Can cracks in cinder block be repaired?

Cracks in cinder block walls are a common issue that many homeowners face. While they may seem like a cosmetic problem, left unattended, cracks in cinder blocks can lead to much larger structural issues. Thankfully, there are several methods for repairing cracks in cinder blocks, depending on the width and depth of the cracks.

What causes cracks in cinder blocks?

Cracks in cinder blocks can occur due to a variety of factors, including:

• Settling or shifting of the foundation – If the ground underneath the foundation settles or shifts, it can cause stress and cracks in the cinder block walls.
• Temperature changes – Expanding and contracting due to changes in temperature can cause cracks over time.
• Poor construction – Cinder blocks that are not installed properly or have weak mortar joints are prone to cracking.
• Moisture issues – Water intrusion, either from the outside or inside the structure, can cause cracking as water freezes and thaws.
• Physical impacts – Hitting the wall with objects like furniture or equipment can crack cinder blocks.

Should you repair cracks in cinder blocks?

While some very minor cracks may be cosmetic in nature, it is advisable to repair most cracks in cinder block walls. Here are some reasons why cracks should be repaired:

• Prevent further damage – Cracks that are left unrepaired can worsen over time and lead to larger failures in the wall.
• Maintain structural integrity – Cracks compromise the strength of the wall. Repairing them helps regain structural stability.
• Moisture intrusion – Cracks provide an entry point for water. Repairing them protects against water damage.
• Pest infestation – Cracks allow easy access for pests to enter the wall. Repairing cracks closes off pest entry points.
• Improve appearance – Repairing cracks improves the cosmetic appearance of the wall.

How to repair small cracks in cinder blocks

For small cracks less than 1/8 inch wide, a simple mortar repair is often sufficient. Here are the steps for repairing small cinder block cracks:

1. Clean out the crack – Use a wire brush or chisel to remove any loose debris or mortar from the crack.
2. Dampen the crack – Use water to lightly dampen the inside of the crack before applying new mortar. This helps the mortar adhere.
3. Fill the crack with mortar – Use a pointing trowel to fill the crack with fresh mortar. Pack it tightly into the crack.
4. Smooth the mortar – Tool the mortar with a rounded pointing tool to create a smooth finish. Remove any excess.
5. Keep the mortar moist – Mist the repaired area lightly with water to cure the mortar slowly.

Be sure to match the new mortar mix to the original mortar color. This helps maintain a uniform appearance.

How to repair medium cracks in cinder blocks

For cracks between 1/8 inch and 1/2 inch, a mortar repair is still possible, but may require supports:

1. Clean and dampen the crack as described above
2. Glue concrete wall ties or metal lath strips along the length of the crack with masonry adhesive or mortar
3. This provides support when filling the crack with mortar
4. Fill the crack fully with mortar and tool smooth
5. Mist the area with water to cure

The wall ties act like rebar, reinforcing the repair and preventing further cracking. For very wide cracks, foam backer rod can be inserted into the crack before applying mortar.

How to repair large cracks wider than 1/2 inch

For more substantial cracks wider than 1/2 inch, a mortar repair may not be sufficient. Other repair options include:

• Epoxy injection – Epoxy resin is injected through ports along the crack to fully fill and bind it.
• Rebuilding the wall – Portions of the wall with large cracks may need to be dismantled and rebuilt.
• Steel plate or rebar – Anchor a steel plate or rebar along the length of the crack for support.
• Concrete patch – Cut out the cracked section and patch with fresh concrete.

These repairs may require the services of a professional mason for best results. Always try to determine and address the cause of large cracks during the repair process.

Tips for preventing cracks in cinder blocks

While it’s often impossible to prevent cinder block cracks entirely, here are some tips that can help minimize cracks:

• Construct on solid, well-drained soil or an appropriately designed foundation system like helical piers.
• Use expansion joints at regular intervals to allow for movement.
• Install lintels properly above windows and doors.
• Keep drainage directed away from the cinder block wall to prevent moisture issues.
• Backfill against the wall gradually as the wall is built.
• Use control joints to isolate sections and control cracking.
• Keep the block wall protected from impacts.

Proper design, construction, drainage and protection are key to minimizing cracks. But even with the best methods, some cracks may still occur.

Signs that professional repair is needed

In some cases, severe cracking or other factors indicate a need for professional repair:

• Cracks wider than 1 inch
• Vertical cracks at door or window ends of walls
• Stair-step cracks along the blocks
• Cracks along the control joints
• Horizontal cracks at lintel locations
• Leaks, water intrusion or damage around cracks
• Cracks accompanied by bowing or bulging
• New cracks that continue to expand
• Cracks coupled with sticking doors and windows

If you observe any of these conditions, it is best to consult with a professional mason or structural engineer. They can determine if foundation issues, significant structural damage or design flaws exist.

Cost to repair cinder block cracks

The cost to repair cinder block cracks depends on the size of the cracks, the chosen repair method and who does the work:

Crack Size	Repair Method	DIY Cost	Professional Cost
Hairline to 1/8 inch	Mortar fill	$10 – $30	$150 – $300
1/8 inch to 1/2 inch	Mortar with wall ties	$30 – $60	$300 – $700
Over 1/2 inch	Epoxy, rebar, rebuild	Not recommended	$700 – $1,500+

As you can see, the cost rises significantly for larger cracks that require more extensive repairs. Hiring a professional is recommended for best results on medium and large cracks.

Conclusion

Repairing cracks in cinder block walls is recommended in most situations to maintain structural integrity and prevent further damage. Small hairline cracks can often be repaired with simple mortar filling. Medium cracks may require additional reinforcement with wall ties. Large cracks wider than 1/2 inch typically call for epoxy injection, steel plates or rebuilding the damaged sections. Following proper design, construction and drainage practices can help minimize cracking. But even with robust walls, some cracks may still occur over time. Addressing them promptly with the appropriate repair technique will extend the life of the cinder block wall.