Frost damages garden walls when water soaks into bricks and mortar, freezes, expands and slowly breaks them apart. The early signs are flaking brick faces, crumbling mortar joints and loose coping stones. Caught early, most walls can be repaired by clearing drainage, replacing damaged bricks and repointing. A wall that’s leaning or cracked right through needs proper attention before it gets worse. Our brickwork team builds and repairs garden walls across Essex, including homes around Epping and Ongar.
How frost damages brick and mortar
Bricks and mortar are porous. When it rains, they absorb water. On a frosty night, that water freezes and expands, putting pressure on the material from the inside. When it thaws, the water moves a little deeper. Repeat that cycle through a cold winter and the surface starts to break away.
Garden walls take more of this than house walls. They’re exposed on both sides and on top, there’s often no roof overhang to keep the rain off, and soil can be piled up against them, keeping the lower courses damp for months.
Signs of frost damage to look for
Walk along your walls after a cold spell and look for:
- Spalling, where the face of a brick flakes or pops off, leaving a rough, crumbly surface
- Soft or sandy mortar that you can scrape out of the joints with a key
- Cracks running through bricks or along mortar joints
- Loose or missing coping stones or bricks along the top of the wall
- White, powdery deposits on the surface, called efflorescence, which show water moving through the wall
- Damp patches that stay long after rain has stopped
- A lean or bulge, especially in retaining walls holding back soil
A few flaking bricks are common on older walls. Widespread damage, or any movement in the wall, is a sign that it needs looking at.
What causes some walls to suffer more
The wrong bricks or mortar
Not all bricks are made to cope with heavy exposure to frost. Bricks used in exposed places, such as copings, retaining walls and the bottom courses near the ground, need to suit those conditions. Mortar matters too. A mortar that’s much harder than the bricks can trap water in the brick and lead to the face breaking away instead of the joint.
Water getting in from the top
Damaged or missing copings let rain soak straight down into the wall. Fixing the top of the wall is often the first and most important repair.
Soil and poor drainage
Soil piled against a wall, or a retaining wall without drainage behind it, keeps the bricks wet. Wet bricks freeze more readily and suffer more damage.
Repairing a frost-damaged wall
The right repair depends on how far the damage has gone:
- Repointing replaces crumbling mortar in the joints with a suitable new mix
- Replacing spalled bricks removes damaged bricks and fits new ones that match
- Refixing or replacing copings stops water getting into the top of the wall
- Improving drainage behind and beside the wall keeps it drier in future
- Rebuilding may be the best option for a wall that’s leaning, badly cracked or failing at the base
If a wall is leaning, bulging or has a crack that’s getting wider, keep children and pets away from it and get it checked. Don’t lean ladders or heavy items against it.
Garden walls in Epping, Ongar and the surrounding area
Many older properties around Epping, Ongar and Brentwood have original garden walls that have weathered decades of Essex winters. Large parts of the county sit on clay soil, which swells when wet and shrinks in dry summers, so walls with shallow footings can move and crack over time, giving frost an easy way in. Low walls around patios and raised beds are often the first to show wear, because they’re surrounded by damp soil and paving.
Frequently asked questions
Can frost-damaged bricks be repaired?
Lightly damaged bricks can sometimes be left if the damage is only on the surface, but bricks that have lost their face will keep deteriorating. The usual repair is to cut them out and replace them with matching bricks. Fixing the cause, such as broken copings or poor drainage, stops the same thing happening again.
When should a garden wall be repointed?
Repointing is worth doing when the mortar is soft, crumbling or recessed well back from the face of the bricks. It’s usually best done in milder, drier weather, as fresh mortar can be damaged by frost before it sets. Planning the work over winter and carrying it out in spring is common.
Is a leaning garden wall dangerous?
It can be. A leaning wall may have failing footings, tree root pressure or soil pushing against it, and it can collapse without much warning. Keep people away from it, particularly children, and don’t put extra weight against it. Have it inspected so you know whether it can be repaired or needs rebuilding.
Get your garden walls checked
If your garden wall is crumbling, cracking or starting to lean, give us a call on 01277 824 093 or drop us a message and we’ll come and take a look and explain whether it needs a repair or a rebuild.