I am not sure this is a factual question or not, but GQ won the coin toss…
We are looking to put a dry stacked slate wall in our yard to separate our grass from flower beds. I imagine total height would be about 5" high and about 8" in width. No mortar. The flower beds may be 2 inches or so higher than the yard due to added mulch.
What I am not sure of is does it needs some kind of special base?
I have looked online and most places mention digging a trench and using aggregate, etc. But they are also building much larger walls that are holding back substantial amounts of dirt.
Do I need to do this? Is there something I am missing?
I have a hard time calling anything 5 inches tall a wall. I guess it’s more of a flower bed border than a wall? If so then you don’t need to do anything fancy to it. If you are placing the slate on top of loose topsoil from the garden beds then the slate will settle and will become uneven. If you tamp down the soil where you want to place the slate then you shouldn’t have a problem.
We have a flower garden around our tree in the back yard and it has a stacked stone border (not slate, but it’s the same idea). We’ve had it for years and haven’t had any issues with it other than rain runoff from the house causing erosion in the yard and making the stone uneven. But that’s a problem with the design of my gutters in general and has nothing to do with the stone border.
I did something like that, I think it’s 3 courses high and my first thought was to just drop them in, right on the (tamped) dirt and if they heave, whatever, I’ll just pull them out and reset them next year. It’s only about 10 feet across. But, as I started working the base to get it level, I figured I might as well get the sand down there and actually make do the base correctly. Then I dry stacked all the bricks and, again, figured that after all that work I might as well glue them, so I pulled them and glued them with Liquid Nails (or something similar). It’s been a few years now and the thing is still perfectly level. You can walk on it, stand on it, sit on it, it’s not going anywhere.
If I half-assed it, I’d be rebuilding it, hammering bricks back down, telling people they can’t stand/walk/sit on it because it’ll move.
Do it right, do it once. Just putting down the correct base isn’t going to take that much more time, especially for something so small. Here’s all mine is, maybe a bit bigger than yours, but it’s still hardly a retaining wall, but that’s how I built it.