How To Patch a Hole in a Brick Wall

The front wall of our house has some bricks that are falling apart. We have replacement bricks on hand but no clue as to how to replace them without damaging the intact ones.

—Robin Dolbow of Shoreview, MN

Whether you’re dealing with crumbling bricks or an old vent opening, knowing how to repair brick walls is a skill that can save you money and protect your home from further damage.

In this article and accompanying video, This Old House mason Mark McCullough shows us how to patch a brick wall and shares the tips and insights he’s picked up from decades in the trade.

*Costs in this article sourced from contractor estimates used by Angi, HomeAdvisor, and HomeGuide.

Understanding the Brick Wall Repair Process

Before starting the repair, figure out the scope of the project and buy or rent the materials you’ll need. Patching a hole in a brick wall involves more than simply filling the gap; it requires careful planning and execution to blend it into the existing brickwork.

Assess the Damage

The first step in repairing a brick wall is to assess the extent of the damage. In the video, McCullough examines a hole in a garage wall that’s about one brick wide and two bricks high.

While it might be tempting to fill the hole with just mortar, maintaining the wall’s running bond pattern (i.e., installing new bricks as part of the repair) is essential for the wall’s overall structural integrity and aesthetic uniformity.

Materials and Tools

While you can always buy the heavier-duty tools, we recommend renting them if they’re for one-time use. To successfully patch a hole in a brick wall, you’ll need:

• Angle grinder with dust shroud
• Bucket
• Flat pointer
• HEPA vacuum
• Hammer
• Mask
• Masonry brush
• Masonry jointer
• Masonry trowel
• Matching bricks
• Mortar mix
• Safety glasses

McCullough emphasizes the importance of finding matching bricks, which you can typically find at a local brickyard. For mortar, a standard gray Type N premixed mortar will generally work for most residential applications.

Preparing the Wall Work Area

Prepping the wall for repair includes removing damaged bricks and cleaning the area thoroughly.

Remove Damaged Bricks

To remove damaged or cut bricks, McCullough recommends using an angle grinder with a dust shroud attached to a HEPA vacuum. This setup helps control the potentially harmful silica dust produced when cutting mortar from getting into the air and settling in your yard.

Here’s how to begin:

1. Cut along the mortar lines closest to the bricks you’re removing.
2. Make cuts that will replicate the wall’s existing brick pattern.
3. Be careful not to nick adjacent bricks you want to preserve.

Once you’ve popped out the bricks, clear any debris and loose mortar from the hole.

When clearing debris from the hole, aim to expose at least three-quarters of an inch of the surrounding brick surface. As McCullough explains on the show, “Mortar does not stick to mortar. So, if we smeared mortar onto that joint, it would just eventually break off. Mortar does stick to brick. And that’s why we like to go in at least three quarters of an inch.” The more clean brick surface you reveal, the stronger your new mortar bond will be.

Clean the Work Area

After removing the damaged bricks, perform the following steps:

1. Use a dry masonry brush to remove loose dust and mortar.
2. Follow up with a wet brush to thoroughly clean the area.
3. Let the area dry before starting the repair.

A thorough cleanout will help the new mortar form a durable bond.

Why It Matters: Mark, a This Old House masonry expert, warns that skipping proper prep leads to failure: “This happens when you don’t properly wet the surrounding brick before applying the mortar. If you skip that step, the moisture gets sucked out of the mortar as it dries and you’re left with what we call dusty mortar.” Make sure to dampen the surrounding brick before applying new mortar to prevent this common problem.

Mixing and Applying Brick Mortar

You can’t expect your repair to last unless you have the right mortar consistency and apply it correctly.

Here’s how to do both.

Get the Right Consistency

McCullough tells us to mix the mortar until it reaches an oatmeal-like consistency. It should be malleable but not too wet—too much water in the mixture will weaken the mortar’s ability to bond. Use a bucket and a proper mortar mixing tool to achieve a uniform texture.

Pro Tip: Mason Lenny Moreira, a veteran with 30 years of experience, lives by the mantra “Wetness leads to weakness.” According to This Old House Magazine, Moreira begins by blending the dry ingredients—Portland cement, sand, and mason’s lime—before adding water slowly and sparingly, with an eye to consistency. He maintains control of the wet/dry fusion by making a volcano shape in the dry mix and pouring only one cup of water at a time into the center.

