Why We Chose Corten Steel Over Sleepers for This Sustainable Harpenden Garden
Corten steel retaining wall replacing old wooden sleepers in Harpenden garden
A Sustainable Vision for a Harpenden Garden
In the heart of Harpenden, we were approached by homeowners who both work professionally in the field of sustainability. Their brief was clear: replace a rotting timber sleeper retaining wall with a solution that aligned with their eco-conscious values — not just in aesthetics, but in long-term impact.
This wasn’t just about good design. It was about making a decision that reflected their life’s work.
Why the Sleepers Had to Go
Timber sleepers have long been used for garden edging and retaining structures, but as with many materials, time takes its toll.
“In my experience, even well-treated timber sleepers begin to show significant degradation after around 7 years.”
While some reclaimed or sustainably-sourced timber options exist, the idea of continually replacing sections every decade felt less like stewardship and more like a cycle of waste — especially for this couple.
The Case for Corten Steel
When we introduced Corten steel as an option, it immediately ticked the right boxes.
✅ Longevity Meets Low Maintenance
A 3mm-thick Corten planter loses only 1mm over 40 years of weathering.
The 6mm steel we specified? It could last well over 100 years in a garden setting.
Virtually no maintenance required — no staining, sealing, or replacing.
✅ Recyclability and Reuse
100% recyclable — it can be reshaped or repurposed in future redesigns.
No waste to landfill at the end of its life.
✅ Kind to the Soil
Unlike some treated woods or composite materials, Corten has a neutral pH and doesn’t leach chemicals into the soil. It’s safe to use near edible gardens, trees, and wildlife habitats.
✅ Minimalist Beauty
The warm, natural patina of weathered steel complements both modern and traditional garden designs — blending beautifully with natural planting palettes.
“This wasn’t just about replacing sleepers — it was about upgrading the garden to match the homeowners’ values and lifestyle for decades to come.”
What About Sustainable Timber?
It’s important to acknowledge that sustainably harvested wood does have a place in garden design.
We often work with suppliers like Huws Gray, who hold both FSC® and PEFC Chain of Custody certifications, ensuring timber is harvested with care and reforestation programmes are in place.
But the question remains: Is harvesting aged trees — even responsibly — to create a product with a 7-10 year lifespan really sustainable?
Design Outcome: Durable, Beautiful, and Aligned
The result? A visually striking, architecturally clean retaining edge that complements the planting and brings a timeless elegance to the garden — one that will likely outlast the house itself.
“We weren’t just redesigning the garden. We were making a statement about how design and sustainability can — and should — go hand in hand.”
Thinking about updating your garden sustainably?
Let’s design something built to last.
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