The wall that fails
before the
house does.
A free standing wall gets weather on both faces and along the top, and it has no roof. It is the most exposed masonry you own, and it is the most often repaired in a way that makes it worse.
No roof, and weather
on both sides.
Every wall on your house is protected by something. A garden wall is not. Rain hits both faces, runs along the top, and soaks in from above. There is no overhang, no flashing and no roof, so water enters from three directions and the wall never fully dries.
Add freezing. Saturated brickwork in a London winter freezes, the water expands, and it takes the face off the brick. That is why garden walls spall and crumble while the house wall a few metres away is untouched.
The foundations are usually the other half of the story. Garden walls were frequently built on very shallow footings, sometimes little more than a widened course of brick. On London clay, which shrinks in dry summers and swells again in winter, that is enough to produce the leaning and stepped cracking you see on almost every street.
Tree roots make it worse. A tree within roughly one and a half times its mature height of the wall is drawing moisture out of the clay in summer, and the ground under the wall drops.
Most walls fail
from the top down.
The coping is the course along the top of the wall, and its job is to throw water clear of the faces rather than let it soak down into the core. It is the wall's only roof.
When copings crack, become loose, or lose their bedding mortar, water goes straight down inside the wall. From there it works outwards, blowing brick faces and washing mortar out from the middle. By the time you can see damage on the faces, the core of the wall has often been wet for years.
This is why so many garden wall repairs fail. Somebody repoints the faces, which looks like the problem, and leaves the coping. Water keeps arriving from the top, and the new pointing fails in the same place within a few winters.
If you are going to spend money on one part of a garden wall, spend it on the top. Rebedding loose copings and making sure there is a proper drip is unglamorous and it is what determines whether the rest of the work lasts.
When it stops being
a repair.
A slight lean that has not moved in years may be stable and historic. A wall that is bulging in the middle, or where the two faces have separated so the core is loose, is a different matter, because a free standing wall relies on its whole thickness acting together.
There is a safety dimension here that is easy to underplay. A brick garden wall is heavy, and a collapse onto a pavement, a car or a person is a real liability. Walls adjacent to a highway deserve more caution than walls at the bottom of a garden.
Signs worth acting on are a lean that is visibly increasing, a bulge you can see by sighting along the wall from one end, mortar joints open on one face and closed on the other, and vertical cracks near piers.
Sometimes the correct answer is taking the wall down and rebuilding it on proper foundations, reusing the original bricks where they are sound. That is more expensive than patching and it is the only thing that resolves a foundation problem, and patching a wall that is moving is money spent twice.
Two things to check
before anyone starts.
In a conservation area, permitted development rights for demolishing a wall are restricted. As a general guide, demolition tends to be caught where a wall is over one metre high adjacent to a highway, footpath or open space, and over two metres elsewhere, and case law has established that partial demolition can trigger the same protection as taking the whole thing down. Notting Hill, Holland Park, Kensington and much of west London are covered by conservation areas, so this is not an edge case.
The second question is whose wall it is. A wall standing astride the boundary line is a party fence wall under the Party Wall etc. Act 1996, and work to it requires written notice to the adjoining owner, generally at least one month before starting. A wall wholly on your own land does not.
Neither of these is a reason not to proceed. Both are reasons to establish the position before work starts rather than after a neighbour or the council raises it, because that is when a straightforward job becomes an expensive one.
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Areas we cover.
We take garden and boundary wall repairs across all 32 London boroughs. Most of our work is in west London, in Shepherd's Bush, Hammersmith, Fulham, Kensington, Chiswick and White City, and in south west London, in Putney, Wandsworth and Wimbledon. We also work in south east London, in Greenwich, Blackheath and Lewisham.
If your property is outside these areas, call us anyway. We travel across London and will tell you honestly if a job is too far to price properly.