Posts & Corners

Sleepers hold the soil across the span. Posts carry that load into the ground, so post size, spacing and pier depth are the numbers that decide whether a wall stands up.

Galvanised steel posts cover almost every job. C channel for the ends and single sided runs, H posts for the spans in between, in 0.4m steps from 0.4m to 3.8m, plus a heavy duty 150 series in lengths to 6.0m for engineered walls. Composite posts are around 90 percent lighter and suit walls up to 1m where everything gets carried in by hand. Corner posts in 45 and 90 degree, with a full steel plate joining the two channels, turn a corner without cutting or fabricating on site.

Which post goes where

• C channel at each end of a run, and anywhere the wall stops against a structure. The open side faces the sleepers, so there is nothing sticking past the end of the wall.
• H post at every position in between, because sleepers land in the channel on both sides.
• Corner post wherever the wall changes direction. Match the angle to the wall line, 90 degree for a square return and 45 degree for a splay.

As a rule of thumb the post is twice the wall height, because the pier depth matches the height of the wall. Size and count yours with the wall calculator, work through C versus H with the guide to choosing steel posts, read the steel post installation guide before you dig, then finish the tops with fixings and caps.