What to Expect During a Retaining Wall Build

Retaining work is heavier and messier than most residential trades, and knowing the shape of it in advance removes most of the surprises.

Before anything starts

Set-out and services come first. Anybody excavating needs to know where underground services run, and on a residential block that means a services search and usually locating on site. Hitting a service is expensive, dangerous and entirely avoidable.

The boundary gets established if the wall is anywhere near one, and that means the actual surveyed boundary rather than the fence line.

Access is planned. Where the machine comes in, what it drives over, where the spoil is stockpiled and where materials are set down. Protecting driveways, paving and irrigation on the access route is part of this and it is worth agreeing before the first machine arrives.

Excavation, and the noise

The bank is cut back to give room to build, and footing holes are dug or bored. This is the loud, dusty and visually alarming part: the yard will look considerably worse than it did before anything constructive is visible.

Expect a machine on site, expect the ground to be disturbed well beyond the wall line, and expect the spoil pile to be larger than the hole appears to justify, because excavated material bulks up.

If rock or unexpected ground is found, this is when it comes up. It is also when anything about the ground that changes the footing design becomes apparent, so if there is going to be a variation this is usually where it originates.

Footings, and the wait

Footings are poured and then they cure. Concrete needs time before load can go on it, and building a wall onto a footing that has not reached strength is a real failure mode rather than a technicality.

That produces days where nothing visible is happening on your property. It is not neglect and it cannot be shortened by adding people.

The wall

Posts set, sleepers or blocks placed, courses built up. This is the fast part and the part that looks like progress. On a block wall, add the reinforcement and the core fill, and another cure.

The part that matters and takes longer than you expect

Drainage and backfill. The subsoil drain goes in at the base, the free-draining aggregate goes behind the wall, the filter fabric wraps it, and the outlet is connected to somewhere real.

Then backfilling in layers with compaction between them, rather than pushing the whole lot in at once. Uncompacted backfill settles over the following year and everything built on top of it drops with it.

This stage often takes as long as building the wall did and produces almost nothing you can see, which is precisely why it is the stage that gets rushed on cheap jobs.

Reinstatement, and afterwards

Spoil removed, the access route made good, the area tidied. What the finished surface behind the wall looks like depends on what was agreed: topsoil, turf, paving and planting are usually separate.

Expect some settlement in the first year even with good compaction, particularly after the first serious wet. Minor topping up of levels behind a new wall is normal. Movement in the wall itself is not.

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