Retaining Walls in Cashmere, Christchurch

Cashmere sits on loess, the wind blown clayey silt that covers the developed Port Hills over volcanic rock. It is the single most important thing to understand about building here. Undisturbed dry loess stands at a near vertical face with high apparent cohesion, which is exactly what convinces people the ground is stable. Wet, it behaves very differently.

Why loess catches out Cashmere retaining walls

You can cut a face in dry loess and it will stand there looking solid for weeks. That is apparent cohesion, and it disappears once water gets into the soil. For residential wall design on the Port Hills, drained parameters of zero cohesion and a thirty degree friction angle are commonly assumed, which is a far less generous picture than the face suggests.

It is why drainage on a Cashmere wall is not an optional extra and why we water test and excavate behind an existing wall before quoting a repair.

Terraced retaining walls are the Cashmere job

Long slopes with houses set well back from the street mean most sections here have a bank that is doing nothing. Stepping it into two or three levels turns dead ground into lawn and planting, and it is what we are asked for most often in this suburb.

The catch is the consent rule. Terraced walls close together are assessed as one combined structure, because each upper wall surcharges the one below. Three tidy 1.2 metre walls do not produce three exempt walls, and we check the geometry before quoting rather than after.

Access on a Cashmere section, and what it does to retaining wall cost

Cashmere sections are long and many of them climb. When every post, every bag of concrete and every cubic metre of drainage metal goes up by barrow rather than off a truck, that is real labour and it belongs in the quote.

We assess access at the site visit. A wall here can price meaningfully above the same wall on a flat Halswell section, and knowing that up front is better than finding out on day two.

Retaining wall jobs we get called out for in Cashmere

• Retaining Wall Builders in Cashmere, free site visit and a fixed written quote.
• Retaining Wall Repair in Cashmere, we find out why it moved before quoting anything.
• Timber Retaining Walls in Cashmere, h5 treated posts set in concrete, H4 sleepers.
• Concrete Block Walls in Cashmere, reinforced and grout filled on a designed footing.
• Poured Concrete Walls in Cashmere, monolithic cantilever walls on an engineered footing.

Cashmere sits on the same run as Westmorland, Huntsbury and St Martins, so we are usually in the area anyway.