Spalling Brickwork? Tackle it with Thompson’s

Spalling brickwork is a common problem in the UK, especially in older homes. It happens when the surface of bricks starts to flake, crumble or break away, often caused by water getting into the brick or mortar. Once moisture gets inside, cold weather can make things worse. The cycle of freezing, expanding, thawing and re-freezing can put pressure on the brick, until small pieces begin to chip off.

Water can seep in through several routes, including cracked mortar, porous bricks or weathered joints. Constant battering from rain, rising damp or leaking gutters only speeds up the damage. 

There’s another hidden culprit, too - non-breathable sealants. These can trap moisture inside the wall, stopping it from evaporating. What seems like a quick fix can actually make things worse in the long run.

Spalling brickwork can be an expensive problem 

Once moisture gets inside, the freeze-thaw cycle kicks in. In winter, trapped water freezes and expands, pushing the brick’s face outward. Repeated cycles like this slowly break down the structure. If left unchecked, spalling may lead to serious structural issues and expensive repairs.

In fact, spalling brick repair in the UK typically costs between £12 and £26 per brick (Checkatrade), with heritage brickmakers (often required to repair older properties) costing even more. Even just 10 damaged bricks could set you back up to £260 - and that’s before you factor in labour or scaffolding. Surveys often flag spalled brickwork on older properties, especially Victorian terraces and parapet walls. A small issue can escalate quickly if left untreated.

Prevention is better than cure

Before things get to this point, it’s important to rewind the clock and stop spalling brickwork in its tracks, focusing instead on prevention. 

Before applying any treatments, crumbling bricks or loose mortar should be repaired or repointed first - sealing over damaged areas won’t solve the problem.

Once you have the all-clear, start by cleaning the brickwork using Thompson’s Advanced Brick & Mortar Cleaner. This helps remove any algae, dirt or salt deposits that may retain moisture. The cleaner is easy to use - simply apply to wet surfaces, leave it to do its job for five to ten minutes, then scrub with water and a brush and rinse it away. After cleaning, allow the wall to dry completely before applying any sealant.

Once clean and dry, protect the brickwork with Thompson’s One Coat Water Seal. This product penetrates deep into the surface, creating an invisible, breathable barrier that repels water while still allowing trapped moisture to escape. Apply it with a brush or roller, working in one metre sections from the bottom upwards. One coat is usually enough and it begins working within hours, offering protection that can last for years.

Protect brickwork for the long term

By cleaning and sealing properly - and maintaining exterior brickwork every few years - you can prevent further spalling and keep a home dry, safe, and looking great for longer. Spalling might be common, but with the right approach, it's easy to stay on top of.