Repairing Cracks on Concrete Walls

Concrete Wall crack repair is a simple procedure that can usually be completed within a day or so. Cracks on concrete walls, particularly a basement wall due to settlement, frost heave, or ground movement can be either structural or non-structural. Having cracks appear on your wall may be a cosmetic problem, or it could indicate a more severe and structural issue. The first step to fixing the problem is identifying which one it is:

A good indicator of structural cracks on concrete walls is looking at how long and large the wall crack is. If it is substantial (more than 1.5 inches wide), and the crack persists even after numerous repair jobs, or you have difficulty closing your windows and doors, it might signal a structural problem. At this stage, it is best to rope in a professional to assess the situation and handle the job for you.

Non-structural cracks—hairline cracks on concrete walls; however, are more common in most homes and are sometimes unavoidable. They tend to surface near windows and doors and can appear due to a variety of reasons.

Identifying the cause and learning how to repair cracks on concrete walls properly can help you avoid similar situations in the future.

Repair Cracks on Concrete Walls at Home

To repair a concrete wall, you will need an epoxy repair kit. The epoxy will make a watertight seal in the crack. Begin your repair by tapping 3-inch finish nails partially into the crack every 12 inches; these nails will attach injection ports. Epoxy comes in two parts, A and B, which you need to mix just before using. Mix equal parts of the epoxy on a scrap piece of wood with a putty knife. Apply a small amount of mixed epoxy on each injection port tab; attach each port against the wall by covering each of the finish nails with one port. Spread mixed epoxy over the crack, extending 1 inch on either side of the crack. Cover the flange of each injection port with epoxy as well. You can use a paintbrush dipped in mineral spirits to feather the epoxy at the edges. Allow curing for six to 10 hours. Using a caulk gun, inject liquid concrete repair into the ports, starting at the bottom, until the liquid oozes from the port. Plug each port before moving to the next. Allow to cure for at least five days, then cut the port flush with the wall with a hacksaw.

If cracks on concrete drywall or plaster are deeper than a 1/4 inch, you will have better success if you first fill the crevice with a filler compound before taping with joint compound. Mix the compound as per the manufacturer’s instructions. Fill the crack until it is flush with the existing wall. Cover with tape and joint compound, as outlined previously, to achieve a smooth wall.

How to Repair Wide Cracks on Concrete Walls

The secret to repairing wide concrete cracks is to undercut the sides of the crack to give it an inverted “V” shape. This helps the repair material to “key” into the crack, creating a mechanical bond in addition to the chemical bond between the patch material and the concrete.

• Chisel the crack with a hammer and masonry chisel to widen the base of the crack and to dislodge any loose material from the old concrete.
• Remove all debris from the crack, using a wire brush. If desired, clean the crack with a pressure washer or a garden hose and spray nozzle.
• Remove all water and debris from the crack with a wet/dry shop vacuum or a brush. Work carefully to remove all dust and grit from the crack. It’s OK if the surfaces are wet, but there should be no pools of water.
• Mix the concrete patching compound, following the manufacturer’s directions.
• Trowel the compound into the crack. Stab the trowel into the compound to remove air pockets and help work the patching material deep into the crack. Fill the crack up to the surrounding concrete surface.
• Smooth the surface of the patch with the trowel, feathering the compound into the surrounding concrete.
• Brush the surface of the patching compound with a dry paintbrush to texture the surface, if desired.
• Let the compound cure as directed.
• Paint or seal the surface of the patch and surrounding area, if desired.

How to Repair Narrow Concrete Cracks

Narrow concrete cracks can be filled using masonry crack elastomeric filler that can be applied with a caulking gun. Alternatively, many products come in bottles with an applicator tip. Tiny cracks, such as hairline cracks, can be repaired using a vinyl concrete patching compound applied over the crack and then smoothed with a putty knife or trowel. For hairline cracks, applying repair caulk or crack filler over the cracks usually is not effective, as the caulk tends to peel off of the surface over time.

Narrow cracks can be deep, often extending through the entire thickness of the concrete slab. Therefore, it’s a good idea to start the repair by stuffing foam backer rod into the crack to create a base to hold the repair material. Backer rod is solid in a variety of sizes; use a rod diameter that is slightly larger than the width of the crack. Stuff the backer rod into the crack with a screwdriver to a depth of 1/4 inch. Fill the crack with the repair material, following the manufacturer’s directions.

Virtue Construction provides logistics services for construction materials. Contact Us for more.

Modern additives modify precisely that timespan; however, the amount of additive added to the mix is very important. Virtue Industries manufactures ready-mix concrete under high-end expert supervision to ensure high-quality end products.