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Repairing cracks in brick walls: Everything you need to know

If you've ever wondered why walls crack and what goes into repairing cracks in brick walls, keep reading. By the time you finish reading, you'll know everything there is to know about the restorative world of bricks and mortar.

Builders have been repairing cracks in brick walls since the dawn of construction. Once purely structural, brick walls are now used in a variety of ways, including for feature walls and aesthetic loft conversions.

Although they’re known for their durability and timeless appeal, these sturdy structures aren’t immune to the ravages of time. As a result, they develop cracks that cause potential structural issues and compromise your home’s overall design appeal.

So, keep reading while we will explore the different types of cracks found in brick walls, their causes, and our tried and tested ways to repair them. We’ll also look at when it’s worth seeking professional help from a builder and how much that might cost you.

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Common types of cracks in brick walls

Your brick wall is cracked. That’s why you’re here. However, before we dive into the repair process, we’re going to teach you how to identify the different types of cracks commonly found in brick walls. Once you know the type of crack you’re dealing with, you can repair it in the best way.

Hairline cracks

Aptly named, these cracks are very fine – typically less than 1mm wide. They’re often superficial and don’t indicate a major structural problem. However, if you’re not a fan of the aesthetic, they’re easy to fill and repair.

Vertical cracks

A vertical crack in your brick wall will usually start from the top and run to the bottom. They may occur because you live in a new-build and your house is ‘settling.’

Other causes include significant changes in temperature or the natural ageing process of your property. While they don’t tend to pose an immediate threat, you need to address them to prevent further damage.

Diagonal cracks

Diagonal cracks suggest your home’s foundations have moved or it’s suffering from structural stress. They often indicate a cause for concern and require immediate professional attention.

Horizontal cracks

Horizontal cracks are a red flag for potential structural issues. They can indicate excessive pressure against the wall, which may require immediate professional intervention.

 Tradesperson building a brick wall and using a spirit level. Image used in blog on repairing cracks in brick walls.

Causes of cracks in brick walls

Understanding what causes cracks to appear in the first place is crucial for preventing their recurrence after you’ve repaired them.

  • Settlement: The ground beneath your property may shift over time, causing the foundation to settle. This settling exerts pressure on the walls, leading to cracks.
  • Thermal expansion and contraction: Fluctuations in temperature, especially during freezing and thawing cycles, cause bricks to expand and contract, leading to cracks.
  • Moisture damage: Water infiltration due to leaky pipes, faulty gutters, or inadequate waterproofing weakens the structural integrity of the bricks, resulting in cracks.
  • Poor construction or design: Inadequate structural support or improper mortar mix during construction can contribute to cracks in the brickwork.

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Repairing cracks in brick walls

When it comes to repairing cracks in brick walls, act fast to prevent further damage. Here’s our handy step-by-step guide to get you started.

Step one: Assess the severity

Start by assessing the size, direction, and location of your brick wall’s cracks. Note any signs of structural movement or instability, such as bulging or unevenness in the wall.

Step two: Prepare the area (and yourself)

Throw on your overalls and clean the cracked area/s using a stiff brush. This will remove any loose debris, dust, or mortar and help ensure a good bond for the repair material of your choice.

Step three: Fill in the cracks

For hairline cracks, use a specialised brick sealant or mortar repair caulk (available at your local hardware store).

Apply the product with a caulking gun, taking care to follow the manufacturer’s instructions. For wider cracks, use a brick-compatible epoxy filler or mortar mix, which you firmly push into the crack/s with what’s called a ‘pointing trowel.’

Step four: Smooth and blend

After filling the cracks, put on your artist cap and use a trowel or a brush to smooth and blend the repair material with the surrounding brickwork. This will help create a seamless appearance.

Step five: Allow for curing time

Follow the manufacturer’s instructions regarding curing time for your repair material of choice. Make sure no one disturbs the area during this period.

Step six: Apply a protective sealant

Once the repair has fully cured, consider applying a breathable sealant to the entire wall. This will help prevent future moisture damage while extending the lifespan of your hard work.

Step seven: Congratulate yourself for fixing the cracks in your brick walls

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Additional tips for brick wall crack repairs

Reinforce your walls

In cases where cracks are indicative of ongoing structural issues, a builder may suggest reinforcing your brick walls.

This may involve adding steel bars or installing wall ties to strengthen the affected areas and prevent further movement.

Get a professional assessment

If you have any doubts about the severity or cause of the cracks, it’s always best to seek some professional advice from a qualified builder.

They’ll give you an accurate diagnosis, identify underlying issues, and propose suitable repair strategies.

