Sunny backyard patio with plants and residential buildings.

How to Fix Cracks in Concrete Patio: A Step-by-Step Guide

Maintaining a concrete patio involves regular inspection and prompt repair of any damage it may endure over time. Cracks in the concrete are not only unsightly, but they can also lead to further deterioration if left unaddressed. Fortunately, repairing cracks in a concrete patio is a manageable DIY project that can restore the look and longevity of your outdoor space.

Green plants on cracked gray concrete surface.

The causes of cracking can range from natural shrinkage and thermal expansion to stress and excessive load. Recognizing the type of crack is crucial as it determines the appropriate repair method. Hairline cracks might only require a simple sealing solution, whereas larger, more substantial cracks may demand a more robust approach such as a concrete repair mix.

To ensure a successful repair, one must start with a clean surface, removing any loose material. Filling the cracks with a suitable sealant or a concrete repair product can help prevent water infiltration and future damage. For more extensive repairs, resurfacing the entire patio might be the most effective way to achieve a uniform appearance and structural integrity. By tackling this project, homeowners can extend the life of their concrete patio and enjoy a functional outdoor space for years to come.

Identifying Types of Cracks

Hands on cracked dry earth pattern.

When addressing cracks in a concrete patio, it’s essential to start by identifying the type of crack, as this determines the appropriate repair method. Cracks can vary in size, depth, and cause, each requiring a specific approach.

Hairline Cracks

Hairline cracks are narrow, surface-level fractures in the concrete, usually less than 1/8 inch wide. They are often a result of minor concrete shrinkage as it cures. While usually not a structural concern, they can allow water and other contaminants to penetrate and worsen if not properly sealed.

Deep Cracks

Deep cracks extend through the concrete slab to its base and are wider than hairline cracks, typically over 1/4 inch in width. These types of cracks might be caused by heavy loads, underlying soil movement, or freeze-thaw cycles. They often necessitate a more robust repair strategy, including the use of a concrete repair mix to ensure stability and prevent further damage.

Cracks at Corners

Cracks at corners are commonly observed where two edges meet, and they may signal a lack of support or structural integrity at those points. The cracking here could be due to uneven settling of the base or excessive weight applied to the corner area. Repairing these cracks usually involves assessing the underlying support and employing strategic reinforcement in addition to filling the crack.

Preparing the Concrete Patio for Repair

Person breaking concrete with pickaxe and shovel.

Before attempting any repair on a concrete patio, it is essential to prepare the surface to ensure that the filler materials adhere properly and the repair is long-lasting. Proper preparation involves cleaning the area, removing any debris, and assessing the damage in detail.

Cleaning the Area

One must ensure that the concrete surface is clean and free of any dirt, dust, or stains before beginning the repair process. Using a pressure washer and concrete cleaner can effectively remove grime and prepare the surface. For best results, follow the cleaner-manufacturer’s application instructions, ensuring the entire area is free of contaminants.

Removing Debris

After cleaning, it is crucial to remove any loose concrete or particles within the cracks themselves, as these can prevent the repair material from bonding correctly. A wire brush can be used to scrub the interior of the cracks, while a putty knife can help dislodge stubborn bits of debris.

  • Tools for debris removal:
    • Wire brush
    • Putty knife
    • Compressed air or a shop vacuum for fine particles

Assessing the Damage

Thorough examination of the cracks is required to determine the extent of the damage. Smaller, hairline cracks may require a simple sealant, while larger, more significant cracks could indicate underlying issues. Measure the width and depth of the cracks to decide on the appropriate repair approach.

  • Damage assessment checklist:
    • Width and depth: Measure the size of the cracks to choose the right filler material.
    • Underlying issues: Check for possible causes of cracking such as tree roots or water damage.

By meticulously cleaning the area, removing debris, and carefully assessing the damage, one creates the optimal conditions for an effective and durable concrete patio repair.

Materials and Tools for Repair

Construction materials: cement, sand, and wheelbarrow.

Before starting the repair process, it is vital to choose a material suitable for the type of damage and to gather all necessary tools to ensure a smooth application.

