Stacked sandstone is great for building a low-level retaining wall. Not only will it add natural beauty to the landscape, but, if built correctly, it will last for decades. Constructing a sturdy wall is similar to playing a 3D game of Tetris, except you get to cut and shape blocks to make them fit. However, if you’re going to be using large blocks (like we did), it’s a good idea to hire a mini excavator and a skilled driver to help move and position them – the blocks can weigh more than 400kg!
Gather your supplies
• Loose sandstone or local stone
• Mini excavator and driver
You’ll also need
Lump hammer; bolster; scutch hammer; stringline; timber pegs; tape measure; spirit level; goggles; shovel; wheelbarrow; large sponge; bucket; brickie’s trowel; garden soil mix; mulch
1. Work with your mini excavator driver to direct placement of the stones.
2. A 1.5t mini excavator can lift a maximum weight of 400kg!
Step 1 Remove existing wall with help of driver (if necessary). Clean out rubble, remove plants and major plant roots (if any). Ensure ground is well compacted.
Hammer in a peg at both ends of retaining wall, so stringline extends at least 2m beyond retaining wall.Run stringline between pegs to mark front of wall and height of base.
Step 2 Spread out stones and select suitable sized blocks for each section. For base, choose large, square-shaped stones. Advise driver to lay blocks along wall, taking care to avoid stringline, or freeing where needed. Check course is roughly level and adjust if needed.
Step 3 Fill in gaps behind wall with small rocks.
Step 4 Adjust stringline to height of second course. With the help of a mini excavator, position second course, ensuring joints are staggered on face of wall with a slight backwards rake or slope.
Check to make sure course is roughly level. For a visual contrast, try positioning large feature stones vertically. Shape stones to fit, if necessary
Step 5 Continue adding additional courses until wall reaches approximately 600mm high. If wall is on a slope, use large blocks in place of laying courses, ensuring they are roughly in line (horizontally) with rest of wall.
Step 6 For stones that won’t sit flat, position offcuts or stone wedges behind or underneath blocks to chock and hold them in position.
Step 7 To secure capping and prevent rocking, fix to top of wall with mortar. To do this, mix 4 parts sand with 1 part cement, then gradually add water until mixture becomes stiff. Using a large sponge, wet back of capping stones and stones.
Step 8 For an eye-catching finish, fill up back of wall with a mixture of plants, backfilling holes with garden soil mix as you go. Mulch and water well.