How to Fix a Broken Patio – Complete Guide

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8 min read|Updated: Jun 27, 2026|By Home Repair Expert

Quick Answer

A broken patio is repaired based on material: concrete cracks fill with polyurethane or polymer-modified concrete crack filler, sunken pavers lift, re-level the sand base, and reset. Loose stone or concrete slabs lift, scrape old mortar, apply fresh exterior tile mortar, and re-set level with a rubber mallet. Clean the joints and let cure 24 hours before walking on.

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A broken patio, with cracked slabs, sunken areas, wobbly stones, or weeds pushing through the joints, spoils the look of your garden and can become a real trip hazard. The good news is that most patio problems can be repaired yourself with some basic materials, restoring a safe, level, and attractive surface.

This guide covers how to fix the most common patio issues, from cracked and loose slabs to sunken sections and crumbling joints, with durable results that last through the seasons.

Why Patios Crack and Sink

Patios face weather, ground movement, and weight, so damage develops over time. The usual causes are:

• Poor or settled base: A sub-base that was not properly compacted, or that has settled, lets slabs sink and rock.
• Freeze-thaw damage: Water in cracks and joints freezes, expands, and breaks up slabs and pointing.
• Failed jointing: The mortar or sand between slabs washes out, leaving gaps where weeds grow and slabs shift.
• Tree roots and ground movement: Roots and shifting soil lift and crack the surface.

Tools and Materials You Will Need

• Replacement slabs (matching)
• Sand and cement or ready-mixed mortar
• Patio jointing compound
• Rubber mallet
• Bolster chisel and club hammer
• Spirit level
• Trowel
• Stiff brush
• Work gloves

Step-by-Step: How to Repair a Patio

Step 1: Lift the Damaged Slab

Carefully chip out the old jointing around the broken or sunken slab with a bolster chisel, then lever it up and remove it without damaging the surrounding slabs.

Step 2: Prepare and Level the Base

Clear out the old bedding and check the sub-base. Add or compact fresh sharp sand or a sand-and-cement mix to create a firm, level bed at the correct height.

Step 3: Bed the New Slab

Lay the replacement slab onto the fresh mortar bed and tap it down gently with a rubber mallet. Use a spirit level to make sure it sits flush and level with the neighboring slabs, with a slight fall for drainage.

Step 4: Re-point the Joints

Once the bedding has set, fill the joints around the slab with a patio jointing compound or a dry sand-and-cement mix, pressing it firmly in and brushing off the excess for a neat finish.

Step 5: Tackle Weeds and Crumbling Joints Elsewhere

While you are at it, brush out weeds and loose pointing across the patio and refill those joints too, which prevents further slabs working loose.

Pro Tips to Prevent This Problem

• Always lay slabs with a slight fall away from the house so water drains off rather than pooling.
• Use a proper jointing compound to keep weeds out and stop slabs shifting.
• Fix loose or cracked slabs promptly before they become a trip hazard or let water undermine the base.

When to Call a Professional

Call a professional if large areas of the patio have sunk or heaved, which points to a failed sub-base needing relaying, or if drainage problems keep causing damage. Extensive relaying is heavy, skilled work that a landscaper can do far more efficiently.

Frequently Asked Questions

How do I fix a sunken patio slab?

Lift the slab, add and compact fresh bedding to bring it back to the right level, then re-lay it on a fresh mortar bed and re-point the joints. Check it sits flush with a spirit level.

What should I use to fill patio joints?

A dedicated patio jointing compound or a dry sand-and-cement mix works well. Proper jointing keeps weeds out and stops the slabs shifting underfoot.

Why do weeds keep growing in my patio?

Weeds take hold where the jointing has washed out. Brushing out the old material and refilling the joints with a proper compound keeps them from coming back.

Final Thoughts

A broken patio is usually very fixable with a weekend of work. Lift and re-bed cracked or sunken slabs on a firm, level base, re-point the joints, and clear out weeds across the surface. Lay everything with a slight fall for drainage, and your patio will be safe, level, and looking smart again, ready to enjoy for years.