Only Imagination Sets the Limits
When most people think of a decking subframe joist, they picture it exactly where it belongs — hidden beneath a deck, quietly doing its job. And it does that job brilliantly: rot-proof, load-bearing, maintenance-free for 50+ years.
But what if you pointed it in a different direction?
We did exactly that. Using nothing but Ezotrade recycled plastic decking subframe joists, a handful of stainless steel brackets, and a weekend afternoon, we built a large, permanent, rot-proof garden planter — and we think it looks absolutely brilliant.
The Build
The finished planter — three generous bays, solid dark brown recycled plastic, no timber, no rot, no maintenance.
The concept is straightforward. The joists, normally laid horizontal as a subframe, are stacked horizontally here as the walls of the planter. Corner posts hold the structure vertical. Internal dividers — also joist sections — split the run into three separate growing bays.
The result is a planter that looks clean, professional, and substantial. Nothing flimsy. Nothing that's going to bow, rot, or need painting next spring.
Inside the Structure
Open top view before filling with soil — the internal brackets and dividers are visible. Simple, strong, and completely weatherproof.
What makes this work structurally is the same thing that makes our joists good at their primary job: the material doesn't move. No swelling from wet soil, no shrinking in summer heat, no warping over winters. The horizontal boards stay flat and flush. The brackets stay tight.
Compare that to a timber version of the same planter: the boards would start to bow within a season as moisture works its way in from the soil side. Within a few years, you'd be looking at remedial work or full replacement.
With recycled plastic, you build it once.
The Finished Planter
The clean horizontal boarding and corner post detail. Looks like premium timber — performs infinitely better.
The dark brown colour is a standard Ezotrade finish — it sits naturally in a garden environment without looking industrial. No staining required. No annual oiling. Just plant it up and leave it to do its job.
Why Recycled Plastic Joists Work So Well for This
The properties that make our joists ideal for decking subframes happen to be exactly what you want from a garden planter:
100% waterproof. Soil is wet. Compost is wet. It doesn't matter — the material doesn't absorb moisture, so it won't swell, split, or decay from the inside.
Rot-proof and chemically inert. No leaching of preservatives into your soil. Safe for growing vegetables, fruit, and herbs. No concern about what's seeping from the walls into your food.
Structurally rigid. Once it's built, it stays built. The boards won't bow under the lateral pressure of compacted compost. The corners won't rack. The structure remains true year after year.
No maintenance. Ever. No painting, staining, sealing, or replacing. Just plant and grow.
50+ year lifespan. A timber raised bed — even a treated one — has a realistic lifespan of 5 to 10 years in direct soil contact. This planter will still be here in 2076.
What Else Could You Build?
This is exactly the point. The product is a recycled plastic structural section. It's straight, strong, weatherproof, and available in lengths up to 6 metres. What you do with it is limited only by what you want to create:
- Raised vegetable beds at accessible working height
- Herb gardens with separate sections for different varieties
- Composting bays — divides into 2 or 3 sections perfectly
- Retaining walls along a sloped garden
- Cold frames with a polycarbonate lid on top
- Sandpit surrounds for children's play areas
- Log stores with slatted sides
- Tree surrounds and planting collars in paved areas
- Pond edging and water feature surrounds
If you can sketch it, you can build it. The material does the heavy lifting.
Ready to Build Your Own?
Our decking subframe joists are available in solid and hollow profiles, in brown, grey, and black. They can be cut to length on site with a standard wood saw and drilled with standard tools.
Tell us what you want to build — we can help you work out the quantities, profile sizes, and fixings you'll need.
Request a quote for decking subframe joists
Browse our full range of recycled plastic profiles
Built once. Built sustainably. Built to last. — Ezotrade Ltd