What Lies Beneath

By November 8, 2013 November 13th, 2013 Blog, Professional Articles


In a landscape project, it is what lies beneath that is crucial yet is often where much of the cost and time is spent. It is also what separates a good landscaper from a bad landscaper and it is often well after the garden is completed when inferior foundations are revealed.

What lies beneath the surface is the hidden but necessary cost; you can’t see where the money and time has been spent post completion but money not spent here will end up costing you more in the long term. These areas include: drainage, the paving base and paving adhesive, retaining wall foot-ings, soil quality and preparation.

Drainage presents as one of the biggest issues for failing landscapes and most often the source of complaints from clients. If appropriate drainage systems have not been installed under paving, around retaining walls and swimming pools, the end result will include cracked and shifting pavers, water run-off in the wrong direction (usually towards the house and not away), structural problems with retaining walls and plant failure. Expenditure and skill during the initial construction phase is necessary. This stage is not shown in lifestyle garden shows and it can consume the bulk of the construction period, as well as absorb much of the budget because it is often labour intensive. It is a necessary evil so to speak, so don’t skimp on the budget here and make sure you seek out a professional who knows what they are doing.

Retaining walls must have footings to combat the weight of the material that they are supporting. The higher the retaining wall, the more substantial the footings should be. Drainage should be set lower than the footings to ensure that water is drawn away from the footings that give the wall its structural integrity. For retaining walls over one metre, a building permit is required to check the engineering of the footings; a failed retaining wall is more than just unsightly, it can also be very dangerous.

Getting the base right to paving projects is also the key to a successful paving project. Imagine installing a rigid structure such as a concrete base on ground that naturally moves due to soil and climate conditions; if no provision for movement has been made then the paving will crack at its weakest point and the pavers will shift, lift or crack. You won’t discover this until months after the project is finished. The base needs to be strong enough to sustain small movement, usually achieved through the thickness of the slab and use of steel reinforcements, and expansion joints, cut through both the paving and the slab, to accommodate the expansion and constriction of concrete. Some may view expansion joints as unsightly but they do serve an important function and should not be excluded purely for aesthetic reasons. A good designer will factor the location of expansion joints into the paving design to minimise aesthetic concerns.


The slab and paving should also be laid to slope towards where the water needs to go, either towards a stormwater drainage collection point or the garden. But be aware that in choosing the latter, significant rain will increase the water to garden beds that are already saturated and may result in plant deaths, further exacerbated if your soil has high clay content. For large areas of paving, drainage is the only solution.

And finally I mentioned soil, which lies beneath the plants. Your soil type will play a significant role in ongoing health of your plants. Clay soil retains water, sandy soil drains water away. Drought tolerant plants don’t like soggy feet and so on. Time and energy spent in aerating the soil and if necessary enriching it with compost prior to planting, will ensure the plants get the best start. Loose soil will allow for root establishment and drainage. A landscape designer will undertake a soil analysis as part of the preparation of the design; this allows them to recommend plants which are best suited to the soil and environment.

A landscape builder will properly prepare the site and may recommend soil additives to improve what’s there trust their judgement. If after all of this your budget does not quite stretch then reduce the size and quantity of the plants because now that the foundations have been taken care of your plants will thrive and grow. Just like children as my grandmother would say.


julie edmonds

Executive Officer, Landscaping Victoria

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