sleeper retaining wall
 

It seems like retaining walls are a big subject but sleeper retaining walls?

We were considering a drystack or versalok type of retaining wall but the materials cost alone is a lot! Plus hauling all that rock, ouch. So we're leaning towards a wood retaining wall now because of cost and ease of installation.

I see a lot of information on installing the "typical" wood retaining wall of horizontally stacked 4x4's or 5x6's, laid down on top of a tamped 12" base of gravel, with some drain tile behind it and all that. But I was curious about why there is so little information on sleeper retaining walls? (they seem to be the choice wall for aussies, at least). They also look a lot easier to install (few posts, some boards, no foundation worries).

Any reason (besides being wood), that anyone wouldn't use a sleeper style retaining wall?