Sloping gradients on a garden will show themselves as a challenge when attempting to maintain or build upon the space. Flat lawns are impossible to achieve with sloping gradients. Heavy rain will wash away garden borders, and path ways become inconvenient without stopping to think about the placement. One of the original and most impactful solutions are timber sleepers. These will create levels to what would otherwise be a continuous battle with earth and gravity.
Why Slopes Create Problems
Sloping soil does not move in an extreme fashion, but it does move. It will wash soil down the slope with rain, compact soil unevenly with foot traffic, or by its own weight move the soil over time. This will undermine a garden. Without management, there might be flooding in the garden due to lack of drainage or an upper garden bed will not have the nutrients required to sustain healthy plant life. Terracing arrangements of soil create levels to manage soil movement.
How Sleepers Help
These are perfectly adapted to solve these soil movement issues. They can be stacked to form walls that hold soil in place and provide structure to the garden. These can create lawns, garden beds, and pathways and are probably the best solution for this problem due to their weathering ability, aesthetic look compared to gravel and brick, and their simplicity to install.
Choosing the Right Type
Sleepers are not the same and being on a slope as opposed to a flat surface means that the choice is even more important due to the different amounts of load.
– New softwood are the cheapest and most accessible option, but treatment is necessary due to contact with wet soil.
– Hardwood are more expensive, but last much longer, resist better, and are much more effective for supporting and holding back several tonnes of wet soil.
– Reclaimed railway look nice, but older sleepers are treated with creosote, which is harmful and a risk if you are placing the sleeper in a vegetable garden or a play area for kids.
– There are also concrete ones which look like timber but are a more modern option and as such require no maintenance unlike the timber do.
Getting the Structure Right
Building a retaining wall from sleepers requires more consideration than simply stacking timber. A wall above 600mm requires a proper foundation and drainage to relieve the load of water. To aid the pressure, the wall can be backfilled with gravel to encourage drainage. In addition, soil can be held in place with timber posts or steel pins.
Think in terms of levels rather than a single long slope. Two or three walls with a gradual slope each are less stressful to a structure than a single tall wall. It may also look better to segment a garden with several walls into usable sections rather than having a single long slope.
Beyond Function
Design also plays a part. Different levels of a garden create different opportunities for planting/gardening or even just relaxing. Sleepers can be walls or stairs between garden levels and can serve the garden in several ways just by being there.
A Few Functionalities
Building a retaining wall within the height limits and property limits can yield a good garden. However, check your local property limits and set a height limit of 1 metre for retaining walls (or anything similar) before you begin building anything. Retaining walls require a commitment to a garden, and your soil should be a factor of your commitment. Clay and Sandy soils behave very differently, but with retaining walls the pressure is the same.
In the end, if you do it right, retaining walls can segment a garden into purpose and utility rather than having to traverse the garden in an obstacle course. It takes commitment to get right and is not a weekend project, but makes a garden usable rather than a space you tolerate.