What is falsework (cimbra) and why we are named after it
Andrés Segnini Capriles6 min read
Falsework (in Spanish, cimbra) is the temporary frame that holds up an arch, or any other structure, while it is being built. It works while the structure can’t support itself and is removed as soon as it can. It is one of the oldest pieces in construction, and it is also the idea our name comes from.
The definition
The Royal Spanish Academy’s dictionary defines cimbra, in its construction sense, as the frame that holds up an arch or other structure during its construction. The verb that closes its cycle is descimbrar, what English builders call striking the centering: removing it once an arch or vault has been built.
The word has a second meaning in architecture, the curvature of the inner face of an arch or vault, hence expressions such as arco de plena cimbra, an arch that forms a full semicircle.
Why an arch needs it
A voussoir arch (made of the wedge-shaped pieces called voussoirs) can’t carry any load until it is complete. Each voussoir rests on the previous one and pushes on the next, but that balance only exists once the last one, the keystone, is set at the top. Until then, something has to carry the weight. That something is the centering.
- 1. The centering goes upA rib shaped like the arch, on props standing on the ground.
- 2. The voussoirs are laidFrom the springing upward, each one resting on the centering.
- 3. The keystone is setThe last piece locks everything in place: the arch now works on its own.
- 4. The centering is struckThe centering is removed and the arch stands on its own.
Falsework today
The principle is the same, but its use now goes far beyond the arch. In today’s construction, falsework is mainly the temporary structure that supports the formwork and the fresh concrete until the element is strong enough to carry itself: floor slabs, beams or bridge decks.
Technical prevention note NTP 1069 from Spain’s National Institute for Safety and Health at Work (INSST) groups falsework by the load it carries:
| Type | Load per standard | Typical use |
|---|---|---|
| Light-duty falsework | Under 25 kN | Building work, where a single prop isn’t enough |
| Medium-duty falsework | Between 30 and 80 kN | Frame systems, multidirectional systems or braced props |
| Heavy-duty falsework | Up to 1,200 kN | Civil engineering: viaducts and major shoring |
Source: INSST, NTP 1069, Cimbras montadas con elementos prefabricados (I): normas constructivas (2016).
Its design is governed by the standard EN 12812:2008, “Falsework. Performance requirements and general design”, which distinguishes two classes: class A, for standard, well-proven setups within certain limits (for example, beam and slab spans of no more than 6 meters), and class B, which requires specific structural calculation. In both cases, erecting or dismantling without following the technical instructions is one of the causes of collapse that the NTP points out.
Falsework, formwork and props are not the same thing
- Formwork is the mold: it shapes the concrete while it sets.
- Falsework is the structure that holds that mold, and the weight of the concrete, at the right height.
- A prop is a single vertical element; when the load or the height exceeds it, falsework is needed.
Falsework isn’t the building. It is what allows the building to stand on its own.
Why we are called Cimbrium
Because a construction project has the same problem as a half-built arch: for months, nothing stands on its own. The client has committed money that doesn’t yet have work behind it; the contractor has done work that hasn’t yet been paid; the company’s numbers can’t be seen until the books close. Trust between the parties is like an arch without its keystone: it isn’t carrying anything yet.
Cimbrium aims to be that temporary structure for the money in a project: holding up the budget, the capital, the verification and the taxes while the work progresses, and stepping away once trust no longer needs scaffolding.
| Division | What it holds up |
|---|---|
| CostPact | The budget on real prices and project management: progress certificates, cost control, purchasing and subcontractors. Live. |
| PactStream | The capital for each milestone in a regulated escrow account, released against verified progress. Built and switching on with our first clients, with custody through a regulated payment provider. |
| FiscalCore | The taxes on each payment: drafts of Spain’s tax forms 303, 111 and 130 and the split into taxes, costs and profit. Live. |
| PropertyJourney | When the project is a real estate development, the sales that start it and the handover and after-sales that close it. |
Frequently asked questions
What is falsework in construction?
It is the temporary frame that holds up an arch or other structure while it is being built. Today it is mainly used to support the formwork and fresh concrete of floor slabs, beams and bridge decks until the element can carry itself.
What does striking the centering mean?
Removing the centering once an arch or vault has been built; in Spanish, descimbrar, as defined by the Royal Spanish Academy. In concrete work, it means removing the temporary structure once the element is strong enough to carry itself.
What is the difference between falsework and formwork?
Formwork is the mold that shapes the concrete. Falsework is the structure that holds that mold, and the weight of the concrete, at the right height while it sets.
Which standard governs falsework?
EN 12812:2008, “Falsework. Performance requirements and general design” (UNE-EN 12812 in Spain), which distinguishes a class A for standard setups within certain limits and a class B that requires specific structural calculation.
Sources: RAE, cimbra and descimbrar · INSST, NTP 1069 · UNE-EN 12812:2008.
