BUILD A STONE RETAINING WALL THAT WILL LAST

 

Low to mid-height stone retaining walls are an attractive way to edge a driveway, lawn, vegetable patch, or even just create some structured spaces or ‘rooms’ within your garden. The ‘dry stack’ construction technique is popular amongst homeowners looking to do the work themselves. It’s a relatively straightforward method, provided the planned structure isn’t over a metre high if it’s going to be freestanding, or slightly higher if it has a slope or bank providing support from behind.

Another great virtue of these retaining walls is that they’re mortarless, and therefore come with a ready made drainage system as water just seeps through the cracks in between the stones. This not only helps your garden’s natural drainage but it also means the pressure of water behind the wall is hardly ever big enough to cause substantial damage, even in torrential rains.

So if you’ve got big ambitions for your garden, why not forego the gym this weekend and set about creating an interesting stone feature instead? You should be able to complete a three by one metre wall in about two days of fairly solid work.

1. Get prepared and tooled up

Before you begin, check that you don’t need any kind of permission to start digging in the area where you plan to build your wall. This is unlikely to be the case with such a small structure, but it’s always worth considering. Also make sure that there aren’t any buried pipes or cables nearby.

It’s important to work out the quantity of stone and other materials you’ll need by measuring the length, width, and height of the structure to be built. Try to do this with someone who can help hold the tape measure and write down calculations. Don’t be afraid to repeat this several times until you’re certain you have accurate dimensions. There’s nothing more frustrating than getting towards the end of a job and realising you’re about to run out materials – it’s the worst! Some people find it helpful to use a garden hose to ‘try out’ various lines, shapes, and lengths before they commit themselves.

Search online for a good stone and granite supplier (hint: you’re already looking at one!), or visit a showroom in person. You might want to go for ‘stackable’ stones, those that have at least two ‘flat’ sides at the top and bottom of each layer, as these will be easier to work with. Heavier stones make for harder graft but will give greater stability in the long run. You will also need gravel and premixed cement, unless you mix it yourself, for the foundations. To minimise lifting, try to have the materials delivered as close as possible to the project site.

In terms of tools, make sure you have:

  • Tape measure
  • Long length of string
  • Spirit level
  • Rake
  • Stone hammer
  • Two stakes
  • Shovel
  • Hose
  • Wheelbarrow
  • Tough gloves
  • Tamper

2. Measurements and levels

First, establish where the ‘face’ of the wall will be by hammering two vertical wooden stakes into the ground just in front of the proposed structure, at either end of the length you have planned. Fix a piece of string tightly between the stakes about 20.5 centimetres from ground level, and check that it’s level with a spirit level.

Using a tape measure, determine the number of ‘steps’ or slabs of stone you’ll need between the top point of the completed structure and the ground. If you’ve gone for easy-to-work-with large blocks, each slab will be approximately 15.24 centimetres in depth. So if you’re aiming for the total height of the wall to be, for example, 61 centimetres, it will require four steps of stone.

3. Firm foundations

Dig out the ‘footing’ for the first step to a depth of at least 15 and a half centimetres, forming a trench all along the line of the soon-to-be-wall. Its width should be one and a half times the size of the largest block you plan to use.

Pour concrete into the channel you’ve created. Pack this down and smooth with a hoe or the back of a metal rake. Continue the process until you have formed a flat, solid surface that finishes just below ground level.

4. Let the building commence

From the bottom horizontal stone layer or course, choose large, square or rectangular pieces to give a solid base. Carefully place the first stones onto the concrete footer so that their front lies flush with the proposed face of the wall. If you angle them slightly forward, it will allow the rain to run off easier.

As you build, continue to backfill any gaps behind the wall with rubble or scree.

Now adjust your stringline to the height of the second stone layer, ensuring it’s still straight with a spirit level. Place another row of stones on top of the first, taking care that the joints are staggered and angled slightly backwards. Do not move on until each stone placed feels firm and stable. Plug any slight gaps between the large blocks with small stones.

You may need to shape some of the stones or granite pieces to suit. The best way to do this is by first marking a line across the width of the stone and then drilling five centimetre holes every seven or so centimetres along the ‘cutting’ line. Insert small wedges into these holes and shit with a stone hammer until the block splits as required.

Continue adding courses until you have almost reached the height required.

Choose the stones for the top layer extremely carefully so that they fit together snugly to give a pleasant, smooth finish. If you want a more secure top, fix the cap stones into a bed of premixed mortar laid on the penultimate course of the wall.

Finally, backfill behind the structure up to the level of the capstones with gravel or any other materials that suit the landscape in which it sits.

5. Make yourself a cup of coffee, stand back, and admire your handiwork

If you’ve followed our instructions carefully then this is something you’ll be able to enjoy looking at everyday for at least the next ten years! Good job!