Timber Retaining Walls
Timber is what most Christchurch sections end up with, and for good reason. A pole and rail wall goes up in a few days, costs less than block, and holds a 1.2m.
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Sumner, Canterbury
Retaining Walls in Sumner
Top Retaining Walls Christchurch builds retaining walls in Sumner, Redcliffs, Moncks Bay and Clifton, where almost every job is a hill job. Sumner sits at the seaward end of the Port Hills, so sections are steep, driveways are steeper, and the ground is loess sitting over volcanic rock.
- Timber, block, gabion, stone and engineered walls
- Full drainage behind every wall we build
- Consents lodged through Christchurch City Council
- Drainage on every wall300mm of metal, a drain coil and geotextile. Never an optional extra.
- H5 poles as standardThe right treatment for timber that lives in wet ground.
- Consents handledChristchurch City, Selwyn and Waimakariri, start to finish.
- Itemised quotesYou see what the drainage and the spoil actually cost.
Loess is the reason Sumner walls need engineering
Loess is wind blown silt, and dry loess is deceptive. It stands up in near vertical faces and feels solid, which is why people underestimate it. Wet loess loses that strength, and the loess colluvium around the base of the Port Hills was directly involved in the ground movement recorded here after the February 2011 earthquake.
The practical result is that most Sumner walls need a chartered engineer, both because of height and because sloping ground counts as a surcharge. We work on the assumption that a Sumner job is a consented job until the site proves otherwise.
| Council for consents | Christchurch City Council |
|---|---|
| Typical ground | Port Hills loess over basalt, steep |
| Walls we build most here | Engineered block, gabion and stone |
| Consent threshold | 1.5m of retained ground, or any surcharge above the wall |
| Drainage | 300mm metal, perforated coil, geotextile, on every wall |
| Site visit | Free, with a written quote to follow |
Salt air changes the materials we use
Bare galvanising corrodes faster near the coast. On gabion work in Sumner we specify PVC coated mesh rather than plain galvanised, and on any wall we use hot dip galvanised or stainless fixings rather than the cheaper alternatives.
Concrete and stone are unbothered by salt air, which is one reason block, gabion and basalt walls are so common on this side of the hill.
Access on Sumner sections is its own problem
Steep, narrow driveways and sections that fall away sharply behind the house make machine access hard. Sometimes the only way in is a small machine walked down in stages, and spoil has to go back up the same way.
That is real cost and we would rather show it to you honestly at the quote than discover it on day two. Send photos looking up and down the slope with your enquiry.
Not sure whether your wall needs a consent? Send us a photo and a rough height. Under 1.5m of retained ground with nothing loading it from above is exempt. A driveway, a building, a pool or fill sloping up behind it is a surcharge, and that changes the answer.
Common questions
Retaining walls in Sumner: common questions
Do Sumner retaining walls always need consent?
Not always, but often. Sloping ground above a wall is a surcharge, and combined with typical Port Hills wall heights it puts most jobs here into consent territory.
What wall type is best for a Sumner section?
Engineered block, gabion or stone. Gabion handles ground movement well and drains completely. Block takes an engineered design cleanly. We match the answer to the slope and the load.
Wall types
Retaining walls we build in Sumner
Concrete and Block Retaining Walls
Concrete lasts longer than timber and carries far more load, which is why it goes in wherever a driveway, a shed or a neighbour's lawn sits above the wall. We build.
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Engineered Retaining Walls
Once a wall passes 1.5m, or once a driveway or building sits above it, the job changes. You need a chartered engineer, a building consent and inspections. We manage.
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Stone and Gabion Retaining Walls
Stone is the choice when the wall has to look like it belongs. Canterbury gives us plenty to work with, including Halswell basalt, Port Hills volcanic stone, Timaru.
See moreNeed a retaining wall in Sumner?
Answer three quick questions or call [PHONE] and we will book a free site visit.