Published: January, 2021
With so many different options to choose, how do you pick what is the right metal edging for your garden project?
Steel and aluminium, lawn and landscape edgings have come a long way since the days when timber, concrete and even terracotta, were the garden edgings of choice. Having the right material, the correct height and even the right choice of fixing can make a huge difference to the result.
So, to keep this simple, there are certain critical points to think about, starting with the appearance of the finished result - how much can you see of it in the finished project, and then how much and what type of traffic will the edging be subject to?
To allow for these two important points, you then have five main elements to consider, these being:
The first thing to consider is Height, it is well to note that the difference between 100mm high and 150mm may seem disproportionate so you will need to consider your budget carefully here. 150mm high edging is excellent, but do you need it?
Only if one of the surfaces will be walked across, is near to vehicle traffic, or you require a difference between one height and another, should you need anything more than 100 mm. In some situations, you can quite easily use 75mm successfully for lawn edging but the small additional cost of 100mm, will be worthwhile in terms of durability and ease of use when installing it. There should be a minimum of one third in the ground both sides when installing with a differentiation in height.
The required Finish will be one reason you may choose one material over another, but this is simply aesthetic, so whilst important, it is not a technical decision and should be considered dependant on the other elements within the decision-making process.
Choice of material determines both what it looks like, and how it performs so this is probably the next question to ask yourself. The popularity of weathering (corten) steel is due to its long-lasting properties and natural appearance, so it is a great choice. However, many ‘corten’ steel products available now are not made of a material with weathering properties so corrosion could be a problem if you are buying ‘natural’ unfinished mild steel. Be aware, as proper weathering steel is significantly more expensive, for good reason!
A great alternative to steel is aluminium which although not having the natural looks of proper Cor-Ten® or unfinished mild steel, is light, and very resilient to the elements, especially when in damp conditions for long periods, which could quickly corrode mild steel.
Aluminium is usually a little more expensive for the equivalent thickness but is extremely strong. One thing to be aware of when using aluminium is its tendency to kink once bent into a curve whereas steel is springier so will flex back into a straight line. For this reason, particular care should be taken when looking to curve aluminium as you will be unlikely to make it straight again!
If you are looking for a flexible metal edging, then both steel and aluminium have properties which will lend themselves to following the gentle curve of a path or lawn edging against a flower or shrub border.
The thickness of material depends on whether you go for aluminium or steel. The best aluminium edgings are all extruded, which makes it much stronger than a thin sheet, folded in an L shape, and the thickness of extrusion as designed for maximum strength will generally have a top edge of around 5.0mm.
Steel landscape edgings start from 1.6mm and go up to around 8.0mm for heavy-duty applications. However, for a lawn to border application, something around 3.0mm is probably the best thickness you should aim for, although you may find an aluminium equivalent, due to the extruded profile, has a 5.0 mm top edge and actually handles and fits more easily. At the minimum point, an aluminium edging should be no thinner than 2.0 mm thick.
A key element to consider when thinking about the thickness is the longevity of the product and although a thinner material if fine when installed, if it is steel it will eventually rust away leaving a very sharp top edge as it does so. Aluminium or 5.0 to 6.0 mm steel, will last much longer and be safer – something not previously mentioned in this content.
So, if you are considering a timber lawn edging or concrete path edging, consider metal edging instead as it is competitive in use, faster to install and won’t rot or chip in the same way. It is also more flexible and will follow those sinewy curves, giving an exceptionally neat and clean edge.