A wall can be used to create usable space on a sloping block or to create visual interest in an otherwise flat garden. Regardless of whether it’s designed for practical or aesthetic purposes, it needs to be designed and constructed well in order to serve both. One such area that requires careful consideration is waterproofing. Here are the top 10 tips as shared by retaining wall builders:
The purpose of these walls is to hold off soil when there’s a drastic change in elevation. If they’re under a metre high, they should be well within the scope of a DIY project. If they’re higher than this, however, then you should seek professional advice before proceeding.
Poorly built walls can bulge, crack or lean and become an eyesore. In more serious cases, they’re even known to topple over. This is why many councils like to see your plans before you begin work. If building close to the boundary line, you may also have to speak with your neighbours.
- 3.Pipes & Cables
Be sure to check your plans against any plumbing and electrical diagrams to ensure that you don’t have any nasty surprises when you start digging. If you don’t have access to these diagrams, you should call a local dial-before-you-dig service to see what they think.
A well-designed wall won’t tip over and will support the soil behind it (as well as any loads that may be applied, such as cars). It will also prevent water buildup (which increases the lateral load). Gravity walls rely on their mass, whilst cantilever walls are stabilised by their footings.
- 5.Solid Base
A solid base starts below ground level. It consists of compacted soil and at least 150mm of compacted sand and gravel. The compacted base ensures that everything remains flat. More contact also increases friction, which means that you end up with a stronger construction.
- 6.Good Beginnings
Generally, the higher the wall the deeper below ground it begins. A good rule of thumb is to have one tenth of the height below ground level (ie a 90mm high wall should have at least a 90mm base below ground). Also remember to dig back 300mm for gravel backfill.
- 7.“Use the Force”
Retaining wall builders understand how to use gravity to their advantage by stepping the wall back towards the soil. This will perform the dual function of providing the wall with stability, as all of the components rely on each other in order to stand tall.
Effective drainage is critical. Without it, pressure will build up behind the wall and create bulging or cracking. Three effective ways to ensure good drainage include gravel backfill, the installation of perforated pipe (with drainage cloth), and providing weep holes for water to drain.
These walls might look as if they have to hold back tonnes and tonnes of earth, but they really only have to hold back a small wedge. Rather than filling the wedge with moisture-loving soil, fill it with sandy gravelly materials that compact easily and allow water to drain.
Retaining wall builders know that providing adequate drainage isn’t enough – you also need to provide waterproofing treatments. Apply a waterproofing membrane during construction – this will help to avoid a host of problems and protect any systems.