Perform regular maintenance

To minimise the occurrence of cracks in your brick walls, make sure you undertake regular maintenance.

This includes inspecting the walls for signs of damage, addressing any water leaks promptly, and maintaining proper drainage around your home’s foundations.

Brick splashback

Brick wall crack repair cost

The exact cost of repairing a cracked brick wall varies significantly depending on factors such as the severity and extent of the damage, the location of the cracks, your wall’s accessibility, and your location.

However, it’s worth looking at some estimates to see how much you can expect to spend on fixing cracks in your brick walls.

DIY repair costs

For minor cracks, such as hairline cracks you can repair yourself, costs only include the materials needed (e.g., mortar mix, brick sealant, or epoxy fillers).

These materials range from £10 to £50 depending on the type and quantity required.

NB: If you don’t already own the necessary tools, you’ll need to invest in a pointing trowel or a caulking gun, which adds to the overall cost.

Professional repair costs

For more extensive or severe cracks, we advise hiring a professional and reputable builder to handle the repair work.

The cost of professional repairs depends on several factors, such as:

Assessment and consultation fees

Some builders charge a fee to assess the damage and provide an estimate for the repair.

This fee typically ranges from £50 to £150, depending on the complexity of the assessment.

Labour and material costs

The actual repair costs are calculated based on the time and materials required.

For brick wall repairs, builders often charge an hourly rate, which ranges from £20 to £50 per hour or £240 – £300 per day.

Material costs, such as mortar, sealant, or fillers, are often included in the overall estimate, which your builder will provide.

Additional factors

If the cracks are indicative of underlying structural issues or require more complex remedial measures, such as reinforcing the walls or addressing foundation problems, the cost will increase accordingly.

These repairs may involve additional specialist services, such as structural engineers or foundation experts, which will add to the overall price.

As a result, it’s worth asking for several quotes from reputable builders in your area to compare prices and services before making a decision.

Related content: Spalling brick repair cost guide.

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When to call a builder

Although repairing some minor cracks yourself saves money, there are times you’ll need to call a professional builder to reassure you your house won’t fall down.

Structural instability

If you notice significant structural movement, horizontal cracks, or signs of bulging or sagging, you need to contact a professional builder asap. They’ll assess your walls and recommend appropriate remedial measures.

Extensive damage

If the cracks cover a large area or you find them in multiple rooms in your house, it’s time to involve a builder. They have the expertise to handle complex repairs effectively.

Lack of experience

If you question your ability to assess or repair the cracks yourself, seeking professional help is wise. Builders have the necessary skills and knowledge to make sure your repair is carried out well and lasts a long time.

Exposed brick wall advantages

Final thoughts

Repairing cracks in brick walls requires careful attention and timely action to preserve both the aesthetics and structural integrity of your home.

By understanding the different types of cracks, and their causes, and following the appropriate repair steps outlined in this guide, you can successfully address minor cracks.

However, for more severe cracks and signs of structural instability, it is always best to consult a professional builder who can provide expert advice and carry out necessary repairs to ensure the safety and longevity of your home.

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How do I identify a vertical crack in my brick wall?

Vertical cracks are relatively common in brick walls and can occur due to a variety of factors. For example, settling, temperature changes, or even natural shrinkage of the mortar.

While vertical cracks aren’t always an immediate cause for alarm, be sure to monitor their progression. If the crack widens or shows signs of displacement, consult a builder for a thorough assessment. They’ll let you know whether the crack is superficial or indicative of more severe structural problems.

What is a zig zag crack in a brick wall?

Zigzag cracks, also known as stepped cracks, often appear in a diagonal pattern across the brickwork.

These cracks often need immediate attention as they sometimes indicate something called ‘differential settlement,’ which is when different parts of your home’s foundations settle at different rates.

This type of crack is best left for a professional builder to handle, who’ll be able to give it the appropriate diagnosis and attention.

What do settlement cracks in brick walls look like?

Settlement cracks typically appear as vertical or diagonal cracks and are often caused by the natural settling of your property’s foundation.

As the soil beneath the foundation shifts and compacts over time, it exerts pressure on the walls, which leads to cracks.

Small settlement cracks, such as hairline cracks, are usually harmless and addressed with simple repairs.

However, if settlement cracks become wider or show signs of progressive movement, it’s essential to involve a professional builder to evaluate the extent of the issue. They’ll also implement appropriate remediation measures.

Did you find this guide on ‘repairing cracks in brick walls’ helpful? If so, check out our blog for more how-tos, expert advice, and cost guides.

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