Dincel Retaining Wall Engineering

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What Is a Dincel Retaining Wall?

Dincel is a permanent PVC plastic formwork system that stays in place after being filled with reinforced concrete. Unlike traditional formwork that gets stripped after the pour, Dincel panels remain as part of the finished wall, providing a waterproof, durable outer skin that protects the concrete and reinforcement inside.

The system uses snap-lock panels (manufactured in Sydney by Dincel Construction System) available in 110mm, 155mm, 200mm, and 275mm wall thicknesses. For retaining wall applications, the 200mm and 275mm profiles are most common. Panels connect via a patented snap joint — no bolts, ties, or clamps required.

Dincel retaining walls are essentially reinforced concrete walls with a permanent waterproof skin. They carry the same structural capacity as conventional reinforced concrete but with built-in waterproofing (backed by a 50-year leak warranty) and significantly faster construction — two people can install 25m² of formwork per hour.

Engineering Design Considerations

Wall thickness selection — 200mm profile handles most residential retaining applications up to approximately 2.0–2.5m retained height. The 275mm profile is used for taller walls, higher surcharge loads, or where additional reinforcement is needed. The wall thickness determines the available space for reinforcement and concrete cover.

Reinforcement design — Standard reinforcement (N12, N16 bars) is placed vertically and horizontally inside the Dincel panels before the concrete pour. Reinforcement layout is designed to resist bending moments and shear forces from earth pressure, surcharge, and hydrostatic loads. The plastic formwork improves concrete curing by retaining moisture.

Footing design — Dincel walls typically sit on a conventional reinforced concrete strip footing. Footing width and depth depend on wall height, soil bearing capacity, and overturning resistance requirements. Starter bars project from the footing into the Dincel wall panels.

Waterproofing — The PVC plastic skin provides inherent waterproofing. Panel joints are sealed during installation. For below-ground retaining applications, this eliminates the need for separate waterproofing membranes — a significant cost and time saving compared to conventional concrete retaining walls.

Drainage — Despite being waterproof, proper drainage behind the wall is still essential to reduce hydrostatic pressure on the structure. Agricultural drain at the base with free-draining gravel backfill is standard. The waterproof skin means any water that does reach the wall face cannot penetrate — it drains down to the ag-drain.

When Is Engineering Required?

All Dincel retaining walls require engineering. The system is a structural reinforced concrete wall — reinforcement layout, concrete specification, footing design, and connection details must be designed by a structural engineer. This is not a DIY product for retaining applications.

What You Receive

Our engineering package includes structural calculations to AS 4678, construction drawings showing Dincel profile selection, reinforcement layout (vertical and horizontal bars), footing design, drainage details, concrete specification, and an engineer's certificate for council.

Best Applications

Below-ground retaining — basement walls, subfloor retaining where waterproofing is critical.

Boundary walls — the thin profile (200mm) maximises usable space compared to conventional concrete or block walls.

Speed-critical projects — formwork installs at 25m²/hour with two people, no stripping required.

Rendered or clad finish — the PVC surface accepts render, paint, cladding, or gyprock for finished appearances.

Pricing

Dincel retaining wall engineering starts from $800+GST as the reinforcement design is more involved than gravity or post-and-sleeper systems. Complex or tall walls are quoted individually.