How to choose metal-frame formwork: panels and accessories

Metal-frame formwork is the right choice when you need to pour concrete walls and columns and reuse the same panels several times, as on sites with repeated pours. The panels have a steel or aluminium frame and are joined with clamps; to keep the two faces at the right distance you need ties and spacers, and to hold them upright you need props. The system only works if the components are compatible with each other: the panels alone are not enough.

The types

• Complete frame systems: modular panels with a metal frame, such as Panawall and Panawall Plus or the Panalex frame formwork. They are placed side by side to give the length and height of the pour.
• Clamps: hold the panels together along the edges. There are several types and they must be chosen to suit the system.
• Wedges: steel wedges (black, painted or larger format) that lock the form ties or the connections. They are used with a hammer.
• Form ties and tie rods: form ties (including loop ties) and tensioners connect the two faces of the wall and withstand the pressure of the fresh concrete.
• Spacers and joints: in plastic, PVC or fibre cement, they maintain the wall thickness; you will find them in sets such as the Mafi plastic spacers and joint.
• Propping systems: elements to keep the panels stable and plumb, such as the Panalex propping systems.

How to choose by job

The features to look at

• Material: galvanised or painted steel for panels, wedges and clamps; plastic, PVC or asbestos-free fibre cement for the spacers; drawn steel with rounded edges for some connecting components. Galvanised steel stands up better to site damp.
• Finish: galvanised, painted or black. Galvanising lasts a long time outdoors, while paint needs touching up when it gets scratched.
• Compatibility: clamps, wedges and tie rods are designed for one specific system. When you order spares, state the system (for example Panawall) and not just the size.
• Quantity: many components (wedges, spacers, clamps) are needed in large numbers for each pour. Work out how many you use per metre of wall before ordering.

Common mistakes

• Mixing components from different systems: clamps and wedges that do not fit together leave gaps and grout leaks.
• Forgetting the release agent: without the product on the face of the panels the concrete sticks and the panels get damaged.
• Too few ties: the pressure of fresh concrete is high, especially on tall pours. The number should be decided with the engineer.
• Not checking plumb: if the panels are not vertical the wall comes out crooked and it cannot be corrected afterwards.
• Storing dirty panels: after striking they must be cleaned, otherwise hardened concrete builds up and reuse gets worse.

Frequently asked questions

How many times can frame formwork be reused?

Many times, if it is cleaned after every striking and treated with release agent. The exact number depends on the system and on how it is used.

What does it mean when the spacer stays in the pour?

Generally the PVC or fibre cement tubes remain in the concrete and the tie rod passes through them. How to close the ends depends on the system: ask our technicians.

Can I buy just the clamps or the wedges?

Yes, as spares, as long as they belong to the system you use. State the name of the system when you ask for a quotation.

How do I calculate how many panels I need?

Start from the length and height of the wall or the dimensions of the column and divide by the panel size of the system. Add the corner and filler elements, if the system provides them. An AMES technician can work it out with you from the drawing.

Do I need a technician for assembly?

Assembly is simple, but the propping and the number of ties depend on the height and pressure of the pour. For tall pours it is best to have them checked by the works supervisor or the designer.

You will find the systems and accessories in the Steel-Frame Formwork collection; to choose the right components or request a quotation, ask the AMES technicians.