Gabions

A wire basket filled with quarry waste stone - a simple but highly-effective idea

Hold up your bank with a gabion!

Gabions are a cheap and relatively easy way of stabilising an excavation or retaining a bank of earth. There are two basic types - Gabions and its flatter sibling, the Reno Mattress.

A gabion is a wire cage which is filled with large stone - what would once have been quarry waste (and hence cheap to buy). With the increase in popularity of these cages and also the demand for garden rockeries (the two main uses of extra large blocks of rock), the price has gone up and we had to pay €17 a tonne just for the stone (not including delivery). Not so many years ago these same blocks would have been free to collect with the quarry just being glad to be rid of its rubbish. Fortunately we did not have to buy too many tonnes since our garden is full of the same large blocks which we had thoughtfully set aside during the excavation works.

Our drive consists of three sections - the end near the house, a long, straight section which is ours exclusively and a winding shared section which could belong to us, our neighbours or both of us depending upon how you view a drawing which is out of date and (of necessity) incorrect since the recent earthquake. Because of hunters and our house being at the end of the road, we get casual traffic turning around right outside our house thus denying us the privacy we desired when purchasing the house.

The idea was to cut back the bank at the end of our section of the drive and widen it on both sides. This involved considerable excavation on one side and fill on the other as the drive cuts into the side of a hill at this point. At its deepest, there is a 3 metre face of soil exposed - obviously too much to be safely left unsupported. The alternatives were to build a wall in block, stone or concrete or to opt for gabions which are commonly used in this area.

Despite their prevalence, our contractor found it hard to locate the bigger size cages that we wanted and we had to ring around the various heavy builders merchants to locate some. In the end we had a dozen or so 2 metres x 2 metres x 1 metre gabions along with some smaller ones that he had bought elsewhere.

We stacked the first row along the bottom of the excavation and then began filling the baskets with stone. It is possible to just use a digger bucket to place the stone but it makes a neater job if it is placed by hand - much like a quick form of dry stone wall.

As soon as a cage is filled the wire lid is lowered and wired tight. When the adjacent cage is filled it is wired to the previous one and, in this way, the wall is assembled to function both flexibly and as a single piece. When a row is complete, a new layer of cages were laid on top but staggered (like bricks laid in stretcher bond).

When we'd finished with the gabions, we dug a shallow trench along the face at the bottom and planted some roses, wisteria and other climbing plants. Hopefully, in a few years, the wire will be virtually invisible and the whole wall will look very 'rustic' and natural.

The great thing about this type of retaining wall is there is no problem with hydrostatic build up (ie trapped water) behind the wall, it is virtually maintenance free and it blends in very quickly unlike a brick or (worse) concrete wall which will forever remain an eyesore. Italy is keen on this type of soil retention and we were happy to 'go with the flow' and do likewise. On top of that, the bottom line price is usually lower than for other construction methods.

At the time of writing our plants are just beginning to take but give it a year or two and they should be very well established.

Click here to see what a Reno Mattress is.

If you're passing, why not come and see our gabions?