Top Retaining Walls Christchurch builds timber, concrete block, gabion, stone and engineered retaining walls right across the city. Every wall we build gets a full drainage system behind it, because that is the part that keeps it standing straight in twenty years.
The right wall depends on how high it is, what sits above it and what the ground under it is doing. We build all four types, so we have no reason to talk you into the one we happen to like.
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 change in level without any trouble. We set 200mm H5 poles in concrete, backfill with clean drainage metal, and run a drain coil the full length so water leaves instead of pushing.
See timber 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 Keystone and Firth block walls, steel post and concrete sleeper walls, and poured reinforced walls. Engineered concrete walls came through the Canterbury earthquakes better than almost anything else.
See concrete and block 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 that whole run, from the first site visit through the design, the council application and the final sign off, and we build to the drawings rather than around them.
See engineered 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 bluestone and braided river boulders. Gabion baskets sit in the same family and cost less, and because they drain through the face they handle water better than almost any other wall.
See stone and gabion retaining walls
Nearly every failed wall we get called to in Christchurch failed the same way. Water sat behind it, the soil got heavy, and the wall leaned out a little more each winter. So we build the drainage first and the face second.
Five stages, in this order, every time.
We come out, measure the retained height, look at what sits above and below the wall, and check whether a machine can reach the wall line. Access changes the price more than the wall type does.
We work out whether your wall is exempt or needs a building consent. If it needs one, we brief the engineer and get the design and producer statement organised.
Itemised by wall length and height, drainage, spoil removal, and consent fees where they apply. Where the site allows it we price the tiered option too.
We dig, set posts or footings, build the wall, then install the drainage layer and backfill in compacted lifts. Concrete cures before anything gets backfilled against it.
We meet the council inspections on consented jobs, take the spoil away and leave the site tidy. You get shown the drainage outlet so you know where to check it.
Flat sections, steep sections, boundary runs and driveway walls.
Wall has been up two winters now and has not moved a bit. Rapt with it.
Rang three companies and these were the only ones who turned up when they said they would. Ended up doing 22 metres along the back boundary. The lawn is finally flat enough for the kids to kick a ball on, which was the whole point. Would have them back tomorrow.
Not the cheapest quote I got, but the only one where someone actually explained why the drainage mattered instead of just handing me a number. Two years on and the wall is dead straight. Money well spent and I would use them again without thinking about it.
Not if the wall retains 1.5m of ground or less and carries no surcharge. A surcharge means extra load above the wall, so a driveway, a parked car, a building, a pool or fill that slopes up behind it. Cross either line and you need a consent from Christchurch City Council plus a chartered engineer's design. We tell you which side you are on at the site visit.
Guide ranges around New Zealand for walls up to 1.5m run roughly 300 to 500 dollars a lineal metre for timber, 400 to 900 for concrete block, 400 to 700 for gabion, and from about 1000 for natural stone. Machine access to the wall line moves that number more than anything else, so we price it properly on site rather than guessing from a table.
It depends where you are. Flat western and northern suburbs sit on firm gravel and take timber or block easily. Eastern suburbs with a liquefaction history suit flexible systems like gabion. Port Hills sections in loess usually need engineering, and terracing is often smarter than one tall wall.
An H5 timber wall with working drainage commonly runs 25 to 40 years. The same wall without drainage can rot out in 10 to 15. Concrete, gabion and stone walls last considerably longer, which is why they cost more up front.
Generally the owner whose land is being retained, because the wall holds up their soil. In practice these get argued about, and both the Property Law Act and the Fencing Act can apply. Get any cost sharing agreement in writing before work starts.
A typical 10m to 15m timber wall takes two to four days on site, plus curing time before we backfill. Block and stone take longer. Consented walls add the council timeframe on top, and Christchurch City Council works to 20 working days from a complete application.
Three quick questions and your details. We will tell you what the wall needs, whether it will need a consent, and roughly what it costs. Then we come out and measure it properly.
