How to choose concrete formwork: timber or metal

For a single pour or an unusual shape, timber or plywood formwork cut to size is the better choice. For repeated pours, with the same shapes on every cycle, modular metal systems are more suitable. In both cases you need the accessories that keep everything closed and fixed in place: clamps, tensioners, spacers, gaskets and profiles. This collection brings together panels, beams, arch forms, clamps and accessories from several brands.

The types

• Plywood panels: multi-layer formwork panels, such as the KAUFMANN K1 3-ply panel or the 3-S C/T Utility panel. They come with raw or film-faced finishes.
• Formwork beams and panels: load-bearing elements such as the KAUFMANN HT 20plus beam, on which the panels rest.
• Clamps: foundation or strong type, they hold panels and boards together.
• Arch forms: standard and maxi mini-arch forms, elements, supports and tie rods for modular universal arch forms, generally used to make slabs and curved shapes.
• Spacers and spacer cutters: linear spacers to maintain the thickness; spacer cutters (eco and super) are the tools for cutting the spacers.
• Gaskets, waterstops and profiles: formwork gaskets prevent grout leaks; the PVC waterstop seals construction joints; double-chamfer profiles create chamfered edges.

How to choose by job

The features to look at

• Material: spruce and timber for boards and panels, steel and galvanised steel for connecting elements, PVC and HDPE for spacers, gaskets and profiles.
• Finish: raw, film-faced, galvanised or painted. Film-faced leaves a smoother surface on the concrete, while raw has no coating and wears out sooner.
• Weight: in the collection it ranges from 0.5 kg for an accessory up to 43.5 kg for the largest elements. It matters for transport and manual handling.
• Opening and developed length: for arch forms, the opening (for example 430-610 mm or up to 1530-2940 mm) and the developed length (1850, 2900, 3300 mm) tell you the span you can cover.
• Type: modular, universal, linear. Always check that the elements belong to the same system.
• Colour and marking: the data also include grey, blue or bright yellow products; the colour lets you recognise the type of accessory at a glance and find it again in the site store.
• Origin: some items are listed as Italian-made and distributed, a useful detail if the specification requires it.

Common mistakes

• Striking too early: the formwork is removed only when the concrete has reached the required strength.
• Unsealed joints: grout leaks out and the pour is left with honeycombing and uneven edges.
• Insufficient propping: the pressure of the pour deforms the panels.
• Forgetting the release agent: panels and boards stick to the concrete.
• Mixing different systems: beams, clamps and accessories should be bought together, from the same system.

Frequently asked questions

Is timber or metal better?

Timber costs less and adapts to unusual shapes; metal can be reused many more times and is quicker to assemble.

What is the waterstop for?

It is a PVC strip placed in the joint between two pours to stop water passing through.

How should the panels be stored?

Clean after striking, stacked under cover and protected from damp.

What is the difference between a raw and a film-faced panel?

The film-faced panel has a surface coating that gives smoother concrete and can be reused more often. The raw panel is used where the finish matters less or for single pours.

How do I choose the number of clamps and spacers?

It depends on the height of the pour and the wall thickness: the taller the pour, the greater the pressure and the more fixings are needed. It is best to get the quantities from the system manufacturer or the designer.

The full range is in the Formwork and Concrete Pouring Systems collection; for advice on materials or for a quotation, contact the AMES technicians.