Curved oak sleeper retaining wall in Brighton and Hove

The job

This garden in Brighton and Hove had a change in level, with the surrounding properties sitting higher. The customers wanted to make better use of the space and find an attractive way to deal with the raised ground. They also wanted two separate areas: somewhere for their children to play and a space for their dogs. They liked the look of upright timber sleepers and wanted them to be part of the design.

What we did

We agreed that upright oak sleepers would give the customers the look they wanted while holding back the raised ground. The main question was how to secure them properly, as the wall followed a curve and was retaining soil. We excavated a trench approximately 400mm deep along the line of the wall, then set treated oak sleepers vertically in it and secured them with concrete, adjusting each one to form the curve. The sleepers had been burnt to give them a darker, more distinctive appearance. They were joined with landscaping screws, with metal strips fixed behind them for extra strength, and connected to piles installed in the bank behind for additional anchoring. A protective membrane and a shingle drainage layer went in behind the sleepers to protect the timber and let water drain away. Once the retaining wall was complete, we prepared the children's play area with approximately 150mm of compacted Type 1 sub-base and a layer of crushed granite dust, ready for the rubber safety surface.

Challenges

The biggest challenge was building a curved wall while keeping every upright sleeper securely connected. Unlike a straight wall, each sleeper had to be positioned carefully to hold a consistent shape. We also had to prevent movement over time under the weight of the soil behind the wall. The answer was to combine the concrete foundations, the connections between the sleepers and the extra anchors into the bank.

The result

The finished retaining wall gives the garden an attractive way to deal with the change in levels, with the curved upright sleepers as a distinctive feature. The garden now has separate areas for the children and the dogs, and the play area was left ready for its rubber safety surface. The project took three weeks. It is a good example of how much thought and preparation can go into something that looks relatively simple once it is finished.