Formwork gives concrete its shape. Once the concrete cures and gains sufficient strength, the formwork is removed (stripped).
Types
- Timber formwork: Traditional, flexible, good for custom shapes
- Steel formwork: Reusable 50+ times, smooth finish
- Aluminum formwork: Lightweight, fast assembly
- Plastic formwork: Lightweight, modular systems
Cost Factor
Formwork can represent 35–60% of total concrete structure cost. Efficient formwork design significantly reduces project expenses.
Stripping Time
Columns/walls: 24–48 hours. Slabs (props remain): 3–7 days. Beams: 7–14 days.
Reusable Formwork Systems
On large commercial projects, modular steel or aluminum formwork systems can be reused 50–100+ times before replacement, dramatically lowering the per-pour cost compared to build-once timber forms — this is a major reason large developers standardize on engineered formwork systems rather than custom carpentry for every pour.
Formwork Pressure
Wet concrete behaves like a heavy liquid and exerts significant lateral pressure on formwork — pressure increases with pour height and pour rate, which is why tall wall pours are often done in stages (lifts) rather than all at once, to keep formwork from bursting or bulging under the load.