What Is Spalling Brick, and How Do You Deal With It?

While brick is a long-lasting, low-maintenance building material, it is not indestructible. Over time, weather and exposure can break bricks down. “Many people think of masonry as timeless and permanent,” Ray Wysack from Batchelder and Collins says. This leads to the misconception that you only have to keep the brick clean.” The reality is that bricks must be regularly inspected for deterioration or damage. A common issue to look for is spalling, which occurs when a brick disintegrates and crumbles apart.

During an annual inspection, I discovered my chimney had a few spalling bricks. After remedying the underlying moisture issue, I was able to promptly repair it following the steps in this article.

Read on to learn how to identify spalling bricks, how to prevent it from happening and how to repair it if it does. Also, find tips from seasoned masonry pros — Wysack and Hind Domanowski from Priddy Chimney Solutions — on how to deal with spalling bricks.

What Is Spalling Brick?

Spalling is a type of brick deterioration where the surface flakes off and reveals a rough, uneven layer. It can have a powdery, dusty texture or have missing chunks of brick if the problem progresses. “To the touch, a spalled brick will feel brittle and crumbly,” Domanowski says.

What Causes Spalling Brick?

“Spalling occurs when the masonry structure has absorbed a significant amount of moisture, usually because the brick has deteriorated or mortar joints have been damaged,” Domanowski says. In colder climates, this moisture freezes and expands, fracturing the brick over and over until the brick disintegrates.

Spalling happens in milder climates, too, as prolonged exposure to moisture softens brick and leads to deterioration. “Freeze-thaw cycles exacerbate spalling but are not necessary for the condition to occur,” Wysack says.

If you have a single spalled brick, this is likely a soft brick that was unintentionally installed. However, several or many failing bricks indicate a water intrusion problem. This was the case with my chimney.

Occasionally, spalling can also be the result of cleaning with a high pressure washer, salt exposure or incorrect mortar installation.

Is Spalling Brick Dangerous?

Yes. Spalling brick is not structurally sound and can lead to collapse if the problem is widespread.

“We recommend that spalling brick be addressed as soon as possible to help prevent a ‘domino effect’ where the compromised brick allows further moisture intrusion into the structure, thereby degrading adjacent bricks,” Domanowski says.

How To Prevent Spalling Brick

The first line of defense to prevent spalling brick is an annual masonry inspection to identify any developing issues. “Catching minor issues early can help avoid thousands of dollars in repairs,” Domanowski says.

In addition, follow these prevention methods:

• Provide proper drainage, weep holes and coping for brick retaining walls.
• Use a low-pressure setting when power washing.
• Regularly apply a breathable masonry sealant. “These slow moisture absorption and hinder the formation of mold and mildew,” Domanowski says.
• Install a rain cap on your chimney.
• Direct gutter downspouts away from brick foundations or walls to ensure proper drainage.
• Prevent moss and climbing plants from taking root on brick surfaces. “Vegetation will erode your masonry,” Domanowski says.

How To Replace Spalling Brick

While replacing a few spalled bricks is a manageable DIY project, the challenge lies in blending the new work with the old. “Matching the mortar as well as the brick will be difficult,” Wysack says. “There is a steep learning curve to do a job that blends well.”

For visible repairs on the front of your home, Wysack recommends hiring an experienced pro.

1. Remove existing mortar and brick

Use a hand chisel and a hammer, or a demolition hammer with a chisel bit to carefully remove vertical mortar joints. Cut horizontal mortar joints using a cut-off saw with a diamond blade. Always wear a respirator mask and goggles when cutting mortar as silica dust is hazardous.

Once the mortar is removed, pull the damaged brick away and discard. Use a leaf blower or vacuum to thoroughly remove dust and dirt from the opening.

2. Replace mortar and brick

Mix mortar following product directions. Use a trowel to place a small amount of mortar on the bottom of the opening. Lay the new brick onto the mortar. Use your trowel to move the brick until you attain consistent joints and face depth with neighboring bricks.

3. Finish the mortar joint

Use a grout bag to add mortar to the remaining joints. “This allows you to insert the mortar into the back of the brick and avoid having it stain the face,” Wysack says.

Let the mortar set slightly, then with a masonry slicker (narrow hand tool), press the mortar into the surrounding mortar joints. “If the mortar is not compressed before tooling it will not be nearly as strong or resilient,” Wysack says.

4. Tool the mortar

Test the mortar’s dryness by pressing it with your finger. If your finger stays clean, Wysack says it’s ready to be tooled. Use a jointing tool to smooth the mortar to match the existing tooling pattern. Wait a few minutes, then scrape away any excess mortar, taking care not to smear any on the brick face.

5. Let the mortar cure, then clean the brick

After a day, the mortar will be cured. Any mortar on the brick face can be cleaned without disturbing the repair.

FAQ

Is spalling brick covered by insurance?

No, spalling brick caused by weather, aging or poor home maintenance practices will not be covered by homeowner insurance.

Can you render over spalling bricks?

Yes, you can render over spalling bricks, but it’s not recommended. “Rendering or ‘parging’ over spalled brick runs the risk of trapping moisture in the bricks,” Domanowski says. “This leads the rendered layer and underlying brick to crack, exactly the outcome most would want to avoid.”

Render also cannot be removed, so total replacement is necessary in the event of failure. A better idea is to replace damaged bricks instead.

About the Experts

• Hind Domanowski leads the Priddy Chimney Solutions‘ sweep and masonry teams. With over 17 years of experience, she has a vast knowledge of the available masonry types and designs in the mid-Atlantic region, as well as a keen sense of how best to rescue troubled structures.
• Ray Wysack works in Outside Sales for Batchelder and Collins, a masonry, hardscape and veneer distributor in Virginia. Before this position, he was a mason for 15 years, specializing in repair and restoration.