Curved Formwork: Shaping Modern Concrete Design

Why curves are harder to form

Curved walls, kerbs, planter boxes and feature edges are popular in Australian homes and commercial projects, but they're harder to form than straight runs. The facing has to follow the radius smoothly, the supports have to hold it there under concrete pressure, and the joints have to stay tight so slurry doesn't leak.

Common ways to form a curve

• Kerfed or thin plywood. Cheap and familiar, but it often cracks at tight radii and swells after a few wet pours.

• Steel or purpose-made curved panels. Accurate and durable, but expensive and heavy. They suit repetitive civil work better than one-off jobs.

• Plastic formwork sheets. Waterproof sheets that can be cut to suit and reused 50–100+ times. How tightly a sheet will bend depends on its thickness, so confirm the radius with us before you plan around it. For tight curves, facing fixed to a profiled frame is often the better option.

Setting out and building curved formwork

1. Mark the curve with a string line from a fixed centre point, or set it out from the drawings.

2. Build the supporting frame (studs, walers or profiled ribs) to the radius first. Curves usually need closer support spacing than straight walls, so follow the formwork design.

3. Fix the facing to the frame, working from one end so it beds evenly against each support.

4. Seal or tape the joints, then check the radius and plumb at several points before the pour.

5. Pour in even lifts and vibrate carefully so the curve doesn't push out.

Common mistakes

• Forcing the facing past the radius it can take, which leads to cracking or flat spots.

• Spacing supports too far apart, so the face bulges between them.

• Reusing swollen or delaminated plywood, which leaves a wavy finish.

• Skipping a design check. In Australia, AS 3610 and Safe Work Australia's formwork guidance are the key references. Have curved formwork designed and inspected by a competent person.

Why plastic sheets suit repeat curves

If you form the same curve more than once, such as matching planters or a run of curved kerbs, reusable plastic sheets keep their shape because they're waterproof and don't swell. Their smooth face also reduces patching on exposed concrete. Over 50–100+ uses, that can mean a saving of up to 70–80% on replacement costs compared with plywood.

Planning a curved pour? Get a Quote and send us your drawings.