Spalling brickwork is a common issue affecting thousands of buildings across the UK. While it often starts as a cosmetic concern, if left untreated, it can escalate into more serious structural problems.
But really, what is spalling? Why does it happen, and how can you identify it? In this piece we’ll look at all of the above as well as potential methods to help fix and prevent it effectively.
What is spalling brickwork?
Spalling refers to the flaking, cracking, peeling, or crumbling of bricks where parts of the surface break away from the main body. Over time, this damage exposes the softer inner parts of the brick, making them more vulnerable to environmental stress and accelerating decay.
Though it may be noticed initially as an aesthetic problem, with it leaving walls looking weathered or patchy, in more severe cases it can lead to structural issues that compromise the integrity of the building.
What causes spalling bricks?
The primary cause of spalling brickwork is water ingress which is the absorption of moisture into the brick. While bricks make for solid building components in construction, they’re not waterproof. Bricks are porous, meaning they naturally absorb and retain water.
In cold weather, the absorbed water freezes and expands which creates internal pressure within the brick, causing the surface to crack or “blow” away. As more water enters through the newly formed cracks, the cycle continues, progressively worsening the damage, a process known as the freeze-thaw cycle.
However, this freeze-thaw cycle is not the only cause for spalling bricks, there are a number of other contributing factors that can cause spalling.
Not only is moisture a concern for brickwork due to the freeze-thaw process, but moisture can also carry salts that crystallise just beneath the brick surface, leading to cracking and flaking, especially in reused or low-quality bricks. This is called cryptoflorescence or salt crystallisation.
Poor mortar selection is another key contributor to spalling. In the construction process, using hard cement mortar instead of breathable lime mortar can create issues later down the line as the hard cement forces trapped moisture to escape through the brick face, accelerating spalling.
Another somewhat unavoidable factor is aging brickwork. We’re all susceptible to the passage and ravages of time, and bricks are no different. Older bricks often become more porous over time, increasing their susceptibility to water damage.
While aging bricks in pre-existing structures are understandable, sometimes a contributing element to spalling brickwork is when there has been poor construction or repairs, often using salvaged bricks. Other underwriting poor construction works include poor pointing or improper curing which can all contribute to premature spalling.
In terms of underlining environmental risks, in the UK, north-facing walls are considered particularly susceptible, especially in the drearier months where the classic British weather can go from drizzle to downpour to frost all in the span of a week. Areas near leaky gutters or foundations are particularly vulnerable to spalling as they are more exposed to moisture.
How to spot spalling brickwork?
Signs of spalling tend to be quite noticeable, so you should keep an eye out for:
- Chipping or flaking surfaces
- Peeling brick faces (sometimes they look like they’ve “blown off”)
- Cracks or crumbling mortar
- Discolouration or moss/algae growth
- Damp patches on internal walls (especially in older or solid wall homes)
These are not just cosmetic red flags; they’re often indicators of ongoing water damage within the masonry.
What happens if you ignore spalling?
While minor spalling may seem harmless, over time, untreated brickwork can lead to:
- Worsening structural damage as water keeps getting in, making things worse with every freeze-thaw cycle. Severe spalling can compromise the integrity of walls, leading to collapsed brickwork.
- Penetrating damp: Moisture can pass through the outer wall into internal spaces, causing damp patches, black mould, and damaged plaster, especially in solid wall properties.
- Increased heat loss: Saturated bricks lose insulation effectiveness. Just 5% moisture can cut insulation by 50%, increasing heating bills and your carbon footprint.
- Accelerated decay: Moisture attracts organic growth and further weakens the brick structure, setting off a cycle of deterioration.
How to fix spalling brickwork?
Don’t worry, it’s not all doom and crumbling gloom. There are ways to fix spalling, depending on how bad it has become.
For less serious damage, a brick slip (basically a slim brick veneer) can be fitted over the affected area using adhesive to match the surrounding brickwork. This is a quicker and less invasive repair for small areas of aesthetic damage.
For more severe cases, the damaged brick will have to be removed by carefully cutting out the damaged brick using a hammer, chisel, or power tool and replaced by a new matching brick and fresh mortar. If you’re a dab-hand at DIY this is possible to do yourself, however if you’re unsure you may want to acquire the help of a professional.
For large-scale or structural damage, consult a qualified brickwork specialist to ensure safety and quality.
How to prevent spalling brickwork?
The key to prevention is stopping water from getting in while still allowing trapped moisture to escape. Here are some ways to do so:
- Check your pointing, replacing hard cement with lime mortar where possible.
- Fix leaky gutters and downpipes as they’re common culprits of saturated walls.
- Ensure proper drainage around the base of your house.
- Tackle moss and algae early, they thrive on damp brickwork and hint at bigger problems.
- Waterproofing with breathable treatments that repels rainwater but still allows trapped moisture to escape, such as masonry crème.
Spalling brickwork may sound like just another home maintenance hassle but tackling it early can save you from bigger issues down the line. Spalling brickwork is more than just an eyesore. It’s a visible sign that your building is under attack from moisture, and if not addressed, it can lead to severe damage and costly repairs. Fortunately, with the right knowledge and materials, spalling can be repaired and prevented.
Protecting your property starts with proper maintenance! Whether you’re dealing with an old Victorian terrace or a modern build, staying ahead of spalling is essential for preserving the appearance, efficiency, and safety of your brickwork long term.
If you’re interested in commissioning a home survey for you property purchase to highlight potential concerns or defects, get in touch!