Apply Mortar and Set Bricks

To apply mortar and set bricks, follow these steps:

1. Spread a bed of mortar along the bottom of the opening.
2. Create a furrow in the mortar to help the brick settle properly.
3. Apply mortar to one side of the replacement brick.
4. Place the brick, wiggling it into position.
5. Gently tap the brick with the back of the trowel or hammer to align it with adjacent bricks.
6. As the hole gets smaller, switch to a flat pointer tool for the mortar.
7. Continue this process with the rest of the replacement bricks until the patch is complete.

McCullough stresses the importance of not using too much mortar, as excess can block weep holes and trap moisture behind the wall. Double-check the alignment of the bricks with the existing pattern.

Brick Wall Finishing Touches

The final steps in patching a hole in a brick wall involve filling joints and matching the existing mortar pattern.

Fill Joints

Using the flat pointer, begin filling in every joint as deeply as possible to create a strong bond and ward off water damage. Carefully press the mortar into the joints and smooth it out to match the contours of the existing mortar.

Match Existing Mortar Pattern

Here’s how to blend your repair with the existing wall:

1. Use a masonry jointer that matches the profile of the existing joints.
2. Smooth the mortar joints to match the surrounding pattern.
3. Brush off excess mortar from the face of the bricks with a masonry brush.

McCullough notes that while the new mortar may appear darker initially, it will lighten to match the existing mortar as it cures over the next few weeks. Close attention to detail in matching your mortar adds to your patch’s structural integrity and helps it blend in.

Additional Considerations for a Brick Wall Repair

A few logistical elements, such as climate, safety, and cleanup, are worth understanding. Let’s go over each one in more detail.

Weather Conditions

While working on the repair, consider weather conditions. Mortar sets better in moderate temperatures and can be negatively affected by extreme cold or heat. Protect your work area from rain and direct sunlight with a tarp to allow the mortar to cure properly.

Safety Precautions

Always prioritize safety. Wear safety glasses to protect your eyes from dust and debris, and utilize a dust shroud and HEPA vacuum to minimize harmful dust inhalation. Use gloves to protect your hands while handling tools and materials.

Tool Maintenance

Taking care of your tools leads to a smoother repair process. Clean your tools immediately after use to prevent the mortar from drying and bonding to them. Well-maintained tools are more efficient and safer to use.

Tips for a Professional-Looking Brick Repair

To achieve a repair that seamlessly blends with the existing wall, heed these tips:

• Allow the mortar to set slightly before tooling the joints for a cleaner finish.
• Clean any mortar smears from the face of the bricks immediately to prevent staining.
• Pay attention to the existing bond pattern and replicate it in your repair.
• Take time to find bricks that closely match the color and texture of the existing ones.

Pro Tip: Before applying new mortar, brush water on both the old and new bricks where the mortar will go. As This Old House Magazine advises, this prevents water from being sucked out of the mix and interfering with its cure. When mixed to the right consistency, the mortar should stick to the underside of the trowel.

When filling joints on a patch repair, push the mortar in as far as possible — unlike building a new wall, you won’t have the opportunity to lay a traditional bed joint. Once the mortar has firmed up slightly, use a brick brush to clean the surface, then slick the joints for a finished look. Keep in mind that fresh mortar will appear darker than the surrounding wall, but after about 28 days of curing, it should lighten and blend in with the existing joints.

Common Brick Wall Challenges and Solutions

When patching a hole in a brick wall, you may run into some challenges.

Here are McCullough’s solutions to three common issues:

• Crumbling mortar: If the surrounding mortar is weak, you may need to repoint a larger area for a lasting repair.
• Mismatched bricks: If you can’t find an exact match, consider weathering new bricks to blend better with the old.
• Water damage: Address any underlying moisture issues before patching to prevent future damage.

By staying ahead of these challenges and preparing accordingly, you can overcome obstacles and complete a successful repair.

Our Conclusion

Patching a hole in a brick wall is a manageable DIY project that can significantly improve your home’s appearance and structural integrity. With the right tools, materials, and techniques, any homeowner can get professional-looking results. Remember to prioritize safety by using dust control measures, and take your time.

Expert assistance with this segment was provided by MJM Masonry.

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