Choosing the Right Repair Compound

For small cracks, a polymer-based concrete crack filler can be an effective solution. These fillers are ready to use and can quickly seal cracks, preventing further deterioration. Another option for hairline cracks is a caulk-based product, easy to apply and capable of excluding water and pests from the crack. For larger cracks or chipped areas, a concrete patch made from Portland cement and masonry sand provides a sturdy fix. Quikrete Concrete Repair is a popular, pre-mixed patching compound that’s simple to apply and designed for heavy-duty repairs.

Gathering Necessary Tools

To effectively apply a concrete repair compound, certain tools are required:

  • Trowel: For smoothing and leveling the patching material.
  • Chisel: To remove loose pieces of concrete and to shape the crack before applying the filler.
  • Hammer: Assist in chipping away any unstable concrete when prepping the area.
  • Wire Brush: To clean the crack of debris and dust before applying the repair material.
  • Caulk Gun (if using caulk-based product): For precisely applying and sealing cracks.
  • Mixing Paddle (for mixable compounds): Ensures a consistent and homogenous mix of the patching compound.
  • Safety Glasses and Gloves: To protect eyes and hands during the repair process.

Having the right materials and tools on hand before beginning the repair will lead to a more durable and visually pleasing result.

Repairing the Concrete Patio

Worker pouring concrete from wheelbarrow at construction site.

When setting out to repair a concrete patio, it is essential to select appropriate materials and employ the correct techniques for filling cracks, depending on their size. Proper curing and sealing are crucial to ensure the longevity of the repair work.

Filling Small Cracks

For small cracks, one can typically use a polyurethane or epoxy injection. These materials adhere well to the concrete and can prevent further damage. The process involves cleaning the crack with a brush and then filling it with the chosen sealant. For cracks narrower than 1/4 inch, a caulk-style sealant can be used, which provides a flexible and weather-resistant seal.

  • Materials Needed:
    • Sand (to fill in large voids)
    • Polyurethane or epoxy sealant

Repairing Large Cracks

Large cracks require a different approach. If the crack is wider, it’s necessary to use a backer rod, which is a flexible foam that fills the space in the crack before applying the sealant. This prevents the sealant from sinking deep into the crack and wasting material. Once the backer rod is in place, apply a concrete resurfacer – a strong material that can endure the expansion and contraction of the concrete.

  • Process Steps:
    1. Insert backer rod into the crack.
    2. Overlay with concrete resurfacer for a smooth finish.

Curing and Sealing

After applying the repair material, the patio must undergo curing. This period allows the materials to harden and achieve the necessary bonding strength. When curing is complete, it’s advisable to apply a sealant, which acts as a protective layer against moisture and temperature fluctuations, ensuring that the repair lasts longer. Choose a sealant that’s appropriate for outdoor conditions and compatible with the repair materials used.

Curing Notes:

  • Allow sufficient time for materials to harden.
  • Apply the sealant to protect the repaired area.

Finishing Touches and Maintenance

After repairing cracks in a concrete patio, the final steps ensure longevity and aesthetic appeal. These measures prevent future damage and maintain the patio’s refreshed look.


Resurfacing a concrete patio provides a fresh, new surface that can make old concrete look like new. An important consideration in resurfacing is ensuring that the temperature is conducive to the material setting properly; avoid extreme weather conditions such as frost heave or excessive heat. After filling the cracks with a crack filler, they should apply a resurfacing product uniformly across the surface with a concrete broom to give it a non-slip texture.

Painting and Sealing

Once the resurfacing material has cured, painting and sealing can protect the concrete from the elements. Use a paint or sealant suitable for exterior concrete surfaces; it should be capable of expanding and contracting with temperature changes to prevent it from cracking. Sealing the concrete not only protects it from weather conditions but also reduces the chance of it becoming a trip hazard by sealing small imperfections that could catch a shoe.

Preventive Measures

Routine maintenance is crucial to extend the life of a resurfaced and sealed patio. They should sweep regularly to prevent debris from settling in small crevices and keeping drainage areas clear to prevent water buildup. In winter months, use safe ice melt products that do not cause damage to the concrete, and repair any new cracks or issues promptly to prevent them from worsening.

By taking these finishing steps and adopting a thorough maintenance routine, one can ensure their concrete patio remains in good condition, thwarting potential damage from weather and temperature fluctuations.