Top Retaining Walls Christchurch repairs retaining walls all over Christchurch, and we start every one of these jobs the same way, by working out whether the wall is worth saving. Sometimes it is, and the fix costs a fraction of a rebuild. Sometimes it is not, and we would rather tell you that than take your money twice.
The most common by a distance is drainage. Water sits behind the wall, the soil gets heavy, and the wall leans out a little more each winter. Second is rot, where the posts were never H5 or the drainage was missing, and they go at ground line where you cannot see it. Third is ground movement, which in Christchurch usually means earthquake related settlement, lateral spread on the flat, or slope movement on the hill.
Each one needs a different fix, and telling them apart is most of the job. A leaning wall with sound posts is a drainage problem. A leaning wall with soft posts is a rebuild.
| Common cause | Blocked or missing drainage, by a wide margin |
|---|---|
| Second cause | Post rot at ground line, often from wrong treatment level |
| Third cause | Ground movement, settlement or slope instability |
| Assessment | Free site visit, honest repair or rebuild call |
| Drainage retrofit | Excavate behind, install metal, coil and geotextile |
| Partial rebuild | One section of a longer wall where the rest is sound |
| Boundary walls | Written scope you can share with a neighbour |
We check whether the posts are still solid at ground line, whether the lean is uniform or worst in one spot, whether the drain coil is running, and what is happening to the ground above and below the wall. Tension cracks in the lawn behind a wall are a sign the problem is bigger than the wall.
If we think it is a slope stability issue rather than a wall issue, we say so and recommend a geotechnical engineer. Rebuilding a wall on moving ground just gives you a newer wall that moves.
Retrofitting drainage behind a wall that leans but is otherwise sound. Replacing individual rotted posts and re bracing. Replacing bulged or split rails. Clearing and re running drain coil that silted up because it was never wrapped in geotextile. Rebuilding one damaged section of a longer wall rather than the whole run.
On earthquake damaged walls we look at what actually moved. The MBIE review after 2011 found many wall failures started with slope instability above or below the wall rather than the wall itself.
Generally the owner whose land is being retained is responsible, because the wall is holding up their soil. In practice these get argued about, and both the Property Law Act and the Fencing Act can come into it. Christchurch City Council also publishes guidance on retaining walls associated with legal roads, where responsibility can be shared.
Get any cost sharing agreement in writing before work starts. We can supply a written quote and scope that both parties can look at.
Every wall we build gets drainage. At least 300mm of clean free draining metal, a perforated coil at the base running to a real outlet, and geotextile over the top so silt cannot block it. It is not an optional line on our quotes.
Not always. If the posts are still sound and the lean is uniform, retrofitting drainage often stops the movement and buys many more years. If the posts are soft at ground line, it needs rebuilding.
Yes, and we do that regularly. There is no sense rebuilding 20m when 4m has failed, as long as the rest is genuinely sound.
That is between you and your insurer, and it depends on your policy and the event. We can provide a written assessment and quote for your claim, but we cannot tell you what will be covered.
Our old wall was rotten right through and leaning into the neighbour's place. They pulled the lot out, put proper drainage behind the new one and had it finished in three days. Swept the site clean every afternoon before they left too. Tidiest crew we have ever had here by a long way.
They sorted the consent, which was the bit I was dreading. Dealt with the council so I never had to, and kept me in the loop the whole way through. The driveway sits right above it and has not shifted a millimetre.
Steep section, shocking access, and they still made it look easy. They suggested two smaller walls instead of one big one, which saved us thousands in engineering fees. The terrace in between is now my favourite part of the whole garden.
Call [PHONE] or answer three quick questions. The site visit and the written quote cost you nothing.
