Top Retaining Walls Lower Hutt builds Firth Keystone retaining walls in Lower Hutt. Keystone is a segmental system, meaning the blocks lock together with fibreglass pins instead of mortar. The wall goes up dry, it follows a curve, and it flexes slightly rather than cracking when the ground moves, which counts for something in this part of the country.
Each Compac III block drops onto pins set in the course below, and the pin position sets the setback automatically. The wall leans back about 8 degrees as it rises, putting the mass of the blocks to work against the soil. There is no mortar and no grout in a standard build.
Firth rates a standard Compac III wall to 1m with that setback, provided there is no surcharge and no sloping toe. Above that the wall needs an engineered design, usually with geogrid layers running back into the fill.
| Block | Firth Keystone Compac III, rockface or straight face |
|---|---|
| Connection | Keystone pin system, no mortar |
| Setback | About 8 degrees, built in by the pin position |
| Standard height | Up to 1m with no surcharge and no sloping toe |
| Taller walls | Engineered design with geogrid layers into the fill |
| Base | Compacted granular levelling pad below finished ground |
| Finish | Sealing recommended where the wall stays damp |
Geogrid is a stiff plastic mesh laid horizontally between courses and extending back into compacted fill. It ties the block face to a large mass of soil behind, so the wall and the soil act together rather than the blocks trying to hold everything alone.
That is how you get a 2m or 3m segmental wall. It also means the excavation behind a tall Keystone wall is far bigger than people expect, which matters on a tight Hutt section. We show you the dig footprint at the quote so it is not a shock on day one.
Segmental block is the easiest way to build a curved wall. Each block pivots slightly against its neighbour, so a sweeping radius comes out smooth instead of faceted. Corner blocks and caps finish the ends properly.
This is why Keystone turns up so often on the flat through Waterloo, Fairfield and Avalon, where landscaping plans have curved beds and stepped terraces rather than straight boundary runs.
Compac III comes in a rockface and a straight face in more than one colour. Aggregate is sourced regionally so colour shifts a little by area, and we get samples on site before you choose rather than picking off a screen.
Firth recommends sealing masonry where a wall stays damp. On a shaded south facing wall in the Hutt that is money well spent.
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.
Firth rates a standard Compac III wall to 1m with the 8 degree setback, no surcharge and no sloping toe. Anything taller, or with load above it, needs an engineered design.
A stiff mesh laid between courses and running back into the fill. Taller segmental walls need it. It ties the blocks to the soil mass behind so the whole thing works as one.
Yes, and it is one of the real strengths of the system. The blocks pivot slightly against each other so a curve comes out smooth rather than faceted.
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.
