Garden Drainage Made Stylish
Garden drainage doesn’t need to look utilitarian. Dan Richards explains more in this blog post.
Behind every thing of beauty lies an awful lot of functional design. Think super-cars, wedding cakes, clothing, shoes and even incredible looking dogs that are the result of generations worth of breeding. Gardens are no exception to this rule. For a garden to be durable and enjoyable, the design of it needs to consider the engineering side of things as well as the aesthetic.
Garden drainage is one of those essential factors that should take precedence when creating outdoor spaces, but it isn’t necessarily something that homeowners want to dominate the aesthetic.
Without garden drainage and careful water management, it’s all too possible for the property to become impacted by damp, for parts of the garden to be unusable at certain times of the year, or even for neighbours to be affected by run-off.
Let’s take a look at some of the techniques that garden designers and landscapers use to manage water on site.
Disguising signs of the household drainage system is all part of landscaping. This recessed manhole cover has been expertly installed so that it’s barely visible. It looks nothing like the old fashioned iron manhole covers!
Hydrological Surveys
A hydrological survey involves inviting a specialist to assess the garden and its surrounding area to calculate how water will behave on the site. Where does it come from? (Eg nearby springs) Where does it go? How does it move around the garden? It’s important to get a good understanding of such things if it seems as though there may be a complex drainage system to design.
Falls On Hard Landscaping Surfaces
In an ideal world, every patio will appear to be nice and level. There’ll be no food rolling across the dining table because it’s on a slope, neither will children’s toys slide around of their own accord. But, a perfectly flat surface doesn’t drain at all well.
When water is ‘allowed’ to sit on a surface it can cause all kinds of mischief. It’s slippery at the best of times, but in winter it can freeze and become extremely dangerous. Then there’s algae. A primitive plant that thrive in damp conditions. It ruin the aesthetic and is slimy and unpleasant.
To avoid hazardous surfaces, we landscapers build an imperceptible fall into each patio, path or driveway we make. This ensures that water doesn’t become a nuisance.
The fall will always be away from the property itself and we’ll be careful to direct the water to somewhere it won’t be a nuisance. For a small patio, we might direct the water on to a flower bed or a lawn. For large areas, the amount of runoff generated could well lead to waterlogged soils, and so we look to install a drainage system.
Does your patio have a slight slope? You can test it by sloshing a bucket of water over the pavers and seeing what happens. Does the liquid flow away from the hard surface? Or does it sit in a sad little puddle until it evaporates away?
Before: Beneath most patios is a drainage system much like this one. When the landscaping is finished all of these pipes will be completely out of sight.
After: A very subtle slot drain collects excess water from the patio and directs it towards a soakaway pit which is buried beneath the lawn.
Aco Drains and Threshold Drains
Sometimes it’s just not possible for all of the runoff from a hard surface to be absorbed by surrounding soft landscaping features. There may also be occasions when we need to build extra drainage into an area. For that we’ll use either threshold drains or Aco drains. These are comprised of a drainage channel sunk just below the level of the pavers and topped with an attractive grill to stop debris falling into them. When they are skilfully installed, these drains are remarkably subtle and don’t detract at all from the look of the area.
Driveway Drainage
Planning regulations deem that if more than ten square metres of a front garden is to be paved (as in a driveway) the surface must either be permeable OR planning permission must be sought.
It goes without saying that most of our clients opt for the permeable paving option. But what does that involve?
Permeable paving is all about creating solid base layers that allows water to percolate through and soak into the ground beneath. Interlocking clay pavers are then laid on top of it and stabilised with a permeable grouting solution.
A great alternative to clay pavers, are those honeycomb grids with a gravel infill. Cost effective, attractive and quick draining.
Soakaway
This soakaway comprises a large empty crate which is carefully wrapped with a one-way membrane so that it doesn’t fill with soil. The pipe leading from the patio drainage system empties into the top of the crate. Water will be seep slowly from the bottom of the crate and percolate through the soil and away into the subsoil beneath.
Directing rainwater runoff onto neighbouring properties is an absolute no-no. It can definitely land you into hot water. So whenever we are recontouring a garden we’ll consider how it will affect the flow of water around the space.
If needs be, we’ll install a drainage system that feeds into a soakaway. A soakaway is basically a large hole in the ground that is either filled with pebbles (we call this a natural soakaway) or is supported by stormwater crates. Either way, excess water is stored in the soakaway until it can be absorbed by the soil beneath it.
Are soakaways visible? No they’re not, they are buried beneath the topsoil. Garden drainage doesn’t need to be obtrusive or ugly.
French Drains for Soggy Lawns
When we’re asked to landscape a site that is maybe low lying or prone to waterlogging, we’ll often consider installing French drains beneath lawns and soft landscaping. These are simply a network of perforated pipes that wick excess water away from the area. Each pipe is encased in a membrane (so it doesn’t fill with silt or get penetrated by roots) and then laid in a deep, gravel-lined trench. This system is often used on bowling greens. Where it contributes to creating the ideal growing conditions for the grass plants. Again, French drains are invisible once they’ve been installed so will not detract from the garden styling.
Weep Holes
It’s easy to think of drainage being an underground thing. But from an engineering point of view, it can also apply to some vertical surfaces. I’m specifically thinking about retaining walls.
A retaining wall generally separates two sections of a garden where one is higher than the other. As you can imagine, building gardens in Somerset often involves changes of level. Depending on the garden design, that means retaining walls are a regular part of my working life.
Every retaining wall holds back an enormous amount of soil. And that’s no mean feat. Soil is heavy! Adding water to soil makes it even heavier. So rather turn a raised terrace into an elevated pool of mud, we build in a drainage mechanism to allow excess water to escape. For large retaining walls, it’s wise to ask a structural engineer to get involved with the design.
Without proper drainage, retaining walls could collapse under the weight of waterlogged soil, or the surface could stain or ‘blow’ leaving a truly horrible aesthetic that is difficult to rectify.
This sturdy stone retaining wall is built on strong foundations and has drainage outlets installed at regular intervals so that water does not accumulate behind it.
Embrace The Conditions
Those who know me, know I’m all about embracing and enhancing nature wherever I can. When it comes to waterlogged gardens, I’m all for turning what seems like a disadvantage into something quite beautiful.
Think rain gardens – where excess water is collected from roofs and hard surfaces and directed towards a pond or a bog garden.
Or how about a wetland garden teeming with beautiful plants and insects and accessed via stylish boardwalks and raised seating areas?
Making Garden Drainage Stylish
Although garden drainage is very much dull subject that conjures up pictures of pipes and valves – it really doesn’t need to look ugly or utilitarian.
A carefully design drainage system is, for the most part, invisible and for the parts that can’t be hidden – there are some very stylish options available.
