Concrete Formwork Options: What Actually Drives the Cost
Every self-builder who starts pricing a concrete wall or foundation eventually types some version of "formwork cost comparison" into a search bar, expecting a clean table: timber at so many euros per square metre, steel at so many, insulated forms at so many. That table does not exist, at least not one built on independent data. What does exist is a set of mechanical, checkable differences between formwork types that change the final bill far more than any single headline percentage. This piece walks through those differences, flags where the only available cost claims come from companies selling the product they are describing, and ends with a short list of questions worth bringing to a quote meeting instead of a price you cannot verify.
Key Takeaways
- There is no independent price table for formwork types; the comparisons online come from companies selling one of them. The cost drivers, though, are mechanical and checkable.
- Six families exist — timber, heavy-duty engineered panels, light plastic modules, stay-in-place tubes, fabric forms and insulated blocks (ICF) — and a self-build usually meets only two.
- The real bill hides in reuse, labour versus equipment, logistics, insulation added later or built in, and waste — five questions that turn any quote into something you can check.
- The oldest ICF cost claim dates from 1959 and was promotional; today's percentage claims have the same origin. Ask where a number comes from before budgeting on it.
- Stripping, propping while the concrete cures, release agent, ties and finish repair are the parts of a formwork job that rarely appear on the first quote.
Why 'concrete formwork cost comparison' searches don't lead to real prices
Formwork exists to hold liquid concrete securely in place while it chemically hardens into its finished shape. That single job can be done with timber boards, steel panels, plastic modules, or permanent insulated blocks, and each route has a genuinely different cost structure on site.
The trouble is what happens when you try to compare them in euros. The detailed comparisons available online are published almost entirely by manufacturers of insulated concrete forms, and the one concrete percentage figure in circulation traces back decades, not to a recent, dated, independently measured study. Belgium-specific pricing, in particular, does not appear in any checkable source. Rather than repeat a number that cannot be defended, this article sets out the cost drivers themselves, so a reader can apply them to their own site and their own quotes.
What formwork actually is, and the six types on offer
Formwork splits into six broad families, and most self-builders only ever hear about two of them.
- Timber formwork is the oldest and simplest type: easy to produce on site and completely flexible in shape, but time-consuming to assemble for anything larger than a small foundation or garden wall. It can also leave a highly irregular surface finish, something that needs planning and extra time if you actually want to use it deliberately, for example as an exposed board-marked concrete look.
- Heavy-duty engineered formwork uses prefabricated panels mounted on a steel or aluminium frame. It assembles quickly in modular sections and can lower overall costs on large projects, but it comes with capital outlay, precision requirements, and the logistics of getting cranes, trucks and shoring to a site.
- Light-duty reusable plastic formwork is modular, lightweight, sometimes made from recycled plastic, and suits repetitive work such as a row of identical mass-housing units.
- Stay-in-place structural formwork is prefabricated fibre-reinforced plastic tubing, mainly for columns and piers, that stays in place after the pour as reinforcement and protection rather than being stripped off.
- Flexible, fabric formwork allows a single pour of an optimised foundation or wall shape and suits situations with seismic loads or high hydrostatic pressure, such as basements, though it is hard to insulate afterward.
- Permanent insulated formwork (ICF) is rigid insulation, usually expanded polystyrene, dry-stacked into interlocking units resembling oversized building blocks, then filled by pumping or pouring concrete inside. The insulation stays in place permanently as the interior and exterior substrate of the wall.
| Type | Reused how often | Labour or equipment heavy | What it suits on a self-build |
|---|---|---|---|
| Timber boards and plywood | A few uses, then discarded | Labour | Foundations, garden walls, awkward one-off shapes |
| Heavy-duty engineered panels | Hundreds to thousands of uses | Equipment, cranes and logistics | Large or repetitive walls; usually hired, not bought |
| Light plastic modules | Many uses, light enough to carry | Labour, but little of it | Repetitive small pours |
| Stay-in-place tubes | Once; it stays in the structure | Neither | Columns and piers |
| Fabric forms | Once | Labour | Basements, high water pressure, odd foundation shapes |
| Insulated blocks (ICF) | Once; it is the wall's insulation | Labour, but unskilled | Whole walls where insulation is wanted anyway |
Why a 1959 'cost-cutting' claim still circulates today
ICF has a surprisingly direct Belgian connection. Durisol, generally regarded as the first insulated concrete form, was developed in Belgium in 1937 by two Swiss nationals, Schnell and Bosshard, building on a Dutch patent from 1932. The following year they founded Durisol AG in Dietikon, Switzerland, and after the Second World War the system spread into the Netherlands, France and Belgium to meet demand for fast, cost-effective construction that did not require highly skilled labour.
By 1959, Durisol was being promoted, according to Barron's reporting from that period, as cutting traditional construction costs by 20 to 30 percent, and was by then produced in thirteen countries. That figure was a promotional claim made by the people selling the product, not a measured, independent comparison against a specific alternative method.
