is essential to understand who installs concrete patios to ensure proper drainage.
The Solution
Install a French or channel drain to divert water from the patio, protecting the base layer.
Grade the surrounding landscape to slope the yard away from the patio to prevent water pooling.
Consider replacing solid concrete slabs with patio pavers to boost water absorption and reduce erosion.
3. Decaying Tree Roots
Tree roots beneath a patio can push up pavers or crack concrete slabs. But when those roots die and decompose, they leave behind voids that may eventually collapse, causing patio sections to sink.
In this instance, you may need to rebuild. Homeowners can expect the cost to build a patio to be around $4,000, but your final bill can vary quite a bit. Simple designs might run as low as $800, while larger patios with custom features or upscale materials can push the price north of $14,000. But first, any pro you hire will address the decay.
The Solution
Remove old roots by excavating the affected area and removing dead or rotting roots.
Fill the void with compacted soil or gravel to restore stability.
Install a root barrier to redirect future root growth.
4. Heavy Loads
Over time, you may have added a hot tub, outdoor kitchen, or other hefty features to your patio. All of the extra weight could be too much for your existing base. Without reinforcement, a patio may slowly sink under the pressure.
The Solution
Reinforce the base if your concrete patio is in good shape by pouring an extra layer of concrete.
Add support footings by cutting out patio sections and digging beneath the slab to install concrete piers.
Consult a structural engineer for severe sinking to address the situation and avoid issues later.
5. Freezing and Thawing
When moisture in the soil freezes, it expands, pushing your patio upward. Once the ice melts, the ground settles again, but not always evenly. Over time, this freeze-thaw cycle can leave your patio looking sunken, sloped, or uneven.
The Solution
Improve drainage to steer water away from the patio to reduce freeze-thaw damage.
Use frost-proof materials like concrete pavers, which can often withstand cold-weather expansion better than a large concrete slab.
Consider deeper footings to ensure the patio base extends further below the frost line in your local area to prevent shifting.
Signs That Your Patio Is Sinking
Are your patio problems just cosmetic or something more serious? Here are the most common signs that your patio is sinking:
Uneven or sloping surfaces
Pooled water after rain
Cracks in slabs or pavers
Wobbly furniture due to an uneven surface
Trip hazards where pavers no longer align
When to Call a Pro
Unless you are an experienced DIYer with a background in patio building, it is best to call in a pro for sinking issues. Professionals can pinpoint the root cause and recommend the most effective fix, helping you avoid costly DIY mistakes.
While DIY repairs might save money up front, an expert knows how to ensure your patio stays safe, level, and long-lasting. That's the best way to protect your investment in your outdoor space.
Pros often use mudjacking or polyurethane foam injection to level a sunken concrete patio. Both methods lift the slab by filling voids beneath it. After properly compacting the soil beneath it to prevent future settling, the concrete may need to be removed and re-poured for severe sinking.
It depends on your priorities. Concrete is more affordable and faster to install, but pavers offer better drainage, are easier to repair, and can create a more high-end look. If budget and speed matter most, go with concrete. If you want style and flexibility, pavers are the better bet.
A properly installed 6-inch concrete slab, mixed and cured under the right conditions, can support about 3,000 pounds concentrated over a single square foot without buckling. Conversely, concrete pavers can handle around 8,000 pounds per square inch when laid over a solid, well-compacted base.
