Top Retaining Walls Lower Hutt builds reinforced concrete block retaining walls across Lower Hutt. Blocks sit on a concrete footing with steel running up through the cores, and once those cores are grout filled the footing, the steel and the block all work as one structure. It is the wall you build when what sits above it matters.
We excavate to firm bearing and pour a reinforced footing with starter bars standing proud of it. The blocks thread down over those bars course by course, horizontal steel ties in as the wall rises, then the cores get grout filled so everything acts together.
The drainage layer goes in behind before any backfill, because once the wall is up you cannot get back there. Clean metal, a coil at the base, geotextile over the top.
| Footing | Reinforced concrete, excavated to firm bearing |
|---|---|
| Blocks | Standard masonry units, grout filled cores |
| Steel | Vertical starters from the footing, horizontal bars as it rises |
| Drainage | Free draining metal, drain coil, geotextile, weep holes where used |
| Height | Engineered design and consent above 1.5m or with any surcharge |
| Seismic | Designed for the Wellington hazard, not a generic case |
| Finish | Bare, plastered and painted, or sealed |
The Wellington Fault runs along the western edge of this valley, and the whole region sits on a plate boundary. Any engineered wall here carries a seismic case as well as a static one, and the design will usually be more conservative than the same wall would be in a lower hazard part of the country.
Reinforced block takes that well. The steel is visible to the inspector before the grout goes in, which keeps the consent process simple compared with wall types where the structural work disappears as it is built.
Anything retaining more than 1.5m needs a building consent from Hutt City Council and a chartered engineer's design. So does a shorter wall with a surcharge, which means a driveway, a building, a pool or sloping fill above it.
Block is the type we most often build to drawings, partly because it takes reinforcing easily and partly because it suits the ground on both the flat and the hill.
Bare grey block is honest and cheap. Plaster and paint gives a clean modern face and hides the joints. Either way we recommend sealing masonry, because persistent moisture brings efflorescence and staining out through the face, and moisture is not in short supply here.
We cap the top course, which keeps water out of the cores and makes the top line look deliberate rather than simply cut off.
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.
For the same height, by a wide margin once it is reinforced and grout filled. It also carries surcharge that timber cannot, which is why driveway walls are block or poured concrete.
Some designs use them, others rely on the coil at the base. Either way the point is the same, which is giving water a way out before it can push on the wall.
Yes, and it is often the right call. Hill sections here need engineering anyway because of slope and height, and block takes an engineered design cleanly.
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.
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