Hi,
We're planning to replace our sloped concrete in our back patio with a retaining wall. We're looking to do it using concrete sleepers as we're under the impression that we can attach the existing timber patio posts to the tops of metal C/H section posts using the same brackets as you would with timber fence posts.
The height of the wall will be 0.6m
The height of the timber patio posts will be 1.6m, from the top of the wall
The wall will be 1.6m from the pool
My question is, do typical retaining wall instructions apply? (For example, are 1.2m C/H posts going to be long enough?) Or is this something we would need to consult someone qualified on?

