Installing the Garden Edging
To edge between the deck and the garden bed I had decided to set permapine sleepers into the ground. We had decided to do the same thing between the sandpit and the lawn. I've used this method of edging before and like it because it's durable, quick to lay, and provides an easy straight edge against which to mow the lawn. We had considered it to edge between the lawn and the garden bed but decided to use pavers set in mortar to achieve a curved profile that looked a lot better than a straight line.
Setting the Level
Critical for the edging along the side of the deck was the level. I had intended that the edging would protrude enough to cover most the ends of the deck bearers and stop stray balls or other things from getting under the deck. However, it needs to be low enough that the deck surface can run over the top of it as I intend that it can be largely covered. My deck surface is determined by the bottom of the door on the garden shed. The door needs to be able to open, and to allow for any movement I decided to allow 20mm between the bottom of the door and the deck surface.
I put a peg in the ground next to the door and marked the deck height on it less 22mm (22mm is the thickness of the decking material I will be using). I ran a string line from this peg across the area where the edging was a pegged the other end. Pulling the line taut I used a string level to level the whole thing out. It was then simply a matter of excavating a trench for the sleepers and ensuring the depth of the trench was at least the height of the sleepers below this. I decided on 250mm. Excavating the trench I made use of a trenching shovel, it's narrow spooned head made cleaning out the trench a lot easier. I also made use of a length of 2m wood to place in the bottom of the trench from time to time to test the level of the trench.
Installing the Edging
The sleepers would be layed on their edge in the trench and soil backfilled around them for stability. To provide extra strength I used a long auger bit on my power drill to drill a 10mm hole through the sleepers. Through this hole I hammered 600mm lengths of 10mm steel concrete re-inforcing rod. I used three lengths for each length of sleeper I installed. Also where the cut ends of the sleepers met I skew nailed 4 nails from each side to produce a stronger joint. At all times I checked the level of the sleepers (both horizontal and vertical) and gauged their position against string lines. This helped to ensure correct installation.
How Much Did I Get Done?
I got all the edging done in 2.5 hours. This consisted of a 2.4m sleeper, and three sleepers cut to length at 1.5m, 2.2m, and 1.75m. Of this I would guess that digging the trench took around 2 hours. Next time I'll soak the area the night before with the garden sprinkler to make digging a lot easier. The hot dry weather we've been having meant that I needed to use the pick along the whole length to break up the hard clay.