The same shape of claim resurfaces in current ICF marketing. One manufacturer's own comparison page states that ICF's initial material costs can run higher than timber framing, that timber can be more cost-effective at the outset, especially when built with local materials, and that any long-term savings from ICF need to be weighed against that higher starting price. The same source also states that ICF's modular design can reduce the number of trades needed on site and speed up completion, while noting timber frame is also fast to assemble, particularly when prefabricated, with actual speed depending on design complexity and crew experience. It further presents ICF as offering superior thermal, fire, pest, moisture and acoustic performance, describing timber as something that "may require" extra measures to match it. These are reasonable points to raise with a supplier, but they come from a company selling ICF systems, and none of them is attached to an independent, dated study. Treat any percentage figure you encounter the same way you would treat the 1959 claim: ask where the number comes from before you build a budget around it.
A checklist to bring to your formwork quote meeting
Instead of asking a supplier for a price per square metre and accepting it at face value, five questions pull out the real cost drivers behind any formwork quote.
- How many times can the facing be reused? Timber and plywood facings typically need replacing after a handful of uses. Steel, aluminium or phenolic-faced panels can reach several thousand uses depending on how carefully they are cleaned and stored. On a one-off self-build this matters less; on a project with repeated identical pours, it changes the economics completely.
- Is secondary insulation already included, or will it be added afterward? For timber and for heavy-duty engineered formwork used in a dwelling, insulation is usually a separate step added later, with its own time and cost. With ICF, the insulation is the form itself, so that line item effectively moves earlier in the budget rather than disappearing.
- Does your labour cost or your equipment cost dominate? Timber formwork tends to make sense where labour is cheaper than procuring and setting up reusable formwork, or for awkward, one-off sections a standard system cannot handle. Heavy-duty engineered systems shift the balance the other way, trading labour hours for capital spent on panels and cranes.
- What does getting the system to site actually require? Heavy-duty engineered formwork brings genuine logistics costs: cranes, trucks and shoring, plus the precision needed to assemble panels correctly. A quote that excludes delivery, lifting and site access should be treated as incomplete.
- Who pays for the waste? Plywood and timber formwork is often used once and then discarded, which adds both a disposal cost and a material cost that does not show up until the skip arrives. Ask whether your quote already accounts for it.
The parts of the job the first quote leaves out
Whatever the system, a formwork job has a second half that beginners forget to price, because it happens after the pour and does not show up as a material.
Striking and propping. The forms have to come off, and the concrete has to be able to stand without them. A wall can usually be stripped within a day or two; a suspended slab stays on its props for weeks while the concrete gains strength, and those props are hired by the week. A quote that prices the formwork but not the propping period is quoting half the job.
Ties and tie holes. Panel systems hold the two faces together with through-ties under the pressure of wet concrete. Every tie leaves a hole that has to be plugged, and on a wall that will stay visible, plugged neatly. Timber formwork uses its own ties and walers; ICF has the ties built into the block.
Release agent and cleaning. Reusable faces get a release agent before each pour and a clean after it, or the next pour sticks and tears the face. That is a labour line nobody writes down and everybody pays.
Finish repair. Board-marked timber gives a rough face; a panel system gives a smooth one with tie holes; ICF gives no concrete face at all, only insulation to be rendered or clad. If the wall is to be seen, the cost of making the finish presentable belongs in the comparison, and it differs by system more than the formwork itself does.
The pour it has to survive. Wet concrete pushes hard at the bottom of a tall form. Pouring in lifts, vibrating carefully and bracing properly are not optional with any system, and a blow-out — a form that bursts mid-pour — costs more in wasted concrete and lost time than any saving on the forms. Ask who is responsible for bracing design, especially on ICF, where a tall wall filled in one go is the classic beginner's mistake.
What is EPS foam, and is it the same as Styrofoam?
Most modern ICF systems use expanded polystyrene, usually shortened to EPS, which is made up of roughly 2 percent polystyrene and 98 percent air. It is often called Styrofoam in everyday conversation, but that is technically incorrect: Styrofoam is a specific, differently manufactured extruded foam product. The confusion is common enough that it is worth clarifying before a supplier's sales sheet uses the terms interchangeably.
Frequently asked questions
Is timber formwork the cheapest option for a self-build? For a one-off foundation or a short wall, usually: the boards are cheap, the shapes are flexible and no equipment needs hiring. The saving disappears as soon as the job is large or repetitive, because the labour of building forms by hand grows with every metre and the boards are thrown away.
Should I buy or hire panel formwork? Hire. Engineered panels pay for themselves over thousands of uses; a self-build needs them for a few weeks. Price the hire period, the delivery, the crane and the cleaning charge on return.
Does ICF really save money? It moves money rather than removing it. The insulation that a timber or panel wall needs later is already in the block, so the formwork line is higher and the insulation line is lower. Whether the total is lower depends on your site, your labour and what you would have paid for insulation anyway — not on a brochure's percentage.
What is the most common mistake? Pricing the forms and forgetting the propping period, the finish and the bracing. The second half of the job is where the surprise invoices live.
Conclusion
None of this replaces the quote you will eventually get from a contractor, and it should not. What it offers instead is a way to read that quote critically: which cost driver is pushing the number up, and whether the comparison being offered to you is grounded in your own site conditions or borrowed from a vendor's brochure. The gap between a 1937 Belgian invention and a 2026 ICF sales page is wide, but the habit of quoting an unverified percentage has stayed remarkably constant across that stretch of time.