ᐅ How deep should an edge restraint stone be set in concrete?

Hi,

I want to install a lawn edging stone along a slope as a boundary. On one side, it should slightly protrude, while on the other side, a small path should run flush with the top edge. In other words, there should be a step along the edge. Ideally, the step should be about 20cm (8 inches) high.

The affordable standard stones are usually only 25cm (10 inches) high, but they are also often available in 30 or 40cm (12 or 16 inches) heights.

The question is: how much of the edging stone needs to be concreted or buried on both sides below ground to ensure it stays firmly in place?

I have seen many pictures where edging stones are used as step borders for patios or garden stairs. The steps there typically stand about 15cm (6 inches) high and are visible from the front. Or for flower beds adjacent to lawns, where the beds are at least 10cm (4 inches) higher than the lawn, and one side of the edging stone is clearly visible.

Is there perhaps a rule of thumb stating that one-third or half of the stone needs to be set in concrete to hold firmly? If I were to use a 40cm (16 inches) stone, would a concrete depth of about 20cm (8 inches) be enough?

Thanks and good luck

Kaspatoo schrieb:

Is there maybe a rule of thumb that one-third or half of the brick needs to be embedded to hold securely?

Everyone does it a bit differently, but your one-third guideline works well.

Between one-third and one-half

I agree with the previous commenters. However, it also depends on the intended use. Transitioning from lawn to flower bed is generally unproblematic, while from lawn to step involves a greater load.

Vicky Pedia schrieb:

I agree with the previous writers. However, it also depends on the usage. Lawn to flower bed is uncritical, lawn to step is more of a heavy load.

It’s just a narrow side path, walked on fewer than 10 times a year to do pruning.
Not even wide enough for a wheelbarrow.

I think I will decide on half the size to be on the safe side.

Thank you.

Kaspatoo schrieb:

I think I will settle on half the height to be on the safe side.

I’m known to be quite conservative – to me, it seems rather bold to only dig in half the height when dealing with one-sided earth pressure. Consider the leverage forces and the fact that the edge stone is essentially like an I-beam compared to the L-shaped retaining wall block.

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